* ftrace function-graph and interprocessor interrupts
@ 2014-09-24 21:14 Elliott, Robert (Server Storage)
2014-09-24 21:49 ` Andi Kleen
0 siblings, 1 reply; 6+ messages in thread
From: Elliott, Robert (Server Storage) @ 2014-09-24 21:14 UTC (permalink / raw)
To: Steven Rostedt, linux-kernel
Cc: Jens Axboe <axboe@kernel.dk> (axboe@kernel.dk), Christoph Hellwig
The function-graph tracer marks some interrupt handler functions
with ==========> and <========== labels.
10) | sd_setup_read_write_cmnd [sd_mod]() {
10) | scsi_init_io() {
10) | scsi_init_sgtable() {
10) | scsi_alloc_sgtable() {
10) ==========> |
10) | smp_apic_timer_interrupt() {
10) | irq_enter() {
10) 0.093 us | rcu_irq_enter();
10) 0.102 us | irqtime_account_irq();
10) 1.213 us | } /* irq_enter */
...
10) 0.054 us | idle_cpu();
10) 0.077 us | rcu_irq_exit();
10) 6.953 us | } /* irq_exit */
10) + 45.238 us | } /* smp_apic_timer_interrupt */
10) <========== |
10) + 46.256 us | } /* scsi_alloc_sgtable */
10) | blk_rq_map_sg() {
10) 0.101 us | __blk_bios_map_sg();
Interprocessor interrupts are not marked, though (on x86_64). In
this example, smp_call_function_single_interrupt is really in hardirq
context. The trace just shows it at the same level as the function
it interrupted.
10) 0.068 us | scsi_prep_state_check();
10) 0.095 us | get_device();
10) | scsi_mq_prep_fn() {
10) 0.063 us | init_timer_key();
10) | scsi_setup_cmnd() {
10) | sd_init_command [sd_mod]() {
10) | sd_setup_read_write_cmnd [sd_mod]() {
10) | smp_call_function_single_interrupt() {
10) | irq_enter() {
10) 0.096 us | rcu_irq_enter();
10) 0.116 us | irqtime_account_irq();
10) 1.243 us | } /* irq_enter */
10) | generic_smp_call_function_single_interrupt() {
10) | flush_smp_call_function_queue() {
10) | __blk_mq_complete_request_remote() {
10) | scsi_softirq_done() {
10) | scsi_decide_disposition() {
...
10) + 36.788 us | } /* smp_call_function_single_interrupt */
10) | scsi_init_io() {
10) | scsi_init_sgtable() {
10) 0.098 us | scsi_alloc_sgtable();
10) | blk_rq_map_sg() {
10) 0.148 us | __blk_bios_map_sg();
10) 0.722 us | } /* blk_rq_map_sg */
10) 1.862 us | } /* scsi_init_sgtable */
10) 2.424 us | } /* scsi_init_io */
10) 3.080 us | } /* sd_setup_read_write_cmnd [sd_mod] */
10) + 41.431 us | } /* sd_init_command [sd_mod] */
10) + 42.012 us | } /* scsi_setup_cmnd */
10) + 43.179 us | } /* scsi_mq_prep_fn */
The plain function tracer shows that smp_call_function_single_interrupt
is really in hardirq context, marking it with "h":
fio-4607 [010] .... 5908.340807: blkdev_get_block <-do_direct_IO
fio-4607 [010] .... 5908.340807: put_page <-do_direct_IO
fio-4607 [010] d.h. 5908.340808: generic_smp_call_function_single_interrupt <-smp_call_function_single_interrupt
fio-4607 [010] d.h. 5908.340808: flush_smp_call_function_queue <-generic_smp_call_function_single_interrupt
fio-4607 [010] d.h. 5908.340808: __blk_mq_complete_request_remote <-flush_smp_call_function_queue
fio-4607 [010] d.h. 5908.340808: scsi_softirq_done <-__blk_mq_complete_request_remote
fio-4607 [010] d.h. 5908.340808: scsi_decide_disposition <-scsi_softirq_done
fio-4607 [010] d.h. 5908.340808: scsi_handle_queue_ramp_up <-scsi_decide_disposition
blk-mq (and scsi-mq) can generate lots of IPIs if
/sys/block/sdNN/device/rq_affinity is 1 or 2 (which force block layer
completion processing to be done on the submitting CPU node or
submitting CPU).
This code in check_irq_entry() apparently doesn't detect IPIs:
if ((addr < (unsigned long)__irqentry_text_start) ||
(addr >= (unsigned long)__irqentry_text_end))
return 0;
In scsi-mq tests, do_IRQ and smp_apic_timer_interrupt are the only
ones that show up.
The __irq_entry attribute apparently tells the linker to place
the functions in that range:
./arch/x86/kernel/irq.c:__visible unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
./arch/x86/kernel/apic/apic.c:__visible void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs)
./arch/x86/kernel/apic/apic.c:__visible void __irq_entry smp_trace_apic_timer_interrupt(struct pt_regs *regs)
but adding that attribute to these functions in irq.c does not help:
./arch/x86/kernel/irq.c:__visible void __irq_entry smp_x86_platform_ipi(struct pt_regs *regs)
./arch/x86/kernel/irq.c:__visible void __irq_entry smp_trace_x86_platform_ipi(struct pt_regs *regs)
Unlike do_IRQ and smp_apic_timer_interrupt, those function names never
appear in the function-graph; the first function I see is always
generic_smp_call_function_single_interrupt.
blk-mq calls smp_call_function_single_async directly, which
can result in generic_smp_call_function_single_interrupt on the
local CPU, and that call chain shouldn't be treated as being in
a new interrupt context. When this happens, it is already in a
interupt context call chain from do_IRQ.
