From: Daniel Bristot de Oliveira <bristot@redhat.com>
To: "Vineeth Pillai (Google)" <vineeth@bitbyteword.org>,
Daniel Bristot de Oliveira <bristot@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
linux-kernel@vger.kernel.org,
Luca Abeni <luca.abeni@santannapisa.it>,
Tommaso Cucinotta <tommaso.cucinotta@santannapisa.it>,
Thomas Gleixner <tglx@linutronix.de>,
Joel Fernandes <joel@joelfernandes.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Phil Auld <pauld@redhat.com>,
Suleiman Souhlal <suleiman@google.com>,
Youssef Esmat <youssefesmat@google.com>
Subject: Re: [PATCH] sched/fair: fix dlserver duplicate start and stop
Date: Wed, 24 Apr 2024 18:56:08 +0200 [thread overview]
Message-ID: <99c1761a-9c00-4167-86e5-8a69cb6d9e5d@redhat.com> (raw)
In-Reply-To: <20240412192304.3201847-1-vineeth@bitbyteword.org>
On 4/12/24 21:23, Vineeth Pillai (Google) wrote:
> dlserver is started when a cfs task is enqueued to an empty runqueue.
> Similarly dlserver is stopped when the last cfs task is dequeued. But
> this logic doesn't take care of the cfs throttling scenarios where the
> root cfs runqueue's h_nr_running stays zero while enqueue/dequeue can
> happen on throttled runqueues. This causes duplicate calls to start/stop
> and causes issues with deadline logic. One example is a WARN_ON in
> task_non_contending because of duplicate calls to dl_server_stop().
>
> WARNING kernel: [ 1970.747755] ------------[ cut here ]------------
> WARNING kernel: [ 1970.747767] WARNING: CPU: 0 PID: 14202 at kernel/sched/deadline.c:352 task_non_contending+0x404/0x500
>
> WARNING kernel: [ 1970.747868] CPU: 0 PID: 14202 Comm: tpm_manager_cli Tainted: G W 5.15.152-22017-ga797d64dcd15 #1
> WARNING kernel: [ 1970.747874] Hardware name: HP Meep/Meep, BIOS Google_Meep.11297.250.0 01/25/2021
> WARNING kernel: [ 1970.747877] RIP: 0010:task_non_contending+0x404/0x500
>
> WARNING kernel: [ 1970.747910] Call Trace:
> WARNING kernel: [ 1970.747914] <TASK>
> WARNING kernel: [ 1970.747918] ? __warn+0xa3/0x131
> WARNING kernel: [ 1970.747923] ? task_non_contending+0x404/0x500
> WARNING kernel: [ 1970.747927] ? report_bug+0x97/0xfa
> WARNING kernel: [ 1970.747932] ? handle_bug+0x41/0x66
> WARNING kernel: [ 1970.747937] ? exc_invalid_op+0x1b/0x4b
> WARNING kernel: [ 1970.747941] ? asm_exc_invalid_op+0x16/0x20
> WARNING kernel: [ 1970.747946] ? task_non_contending+0x404/0x500
> WARNING kernel: [ 1970.747949] ? dequeue_dl_entity+0x112/0x2cd
> WARNING kernel: [ 1970.747952] dl_server_stop+0x17/0x2b
> WARNING kernel: [ 1970.747956] dequeue_task_fair+0x262/0x4c4
> WARNING kernel: [ 1970.747962] __schedule+0x17c/0xf13
> WARNING kernel: [ 1970.747966] ? update_load_avg+0x9b/0x611
> WARNING kernel: [ 1970.747970] schedule+0x4e/0xd0
> WARNING kernel: [ 1970.747974] schedule_hrtimeout_range_clock+0x10f/0x126
> WARNING kernel: [ 1970.747977] ? add_wait_queue+0x4d/0x84
> WARNING kernel: [ 1970.747982] poll_schedule_timeout+0x33/0x50
> WARNING kernel: [ 1970.747987] do_sys_poll+0x4a3/0x626
> WARNING kernel: [ 1970.747993] ? __se_sys_ppoll+0xdf/0xdf
> WARNING kernel: [ 1970.748000] __se_sys_poll+0x70/0xf7
> WARNING kernel: [ 1970.748003] do_syscall_64+0x51/0xa1
> WARNING kernel: [ 1970.748007] entry_SYSCALL_64_after_hwframe+0x5c/0xc6
> WARNING kernel: [ 1970.748012] RIP: 0033:0x7bc815769510
I saw that as well.... but from a robot.. not with a reproducer.
> dlserver should be started on an idle root cfs rq, when
> - enqueue on a non-throttled cfs_rq causing the root cfs rq to
> go non-idle, or
> - untthrottle results in the root cfs rq to go non-idle.
>
> Similarly dlserver should be stopped on a non-idle root cfs rq, when
> - dequeue on a non-throttled cfs_rq causing the root cfs rq to
> go idle, or
> - throttle results in the root cfs rq to go idle.
seem to make sense, I will add this check on v7.
Btw, as this is an ongoing thread discussion, instead of sending a patch, next time,
please reply to the patchset... it is easier for everybody to keep track.
-- Daniel
next prev parent reply other threads:[~2024-04-24 16:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-12 19:23 Vineeth Pillai (Google)
2024-04-24 16:56 ` Daniel Bristot de Oliveira [this message]
2024-04-24 21:59 ` Vineeth Remanan Pillai
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