From: Valdis.Kletnieks@vt.edu
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Lameter <cl@gentwo.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [RFC][PATCH 0/5] Introduce checks for preemptable code for this_cpu_read/write()
Date: Tue, 20 Sep 2011 18:17:52 -0400 [thread overview]
Message-ID: <25599.1316557072@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Tue, 20 Sep 2011 11:19:47 EDT." <1316531987.29966.65.camel@gandalf.stny.rr.com>
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On Tue, 20 Sep 2011 11:19:47 EDT, Steven Rostedt said:
> On Tue, 2011-09-20 at 09:57 -0500, Christoph Lameter wrote:
>
> > this_cpu_xx functions are made for those locations that have
> > preemption enabled. If you can use those function (classic case is a
> > per cpu counter increment in the network subsystem) then you can avoid
> > preempt disable/enable or get_cpu/put_cpu.
>
> If the variables are used for a very short time, then the latencies
> introduced by a simple:
>
> var = get_cpu_var(my_var);
> if (var)
> do_something_quick();
> put_cpu_var(my_var);
>
> Otherwise if that do_something_quick(); migrates, it may be doing
> something it shouldn't be doing!
This has the added advantage of making the calling function take the blame
in latency traces, doesn't it?
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next prev parent reply other threads:[~2011-09-20 22:19 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-19 21:20 Steven Rostedt
2011-09-19 21:20 ` [RFC][PATCH 1/5] x86: Remove const_udelay() caring about which cpu var it uses Steven Rostedt
2011-09-19 21:51 ` Christoph Lameter
2011-09-19 23:31 ` Steven Rostedt
2011-09-19 21:20 ` [RFC][PATCH 2/5] mm: Switch mod_state() to __this_cpu_read() Steven Rostedt
2011-09-19 22:02 ` Christoph Lameter
2011-09-19 23:48 ` Steven Rostedt
2011-09-20 14:46 ` Christoph Lameter
2011-09-20 15:16 ` Steven Rostedt
2011-09-20 15:54 ` Christoph Lameter
2011-09-20 16:07 ` Steven Rostedt
2011-09-20 22:19 ` Valdis.Kletnieks
2011-09-20 13:49 ` Thomas Gleixner
2011-09-20 14:01 ` Steven Rostedt
2011-09-20 14:51 ` Christoph Lameter
2011-09-20 15:11 ` Steven Rostedt
2011-09-20 15:59 ` Christoph Lameter
2011-09-20 16:03 ` Steven Rostedt
2011-09-20 16:07 ` Christoph Lameter
2011-09-20 15:27 ` Thomas Gleixner
2011-09-20 16:02 ` Christoph Lameter
2011-09-20 16:51 ` Thomas Gleixner
2011-09-20 17:08 ` Steven Rostedt
2011-09-19 21:20 ` [RFC][PATCH 3/5] memcg: Disable preemption in memcg_check_events() Steven Rostedt
2011-09-20 14:20 ` Johannes Weiner
2011-09-20 14:24 ` Johannes Weiner
2011-09-20 14:33 ` Steven Rostedt
2011-09-24 0:46 ` Steven Rostedt
2011-09-19 21:20 ` [RFC][PATCH 4/5] printk: Have wake_up_klogd() use __this_cpu_write() Steven Rostedt
2011-09-19 21:54 ` Christoph Lameter
2011-09-19 23:33 ` Steven Rostedt
2011-09-20 14:54 ` Christoph Lameter
2011-09-20 14:55 ` Peter Zijlstra
2011-09-19 21:20 ` [RFC][PATCH 5/5] percpu: Add preempt checks back into this_cpu_read/write() Steven Rostedt
2011-09-19 21:49 ` [RFC][PATCH 0/5] Introduce checks for preemptable code for this_cpu_read/write() Christoph Lameter
2011-09-20 3:06 ` Steven Rostedt
2011-09-20 12:44 ` Valdis.Kletnieks
2011-09-20 13:51 ` Thomas Gleixner
2011-09-20 14:58 ` Christoph Lameter
2011-09-20 15:17 ` Steven Rostedt
2011-09-20 14:57 ` Christoph Lameter
2011-09-20 15:19 ` Steven Rostedt
2011-09-20 16:08 ` Christoph Lameter
2011-09-20 16:31 ` Steven Rostedt
2011-09-20 16:56 ` Steven Rostedt
2011-09-20 17:09 ` Peter Zijlstra
2011-09-20 17:15 ` Steven Rostedt
2011-09-20 17:25 ` Mathieu Desnoyers
2011-09-20 18:03 ` Steven Rostedt
2011-09-20 18:12 ` Mathieu Desnoyers
2011-09-20 18:27 ` Steven Rostedt
2011-09-20 18:34 ` Mathieu Desnoyers
2011-09-20 22:32 ` Valdis.Kletnieks
2011-09-20 22:17 ` Valdis.Kletnieks [this message]
2011-09-21 1:33 ` Steven Rostedt
2011-09-20 15:46 ` Mathieu Desnoyers
2011-09-20 16:00 ` Steven Rostedt
2011-09-20 16:10 ` Christoph Lameter
2011-09-20 16:50 ` Peter Zijlstra
2011-09-20 18:54 ` Steven Rostedt
2011-09-21 15:16 ` Christoph Lameter
2011-09-21 15:31 ` Steven Rostedt
2011-09-21 15:59 ` Christoph Lameter
2011-09-21 16:12 ` Steven Rostedt
2011-09-21 16:32 ` Thomas Gleixner
2011-09-20 2:20 ` Andi Kleen
2011-09-20 3:12 ` Steven Rostedt
2011-09-20 3:17 ` Steven Rostedt
2011-09-20 8:32 ` Thomas Gleixner
2011-09-20 12:10 ` Steven Rostedt
2011-09-20 15:03 ` Christoph Lameter
2011-09-20 15:07 ` Peter Zijlstra
2011-09-20 16:05 ` Christoph Lameter
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