---
Rob Elliott HP Server Storage
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: ftrace function-graph and interprocessor interrupts
2014-09-24 21:14 ftrace function-graph and interprocessor interrupts Elliott, Robert (Server Storage)
@ 2014-09-24 21:49 ` Andi Kleen
2014-09-24 22:02 ` Elliott, Robert (Server Storage)
2014-09-25 20:38 ` Steven Rostedt
0 siblings, 2 replies; 6+ messages in thread
From: Andi Kleen @ 2014-09-24 21:49 UTC (permalink / raw)
To: Elliott, Robert (Server Storage)
Cc: Steven Rostedt, linux-kernel,
Jens Axboe <axboe@kernel.dk> (axboe@kernel.dk),
Christoph Hellwig
"Elliott, Robert (Server Storage)" <Elliott@hp.com> writes:
> The function-graph tracer marks some interrupt handler functions
> with ==========> and <========== labels.
I'm not sure the marking is really that useful. Isn't it always obvious
from the function names where an interrupt starts/end?
-Andi
--
ak@linux.intel.com -- Speaking for myself only
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: ftrace function-graph and interprocessor interrupts
2014-09-24 21:49 ` Andi Kleen
@ 2014-09-24 22:02 ` Elliott, Robert (Server Storage)
2014-09-25 20:38 ` Steven Rostedt
1 sibling, 0 replies; 6+ messages in thread
From: Elliott, Robert (Server Storage) @ 2014-09-24 22:02 UTC (permalink / raw)
To: Andi Kleen
Cc: Steven Rostedt, linux-kernel,
Jens Axboe <axboe@kernel.dk> (axboe@kernel.dk),
Christoph Hellwig
> -----Original Message-----
> From: Andi Kleen [mailto:andi@firstfloor.org]
> Sent: Wednesday, 24 September, 2014 4:50 PM
> To: Elliott, Robert (Server Storage)
> Cc: Steven Rostedt; linux-kernel@vger.kernel.org; Jens Axboe
> <axboe@kernel.dk> (axboe@kernel.dk); Christoph Hellwig
> Subject: Re: ftrace function-graph and interprocessor interrupts
>
> "Elliott, Robert (Server Storage)" <Elliott@hp.com> writes:
>
> > The function-graph tracer marks some interrupt handler functions
> > with ==========> and <========== labels.
>
> I'm not sure the marking is really that useful. Isn't it always obvious
> from the function names where an interrupt starts/end?
>
> -Andi
Although the do_IRQ name stands out pretty well, some of the
others don't, and blk-mq calling them directly makes it hard
to tell. They show up clearly in the function trace, just
not the function_graph trace.
Also, the IPI function can end up nested inside { } but
without indents, depending on when it occurs.
10) | sd_setup_read_write_cmnd [sd_mod]() {
10) | smp_call_function_single_interrupt() {
10) | irq_enter() {
...
10) + 36.788 us | } /* smp_call_function_single_interrupt */
10) | scsi_init_io() {
The ==> labels also add an indent level.
I'd like to add an option to exclude the time taken by interrupts
in the cumulative times, but that first requires that function_graph
understand what times to exclude.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: ftrace function-graph and interprocessor interrupts
2014-09-24 21:49 ` Andi Kleen
2014-09-24 22:02 ` Elliott, Robert (Server Storage)
@ 2014-09-25 20:38 ` Steven Rostedt
2014-09-25 23:10 ` Elliott, Robert (Server Storage)
1 sibling, 1 reply; 6+ messages in thread
From: Steven Rostedt @ 2014-09-25 20:38 UTC (permalink / raw)
To: Andi Kleen
Cc: Elliott, Robert (Server Storage),
linux-kernel,
Jens Axboe <axboe@kernel.dk> (axboe@kernel.dk),
Christoph Hellwig, Frederic Weisbecker
On Wed, 24 Sep 2014 14:49:41 -0700
Andi Kleen <andi@firstfloor.org> wrote:
> "Elliott, Robert (Server Storage)" <Elliott@hp.com> writes:
>
> > The function-graph tracer marks some interrupt handler functions
> > with ==========> and <========== labels.
>
> I'm not sure the marking is really that useful. Isn't it always obvious
> from the function names where an interrupt starts/end?
>
Note, I find the markings useful, if anything, it makes it easier to
see when the system was interrupted. Not to mention, if it's broken, we
need to fix it.
Does, this patch fix it for you?
-- Steve
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 488273458bfd..bb48ec08edf8 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -50,6 +50,7 @@ struct fgraph_cpu_data {
int depth;
int depth_irq;
int ignore;
+ int in_irq;
unsigned long enter_funcs[FTRACE_RETFUNC_DEPTH];
};
@@ -693,16 +694,64 @@ static int print_graph_abs_time(u64 t, struct trace_seq *s)
(unsigned long)t, usecs_rem);
}
+enum {
+ FGRAPH_IRQ_ADDR = 1,
+ FGRAPH_IRQ_FLAG = 2,
+};
+
+static int fgraph_in_irq(struct trace_entry *ent, unsigned long addr)
+{
+ if ((addr >= (unsigned long)__irqentry_text_start) &&
+ (addr < (unsigned long)__irqentry_text_end))
+ return FGRAPH_IRQ_ADDR;
+
+ if (ent->flags & TRACE_FLAG_HARDIRQ)
+ return FGRAPH_IRQ_FLAG;
+
+ return 0;
+}
+
static enum print_line_t
-print_graph_irq(struct trace_iterator *iter, unsigned long addr,
- enum trace_type type, int cpu, pid_t pid, u32 flags)
+print_graph_irq(struct trace_iterator *iter, struct trace_entry *ent,
+ unsigned long addr, enum trace_type type, int cpu,
+ pid_t pid, u32 flags)
{
- int ret;
+ unsigned int irq_flags = ent->flags;
+ struct fgraph_data *data = iter->private;
struct trace_seq *s = &iter->seq;
+ int *cpu_in_irq;
+ int in_irq;
+ int ret;
- if (addr < (unsigned long)__irqentry_text_start ||
- addr >= (unsigned long)__irqentry_text_end)
- return TRACE_TYPE_UNHANDLED;
+ cpu_in_irq = &(per_cpu_ptr(data->cpu_data, cpu)->in_irq);
+ in_irq = fgraph_in_irq(ent, addr);
+
+ /*
+ * When testing if we are entering or leaving an IRQ
+ * we need to know how we got into this function.
+ * Most irqs are within the irqentry text, but not all
+ * of them. Those that we detect with the irqentry text
+ * we stay in the irq until we hit the return address
+ * from the irqentry text.
+ * If we flagged being in an interrupt from the hard
+ * irq flags, that means the interrupt handler was not
+ * within the irqentry text, and we stay in the interrupt
+ * until that flag is cleared.
+ */
+ switch (*cpu_in_irq) {
+ case 0:
+ if (!in_irq)
+ return TRACE_TYPE_UNHANDLED;
+ break;
+ case FGRAPH_IRQ_ADDR:
+ if (in_irq != FGRAPH_IRQ_ADDR)
+ return TRACE_TYPE_UNHANDLED;
+ break;
+ case FGRAPH_IRQ_FLAG:
+ if (in_irq == FGRAPH_IRQ_FLAG)
+ return TRACE_TYPE_UNHANDLED;
+ break;
+ }
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
/* Absolute time */
@@ -735,10 +784,19 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
if (ret != TRACE_TYPE_HANDLED)
return ret;
- if (type == TRACE_GRAPH_ENT)
- ret = trace_seq_puts(s, "==========>");
- else
+ if (trace_flags & TRACE_ITER_LATENCY_FMT) {
+ ret = print_graph_lat_fmt(s, ent);
+ if (ret == TRACE_TYPE_PARTIAL_LINE)
+ return TRACE_TYPE_PARTIAL_LINE;
+ }
+
+ if (*cpu_in_irq) {
ret = trace_seq_puts(s, "<==========");
+ *cpu_in_irq = 0;
+ } else {
+ ret = trace_seq_puts(s, "==========>");
+ *cpu_in_irq = in_irq;
+ }
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
@@ -968,7 +1026,7 @@ print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
if (type) {
/* Interrupt */
- ret = print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
+ ret = print_graph_irq(iter, ent, addr, type, cpu, ent->pid, flags);
if (ret == TRACE_TYPE_PARTIAL_LINE)
return TRACE_TYPE_PARTIAL_LINE;
}
@@ -1047,8 +1105,7 @@ check_irq_entry(struct trace_iterator *iter, u32 flags,
if (*depth_irq >= 0)
return 1;
- if ((addr < (unsigned long)__irqentry_text_start) ||
- (addr >= (unsigned long)__irqentry_text_end))
+ if (!fgraph_in_irq(iter->ent, addr))
return 0;
/*
@@ -1226,7 +1283,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
return TRACE_TYPE_PARTIAL_LINE;
}
- ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
+ ret = print_graph_irq(iter, ent, trace->func, TRACE_GRAPH_RET,
cpu, pid, flags);
if (ret == TRACE_TYPE_PARTIAL_LINE)
return TRACE_TYPE_PARTIAL_LINE;
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: ftrace function-graph and interprocessor interrupts
2014-09-25 20:38 ` Steven Rostedt
@ 2014-09-25 23:10 ` Elliott, Robert (Server Storage)
2014-09-25 23:38 ` Steven Rostedt
0 siblings, 1 reply; 6+ messages in thread
From: Elliott, Robert (Server Storage) @ 2014-09-25 23:10 UTC (permalink / raw)
To: Steven Rostedt, Andi Kleen
Cc: linux-kernel,
Jens Axboe <axboe@kernel.dk> (axboe@kernel.dk),
Christoph Hellwig, Frederic Weisbecker
> -----Original Message-----
> From: Steven Rostedt [mailto:rostedt@goodmis.org]
...
> Does, this patch fix it for you?
>
> -- Steve
...
> - if (type == TRACE_GRAPH_ENT)
> - ret = trace_seq_puts(s, "==========>");
> - else
> + if (trace_flags & TRACE_ITER_LATENCY_FMT) {
> + ret = print_graph_lat_fmt(s, ent);
> + if (ret == TRACE_TYPE_PARTIAL_LINE)
> + return TRACE_TYPE_PARTIAL_LINE;
> + }
> +
> + if (*cpu_in_irq) {
> ret = trace_seq_puts(s, "<==========");
> + *cpu_in_irq = 0;
> + } else {
> + ret = trace_seq_puts(s, "==========>");
> + *cpu_in_irq = in_irq;
> + }
That changes the direction of the arrows (which is fine, if
intended).
Results:
The beginning and end of do_IRQ are marked, but it drops off
during the middle. The normal function trace shows all of those
still in hardirq context.
10) <========== |
10) | do_IRQ() {
10) | irq_enter() {
10) 0.082 us | rcu_irq_enter();
10) 0.101 us | irqtime_account_irq();
10) 1.321 us | } /* irq_enter */
10) ==========> |
10) 0.058 us | exit_idle();
10) | handle_irq() {
10) 0.091 us | irq_to_desc();
10) | handle_edge_irq() {
10) 0.068 us | _raw_spin_lock();
10) 0.142 us | ir_ack_apic_edge();
10) | handle_irq_event() {
10) | handle_irq_event_percpu() {
...
10) 0.092 us | add_interrupt_randomness();
10) 0.080 us | note_interrupt();
10) 9.510 us | } /* handle_irq_event_percpu */
10) 0.071 us | _raw_spin_lock();
10) + 10.577 us | } /* handle_irq_event */
10) + 12.310 us | } /* handle_edge_irq */
10) + 13.901 us | } /* handle_irq */
10) | irq_exit() {
10) 0.111 us | irqtime_account_irq();
10) <========== |
10) 0.074 us | idle_cpu();
10) 0.080 us | rcu_irq_exit();
10) 1.800 us | } /* irq_exit */
10) + 19.132 us | } /* do_IRQ */
10) ==========> |
Same with smp_apic_timer_interrupt:
10) <========== |
10) | smp_apic_timer_interrupt() {
10) | irq_enter() {
10) 0.072 us | rcu_irq_enter();
10) 0.099 us | irqtime_account_irq();
10) 1.069 us | } /* irq_enter */
10) ==========> |
10) 0.060 us | exit_idle();
10) | local_apic_timer_interrupt() {
10) | hrtimer_interrupt() {
...
10) 1.810 us | } /* tick_program_event */
10) + 32.361 us | } /* hrtimer_interrupt */
10) + 32.904 us | } /* local_apic_timer_interrupt */
10) | irq_exit() {
10) 0.111 us | irqtime_account_irq();
10) <========== |
10) | __do_softirq() {
10) 0.058 us | msecs_to_jiffies();
10) 0.099 us | irqtime_account_irq();
10) | smp_call_function_single_interrupt() {
10) | irq_enter() {
10) 0.069 us | rcu_irq_enter();
10) 0.100 us | irqtime_account_irq();
10) 1.251 us | } /* irq_enter */
10) ==========> |
generic_smp_call_function_single_interrupt doesn't
seem to be getting marked, even though function trace
finds many that are in hardirq context.
fio-7146 [010] d... 2968.183376: smp_call_function_single_interrupt <-call_function_single_interrupt
fio-7146 [010] d... 2968.183376: irq_enter <-smp_call_function_single_interrupt
fio-7146 [010] d... 2968.183377: rcu_irq_enter <-irq_enter
fio-7146 [010] d... 2968.183377: irqtime_account_irq <-irq_enter
fio-7146 [010] d.h. 2968.183377: generic_smp_call_function_single_interrupt <-smp_call_function_single_interrupt
fio-7146 [010] d.h. 2968.183377: flush_smp_call_function_queue <-generic_smp_call_function_single_interrupt
fio-7146 [010] d.h. 2968.183378: __blk_mq_complete_request_remote <-flush_smp_call_function_queue
fio-7146 [010] d.h. 2968.183378: scsi_softirq_done <-__blk_mq_complete_request_remote
fio-7146 [010] d.h. 2968.183378: scsi_decide_disposition <-scsi_softirq_done
Here's a longer excerpt starting with back-to-back arrows.
After that they seem flipped again. This shows a
generic_smp_call_function_single_interrupt call.
10) 0.079 us | rcu_irq_exit();
10) 1.829 us | } /* irq_exit */
10) + 26.462 us | } /* do_IRQ */
10) <========== |
10) ==========> |
10) | do_IRQ() {
10) | irq_enter() {
10) 0.078 us | rcu_irq_enter();
10) 0.108 us | irqtime_account_irq();
10) 1.200 us | } /* irq_enter */
10) 0.053 us | exit_idle();
10) | handle_irq() {
10) 0.104 us | irq_to_desc();
10) | handle_edge_irq() {
10) 0.072 us | _raw_spin_lock();
10) 0.153 us | ir_ack_apic_edge();
10) | handle_irq_event() {
10) | handle_irq_event_percpu() {
10) | do_hpsa_intr_msi [hpsa]() {
10) 0.144 us | SA5_performant_completed [hpsa]();
10) 0.749 us | } /* do_hpsa_intr_msi [hpsa] */
10) 0.082 us | add_interrupt_randomness();
10) 0.075 us | note_interrupt();
10) 2.470 us | } /* handle_irq_event_percpu */
10) 0.062 us | _raw_spin_lock();
10) 3.556 us | } /* handle_irq_event */
10) 5.332 us | } /* handle_edge_irq */
10) 6.521 us | } /* handle_irq */
10) | irq_exit() {
10) 0.108 us | irqtime_account_irq();
10) 0.060 us | idle_cpu();
10) 0.079 us | rcu_irq_exit();
10) 1.752 us | } /* irq_exit */
10) + 11.513 us | } /* do_IRQ */
10) <========== |
10) | scsi_init_io() {
10) | scsi_init_sgtable() {
10) 0.109 us | scsi_alloc_sgtable();
10) | blk_rq_map_sg() {
10) 0.134 us | __blk_bios_map_sg();
10) 0.697 us | } /* blk_rq_map_sg */
10) 1.864 us | } /* scsi_init_sgtable */
10) 2.436 us | } /* scsi_init_io */
10) + 42.767 us | } /* sd_setup_read_write_cmnd [sd_mod] */
10) + 43.329 us | } /* sd_init_command [sd_mod] */
10) + 43.886 us | } /* scsi_setup_cmnd */
10) + 45.100 us | } /* scsi_mq_prep_fn */
10) 0.080 us | scsi_init_cmd_errh();
10) | scsi_dispatch_cmd() {
10) 0.057 us | scsi_log_send();
10) | hpsa_scsi_queue_command [hpsa]() {
10) 0.125 us | cmd_tagged_alloc [hpsa]();
10) | hpsa_ioaccel_submit [hpsa]() {
10) 0.193 us | hpsa_cmd_init [hpsa]();
10) | hpsa_scsi_ioaccel_queue_command [hpsa]() {
10) | hpsa_scsi_ioaccel2_queue_command [hpsa]() {
10) 0.057 us | fixup_ioaccel_cdb [hpsa]();
10) 0.112 us | scsi_dma_map();
10) | enqueue_cmd_and_start_io [hpsa]() {
10) 0.087 us | __enqueue_cmd_and_start_io [hpsa]();
10) 0.701 us | } /* enqueue_cmd_and_start_io [hpsa] */
10) 2.627 us | } /* hpsa_scsi_ioaccel2_queue_command [hpsa] */
10) 3.146 us | } /* hpsa_scsi_ioaccel_queue_command [hpsa] */
10) 4.394 us | } /* hpsa_ioaccel_submit [hpsa] */
10) 5.909 us | } /* hpsa_scsi_queue_command [hpsa] */
10) 7.034 us | } /* scsi_dispatch_cmd */
10) + 54.950 us | } /* scsi_queue_rq */
10) + 60.213 us | } /* __blk_mq_run_hw_queue */
10) + 60.760 us | } /* blk_mq_run_hw_queue */
10) ! 112.938 us | } /* blk_sq_make_request */
10) ! 115.912 us | } /* generic_make_request */
10) ! 116.470 us | } /* submit_bio */
10) | blk_finish_plug() {
10) 0.063 us | blk_flush_plug_list();
10) 0.695 us | } /* blk_finish_plug */
10) 0.104 us | _raw_spin_lock_irqsave();
10) 0.086 us | _raw_spin_unlock_irqrestore();
10) ! 179.456 us | } /* __blockdev_direct_IO */
10) ! 180.009 us | } /* blkdev_direct_IO */
10) ! 181.178 us | } /* generic_file_read_iter */
10) ! 181.742 us | } /* blkdev_read_iter */
10) ! 185.747 us | } /* aio_run_iocb */
10) ! 189.350 us | } /* io_submit_one */
10) | blk_finish_plug() {
10) 0.060 us | blk_flush_plug_list();
10) 0.576 us | } /* blk_finish_plug */
10) ! 192.194 us | } /* do_io_submit */
10) ! 192.749 us | } /* SyS_io_submit */
10) | SyS_io_submit() {
10) | do_io_submit() {
10) 0.181 us | lookup_ioctx();
10) 0.060 us | blk_start_plug();
10) | io_submit_one() {
10) | kmem_cache_alloc() {
10) 0.061 us | _cond_resched();
10) 0.062 us | kmemleak_alloc();
10) 1.213 us | } /* kmem_cache_alloc */
10) | fget() {
10) 0.126 us | __fget();
10) 0.638 us | } /* fget */
10) | aio_run_iocb() {
10) | rw_verify_area() {
10) | security_file_permission() {
10) 0.061 us | cap_file_permission();
10) 0.062 us | __fsnotify_parent();
10) 0.072 us | fsnotify();
10) 1.761 us | } /* security_file_permission */
10) 2.312 us | } /* rw_verify_area */
10) 0.068 us | iov_iter_init();
10) | blkdev_read_iter() {
10) | generic_file_read_iter() {
10) 0.064 us | filemap_write_and_wait_range();
10) | blkdev_direct_IO() {
10) | __blockdev_direct_IO() {
10) 0.064 us | iov_iter_alignment();
10) | kmem_cache_alloc() {
10) 0.071 us | _cond_resched();
10) 0.070 us | kmemleak_alloc();
10) 1.467 us | } /* kmem_cache_alloc */
10) 0.072 us | iov_iter_npages();
10) 0.073 us | blk_start_plug();
10) | do_direct_IO() {
10) | iov_iter_get_pages() {
10) | get_user_pages_fast() {
10) | gup_pud_range() {
10) 0.263 us | gup_pte_range();
10) 0.857 us | } /* gup_pud_range */
10) 1.441 us | } /* get_user_pages_fast */
10) 2.043 us | } /* iov_iter_get_pages */
10) ==========> |
10) | do_IRQ() {
10) | irq_enter() {
10) 0.083 us | rcu_irq_enter();
10) 0.110 us | irqtime_account_irq();
10) 1.174 us | } /* irq_enter */
10) 0.068 us | exit_idle();
10) | handle_irq() {
10) 0.089 us | irq_to_desc();
10) | handle_edge_irq() {
10) 0.056 us | _raw_spin_lock();
10) 0.133 us | ir_ack_apic_edge();
10) | handle_irq_event() {
10) | handle_irq_event_percpu() {
10) | do_hpsa_intr_msi [hpsa]() {
10) 0.205 us | SA5_performant_completed [hpsa]();
10) | complete_scsi_command [hpsa]() {
10) 0.161 us | scsi_dma_unmap();
10) | process_ioaccel2_completion [hpsa]() {
10) | scsi_mq_done() {
10) | blk_mq_complete_request() {
10) | __blk_mq_complete_request() {
10) | smp_call_function_single_async() {
10) | generic_exec_single() {
10) | native_send_call_func_single_ipi() {
10) | x2apic_send_IPI_mask() {
10) 0.337 us | __x2apic_send_IPI_mask();
10) 0.855 us | } /* x2apic_send_IPI_mask */
10) 1.385 us | } /* native_send_call_func_single_ipi */
10) 2.072 us | } /* generic_exec_single */
10) 2.708 us | } /* smp_call_function_single_async */
10) 3.347 us | } /* __blk_mq_complete_request */
10) 3.952 us | } /* blk_mq_complete_request */
10) 4.509 us | } /* scsi_mq_done */
10) 5.265 us | } /* process_ioaccel2_completion [hpsa] */
10) 6.650 us | } /* complete_scsi_command [hpsa] */
10) 8.007 us | } /* do_hpsa_intr_msi [hpsa] */
10) 0.089 us | add_interrupt_randomness();
10) 0.072 us | note_interrupt();
10) 9.711 us | } /* handle_irq_event_percpu */
10) 0.062 us | _raw_spin_lock();
10) + 10.808 us | } /* handle_irq_event */
10) + 12.396 us | } /* handle_edge_irq */
10) + 13.472 us | } /* handle_irq */
10) | irq_exit() {
10) 0.097 us | irqtime_account_irq();
10) 0.055 us | idle_cpu();
10) 0.086 us | rcu_irq_exit();
10) 1.773 us | } /* irq_exit */
10) + 18.513 us | } /* do_IRQ */
10) <========== |
10) | smp_call_function_single_interrupt() {
10) | irq_enter() {
10) 0.081 us | rcu_irq_enter();
10) 0.094 us | irqtime_account_irq();
10) 1.307 us | } /* irq_enter */
10) ==========> |
10) | generic_smp_call_function_single_interrupt() {
10) | flush_smp_call_function_queue() {
10) | __blk_mq_complete_request_remote() {
10) | scsi_softirq_done() {
10) | scsi_decide_disposition() {
10) 0.069 us | scsi_handle_queue_ramp_up();
10) 0.693 us | } /* scsi_decide_disposition */
10) 0.062 us | scsi_log_completion();
10) | scsi_finish_command() {
10) 0.113 us | scsi_device_unbusy();
---
Rob Elliott HP Server Storage
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: ftrace function-graph and interprocessor interrupts
2014-09-25 23:10 ` Elliott, Robert (Server Storage)
@ 2014-09-25 23:38 ` Steven Rostedt
0 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2014-09-25 23:38 UTC (permalink / raw)
To: Elliott, Robert (Server Storage)
Cc: Andi Kleen, linux-kernel,
Jens Axboe <axboe@kernel.dk> (axboe@kernel.dk),
Christoph Hellwig, Frederic Weisbecker
On Thu, 25 Sep 2014 23:10:31 +0000
"Elliott, Robert (Server Storage)" <Elliott@hp.com> wrote:
>
>
> > -----Original Message-----
> > From: Steven Rostedt [mailto:rostedt@goodmis.org]
> ...
> > Does, this patch fix it for you?
> >
> > -- Steve
> ...
>
> > - if (type == TRACE_GRAPH_ENT)
> > - ret = trace_seq_puts(s, "==========>");
> > - else
> > + if (trace_flags & TRACE_ITER_LATENCY_FMT) {
> > + ret = print_graph_lat_fmt(s, ent);
> > + if (ret == TRACE_TYPE_PARTIAL_LINE)
> > + return TRACE_TYPE_PARTIAL_LINE;
> > + }
> > +
> > + if (*cpu_in_irq) {
> > ret = trace_seq_puts(s, "<==========");
> > + *cpu_in_irq = 0;
> > + } else {
> > + ret = trace_seq_puts(s, "==========>");
> > + *cpu_in_irq = in_irq;
> > + }
>
> That changes the direction of the arrows (which is fine, if
> intended).
>
No that wasn't intended. Strange, it has the correct directions on my
box :-/
> Results:
> The beginning and end of do_IRQ are marked, but it drops off
> during the middle. The normal function trace shows all of those
> still in hardirq context.
Wasn't that the original behavior? What I did was to use both the
original way and added a check of the in hardirq flag. Since the
functions in the irqentry section don't have the hardirq flag set yet,
when it sees one of those functions it defaults to the old method
(triggering the output of the arrows when it sees those functions.
If it sees the hardirq flag set without being in an irq, it starts the
new way. That is, it prints the arrow when it starts, and prints the
return when the hardirq flag is no longer set.
Now maybe I could switch the method in mid stream. That is, if it is
using the original method (the addr matching the irqentry section), but
hard irqs are still enabled, it could switches to the new method and
print the return when its no longer set. I can try that out.
It's still strange that the arrows are reversed for you??
>
>
> 10) <========== |
> 10) | do_IRQ() {
> 10) | irq_enter() {
> 10) 0.082 us | rcu_irq_enter();
> 10) 0.101 us | irqtime_account_irq();
> 10) 1.321 us | } /* irq_enter */
> 10) ==========> |
> 10) 0.058 us | exit_idle();
> 10) | handle_irq() {
> 10) 0.091 us | irq_to_desc();
> 10) | handle_edge_irq() {
> 10) 0.068 us | _raw_spin_lock();
> 10) 0.142 us | ir_ack_apic_edge();
> 10) | handle_irq_event() {
> 10) | handle_irq_event_percpu() {
> ...
> 10) 0.092 us | add_interrupt_randomness();
> 10) 0.080 us | note_interrupt();
> 10) 9.510 us | } /* handle_irq_event_percpu */
> 10) 0.071 us | _raw_spin_lock();
> 10) + 10.577 us | } /* handle_irq_event */
> 10) + 12.310 us | } /* handle_edge_irq */
> 10) + 13.901 us | } /* handle_irq */
> 10) | irq_exit() {
> 10) 0.111 us | irqtime_account_irq();
> 10) <========== |
> 10) 0.074 us | idle_cpu();
> 10) 0.080 us | rcu_irq_exit();
> 10) 1.800 us | } /* irq_exit */
> 10) + 19.132 us | } /* do_IRQ */
> 10) ==========> |
>
>
> Same with smp_apic_timer_interrupt:
> 10) <========== |
> 10) | smp_apic_timer_interrupt() {
> 10) | irq_enter() {
> 10) 0.072 us | rcu_irq_enter();
> 10) 0.099 us | irqtime_account_irq();
> 10) 1.069 us | } /* irq_enter */
> 10) ==========> |
> 10) 0.060 us | exit_idle();
> 10) | local_apic_timer_interrupt() {
> 10) | hrtimer_interrupt() {
> ...
> 10) 1.810 us | } /* tick_program_event */
> 10) + 32.361 us | } /* hrtimer_interrupt */
> 10) + 32.904 us | } /* local_apic_timer_interrupt */
> 10) | irq_exit() {
> 10) 0.111 us | irqtime_account_irq();
> 10) <========== |
> 10) | __do_softirq() {
> 10) 0.058 us | msecs_to_jiffies();
> 10) 0.099 us | irqtime_account_irq();
> 10) | smp_call_function_single_interrupt() {
> 10) | irq_enter() {
> 10) 0.069 us | rcu_irq_enter();
> 10) 0.100 us | irqtime_account_irq();
> 10) 1.251 us | } /* irq_enter */
> 10) ==========> |
>
>
> generic_smp_call_function_single_interrupt doesn't
> seem to be getting marked, even though function trace
> finds many that are in hardirq context.
>
> fio-7146 [010] d... 2968.183376: smp_call_function_single_interrupt <-call_function_single_interrupt
> fio-7146 [010] d... 2968.183376: irq_enter <-smp_call_function_single_interrupt
> fio-7146 [010] d... 2968.183377: rcu_irq_enter <-irq_enter
> fio-7146 [010] d... 2968.183377: irqtime_account_irq <-irq_enter
> fio-7146 [010] d.h. 2968.183377: generic_smp_call_function_single_interrupt <-smp_call_function_single_interrupt
> fio-7146 [010] d.h. 2968.183377: flush_smp_call_function_queue <-generic_smp_call_function_single_interrupt
> fio-7146 [010] d.h. 2968.183378: __blk_mq_complete_request_remote <-flush_smp_call_function_queue
> fio-7146 [010] d.h. 2968.183378: scsi_softirq_done <-__blk_mq_complete_request_remote
> fio-7146 [010] d.h. 2968.183378: scsi_decide_disposition <-scsi_softirq_done
>
> Here's a longer excerpt starting with back-to-back arrows.
> After that they seem flipped again. This shows a
> generic_smp_call_function_single_interrupt call.
>
>
> 10) 0.079 us | rcu_irq_exit();
> 10) 1.829 us | } /* irq_exit */
> 10) + 26.462 us | } /* do_IRQ */
> 10) <========== |
> 10) ==========> |
Hmm, this could explain the reversal. Did the start of the do_irq get
set? If tracing strarts in the irq, things could get messed up. I'll
have to look at the state machine some more.
> 10) | do_IRQ() {
> 10) | irq_enter() {
> 10) 0.078 us | rcu_irq_enter();
> 10) 0.108 us | irqtime_account_irq();
> 10) 1.200 us | } /* irq_enter */
> 10) 0.053 us | exit_idle();
> 10) | handle_irq() {
> 10) 0.104 us | irq_to_desc();
> 10) | handle_edge_irq() {
> 10) 0.072 us | _raw_spin_lock();
> 10) 0.153 us | ir_ack_apic_edge();
> 10) | handle_irq_event() {
> 10) | handle_irq_event_percpu() {
> 10) | do_hpsa_intr_msi [hpsa]() {
> 10) 0.144 us | SA5_performant_completed [hpsa]();
> 10) 0.749 us | } /* do_hpsa_intr_msi [hpsa] */
> 10) 0.082 us | add_interrupt_randomness();
> 10) 0.075 us | note_interrupt();
> 10) 2.470 us | } /* handle_irq_event_percpu */
> 10) 0.062 us | _raw_spin_lock();
> 10) 3.556 us | } /* handle_irq_event */
> 10) 5.332 us | } /* handle_edge_irq */
> 10) 6.521 us | } /* handle_irq */
> 10) | irq_exit() {
> 10) 0.108 us | irqtime_account_irq();
> 10) 0.060 us | idle_cpu();
> 10) 0.079 us | rcu_irq_exit();
> 10) 1.752 us | } /* irq_exit */
> 10) + 11.513 us | } /* do_IRQ */
> 10) <========== |
> 10) | scsi_init_io() {
> 10) | scsi_init_sgtable() {
> 10) 0.109 us | scsi_alloc_sgtable();
> 10) | blk_rq_map_sg() {
> 10) 0.134 us | __blk_bios_map_sg();
> 10) 0.697 us | } /* blk_rq_map_sg */
> 10) 1.864 us | } /* scsi_init_sgtable */
> 10) 2.436 us | } /* scsi_init_io */
> 10) + 42.767 us | } /* sd_setup_read_write_cmnd [sd_mod] */
> 10) + 43.329 us | } /* sd_init_command [sd_mod] */
> 10) + 43.886 us | } /* scsi_setup_cmnd */
> 10) + 45.100 us | } /* scsi_mq_prep_fn */
> 10) 0.080 us | scsi_init_cmd_errh();
> 10) | scsi_dispatch_cmd() {
> 10) 0.057 us | scsi_log_send();
> 10) | hpsa_scsi_queue_command [hpsa]() {
> 10) 0.125 us | cmd_tagged_alloc [hpsa]();
> 10) | hpsa_ioaccel_submit [hpsa]() {
> 10) 0.193 us | hpsa_cmd_init [hpsa]();
> 10) | hpsa_scsi_ioaccel_queue_command [hpsa]() {
> 10) | hpsa_scsi_ioaccel2_queue_command [hpsa]() {
> 10) 0.057 us | fixup_ioaccel_cdb [hpsa]();
> 10) 0.112 us | scsi_dma_map();
> 10) | enqueue_cmd_and_start_io [hpsa]() {
> 10) 0.087 us | __enqueue_cmd_and_start_io [hpsa]();
> 10) 0.701 us | } /* enqueue_cmd_and_start_io [hpsa] */
> 10) 2.627 us | } /* hpsa_scsi_ioaccel2_queue_command [hpsa] */
> 10) 3.146 us | } /* hpsa_scsi_ioaccel_queue_command [hpsa] */
> 10) 4.394 us | } /* hpsa_ioaccel_submit [hpsa] */
> 10) 5.909 us | } /* hpsa_scsi_queue_command [hpsa] */
> 10) 7.034 us | } /* scsi_dispatch_cmd */
> 10) + 54.950 us | } /* scsi_queue_rq */
> 10) + 60.213 us | } /* __blk_mq_run_hw_queue */
> 10) + 60.760 us | } /* blk_mq_run_hw_queue */
> 10) ! 112.938 us | } /* blk_sq_make_request */
> 10) ! 115.912 us | } /* generic_make_request */
> 10) ! 116.470 us | } /* submit_bio */
> 10) | blk_finish_plug() {
> 10) 0.063 us | blk_flush_plug_list();
> 10) 0.695 us | } /* blk_finish_plug */
> 10) 0.104 us | _raw_spin_lock_irqsave();
> 10) 0.086 us | _raw_spin_unlock_irqrestore();
> 10) ! 179.456 us | } /* __blockdev_direct_IO */
> 10) ! 180.009 us | } /* blkdev_direct_IO */
> 10) ! 181.178 us | } /* generic_file_read_iter */
> 10) ! 181.742 us | } /* blkdev_read_iter */
> 10) ! 185.747 us | } /* aio_run_iocb */
> 10) ! 189.350 us | } /* io_submit_one */
> 10) | blk_finish_plug() {
> 10) 0.060 us | blk_flush_plug_list();
> 10) 0.576 us | } /* blk_finish_plug */
> 10) ! 192.194 us | } /* do_io_submit */
> 10) ! 192.749 us | } /* SyS_io_submit */
> 10) | SyS_io_submit() {
> 10) | do_io_submit() {
> 10) 0.181 us | lookup_ioctx();
> 10) 0.060 us | blk_start_plug();
> 10) | io_submit_one() {
> 10) | kmem_cache_alloc() {
> 10) 0.061 us | _cond_resched();
> 10) 0.062 us | kmemleak_alloc();
> 10) 1.213 us | } /* kmem_cache_alloc */
> 10) | fget() {
> 10) 0.126 us | __fget();
> 10) 0.638 us | } /* fget */
> 10) | aio_run_iocb() {
> 10) | rw_verify_area() {
> 10) | security_file_permission() {
> 10) 0.061 us | cap_file_permission();
> 10) 0.062 us | __fsnotify_parent();
> 10) 0.072 us | fsnotify();
> 10) 1.761 us | } /* security_file_permission */
> 10) 2.312 us | } /* rw_verify_area */
> 10) 0.068 us | iov_iter_init();
> 10) | blkdev_read_iter() {
> 10) | generic_file_read_iter() {
> 10) 0.064 us | filemap_write_and_wait_range();
> 10) | blkdev_direct_IO() {
> 10) | __blockdev_direct_IO() {
> 10) 0.064 us | iov_iter_alignment();
> 10) | kmem_cache_alloc() {
> 10) 0.071 us | _cond_resched();
> 10) 0.070 us | kmemleak_alloc();
> 10) 1.467 us | } /* kmem_cache_alloc */
> 10) 0.072 us | iov_iter_npages();
> 10) 0.073 us | blk_start_plug();
> 10) | do_direct_IO() {
> 10) | iov_iter_get_pages() {
> 10) | get_user_pages_fast() {
> 10) | gup_pud_range() {
> 10) 0.263 us | gup_pte_range();
> 10) 0.857 us | } /* gup_pud_range */
> 10) 1.441 us | } /* get_user_pages_fast */
> 10) 2.043 us | } /* iov_iter_get_pages */
> 10) ==========> |
> 10) | do_IRQ() {
> 10) | irq_enter() {
> 10) 0.083 us | rcu_irq_enter();
> 10) 0.110 us | irqtime_account_irq();
> 10) 1.174 us | } /* irq_enter */
> 10) 0.068 us | exit_idle();
> 10) | handle_irq() {
> 10) 0.089 us | irq_to_desc();
> 10) | handle_edge_irq() {
> 10) 0.056 us | _raw_spin_lock();
> 10) 0.133 us | ir_ack_apic_edge();
> 10) | handle_irq_event() {
> 10) | handle_irq_event_percpu() {
> 10) | do_hpsa_intr_msi [hpsa]() {
> 10) 0.205 us | SA5_performant_completed [hpsa]();
> 10) | complete_scsi_command [hpsa]() {
> 10) 0.161 us | scsi_dma_unmap();
> 10) | process_ioaccel2_completion [hpsa]() {
> 10) | scsi_mq_done() {
> 10) | blk_mq_complete_request() {
> 10) | __blk_mq_complete_request() {
> 10) | smp_call_function_single_async() {
> 10) | generic_exec_single() {
> 10) | native_send_call_func_single_ipi() {
> 10) | x2apic_send_IPI_mask() {
> 10) 0.337 us | __x2apic_send_IPI_mask();
> 10) 0.855 us | } /* x2apic_send_IPI_mask */
> 10) 1.385 us | } /* native_send_call_func_single_ipi */
> 10) 2.072 us | } /* generic_exec_single */
> 10) 2.708 us | } /* smp_call_function_single_async */
> 10) 3.347 us | } /* __blk_mq_complete_request */
> 10) 3.952 us | } /* blk_mq_complete_request */
> 10) 4.509 us | } /* scsi_mq_done */
> 10) 5.265 us | } /* process_ioaccel2_completion [hpsa] */
> 10) 6.650 us | } /* complete_scsi_command [hpsa] */
> 10) 8.007 us | } /* do_hpsa_intr_msi [hpsa] */
> 10) 0.089 us | add_interrupt_randomness();
> 10) 0.072 us | note_interrupt();
> 10) 9.711 us | } /* handle_irq_event_percpu */
> 10) 0.062 us | _raw_spin_lock();
> 10) + 10.808 us | } /* handle_irq_event */
> 10) + 12.396 us | } /* handle_edge_irq */
> 10) + 13.472 us | } /* handle_irq */
> 10) | irq_exit() {
> 10) 0.097 us | irqtime_account_irq();
> 10) 0.055 us | idle_cpu();
> 10) 0.086 us | rcu_irq_exit();
> 10) 1.773 us | } /* irq_exit */
> 10) + 18.513 us | } /* do_IRQ */
> 10) <========== |
Hmm, one interrupt followed by another could screw this up.
Anyway, I need to put this into the back burner. It's not that critical
of a bug, and there's other fish to fry on the front burners.
-- Steve
> 10) | smp_call_function_single_interrupt() {
> 10) | irq_enter() {
> 10) 0.081 us | rcu_irq_enter();
> 10) 0.094 us | irqtime_account_irq();
> 10) 1.307 us | } /* irq_enter */
> 10) ==========> |
> 10) | generic_smp_call_function_single_interrupt() {
> 10) | flush_smp_call_function_queue() {
> 10) | __blk_mq_complete_request_remote() {
> 10) | scsi_softirq_done() {
> 10) | scsi_decide_disposition() {
> 10) 0.069 us | scsi_handle_queue_ramp_up();
> 10) 0.693 us | } /* scsi_decide_disposition */
> 10) 0.062 us | scsi_log_completion();
> 10) | scsi_finish_command() {
> 10) 0.113 us | scsi_device_unbusy();
>
> ---
> Rob Elliott HP Server Storage
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-09-25 23:38 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-09-24 21:14 ftrace function-graph and interprocessor interrupts Elliott, Robert (Server Storage)
2014-09-24 21:49 ` Andi Kleen
2014-09-24 22:02 ` Elliott, Robert (Server Storage)
2014-09-25 20:38 ` Steven Rostedt
2014-09-25 23:10 ` Elliott, Robert (Server Storage)
2014-09-25 23:38 ` Steven Rostedt
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