From: Peter Zijlstra <peterz@infradead.org>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ingo Molnar <mingo@kernel.org>,
Byungchul Park <byungchul.park@lge.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Luca Abeni <luca.abeni@unitn.it>, Rik van Riel <riel@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Wanpeng Li <wanpeng.li@hotmail.com>,
Yuyang Du <yuyang.du@intel.com>, Petr Mladek <pmladek@suse.com>,
Jan Kara <jack@suse.cz>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-kernel@vger.kernel.org,
Mel Gorman <mgorman@techsingularity.net>,
Mike Galbraith <umgwanakikbuti@gmail.com>
Subject: Re: [PATCH v2 1/7] sched/fair: Update the rq clock before detaching tasks
Date: Mon, 3 Oct 2016 14:49:07 +0200 [thread overview]
Message-ID: <20161003124907.GD3142@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160921133813.31976-2-matt@codeblueprint.co.uk>
On Wed, Sep 21, 2016 at 02:38:07PM +0100, Matt Fleming wrote:
> detach_task_cfs_rq() may indirectly call rq_clock() to inform the
> cpufreq code that the rq utilisation has changed. In which case, we
> need to update the rq clock.
Hurm,. so it would've been good to know the callchain that got you
there.
There's two functions that use detach_task_cfs_rq(), one is through
sched_change_group() and that does indeed lack a rq_clock update.
The other is through switched_from() where its far harder (but still
possible afaict) to miss the update.
Now, neither cases are really fast paths, but it would be good to try
and avoid too many update_rq_clock() calls in the same rq-lock section.
So I'm not entirely sure about the placement here.
But let me go stare at the actual debug framework thing first.. I think
this patch is fallout/fixups from that.
next prev parent reply other threads:[~2016-10-03 12:49 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 13:38 [PATCH v2 0/7] sched: Diagnostic checks for missing rq clock updates Matt Fleming
2016-09-21 13:38 ` [PATCH v2 1/7] sched/fair: Update the rq clock before detaching tasks Matt Fleming
2016-10-03 12:49 ` Peter Zijlstra [this message]
2016-10-03 14:37 ` Matt Fleming
2016-10-03 14:42 ` Peter Zijlstra
2016-09-21 13:38 ` [PATCH v2 2/7] sched/fair: Update rq clock before waking up new task Matt Fleming
2016-09-21 13:38 ` [PATCH v2 3/7] sched/fair: Update rq clock in task_hot() Matt Fleming
2016-09-21 13:38 ` [PATCH v2 4/7] sched: Add wrappers for lockdep_(un)pin_lock() Matt Fleming
2017-01-14 12:40 ` [tip:sched/core] sched/core: " tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 5/7] sched/core: Reset RQCF_ACT_SKIP before unpinning rq->lock Matt Fleming
2017-01-14 12:41 ` [tip:sched/core] " tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 6/7] sched/fair: Push rq lock pin/unpin into idle_balance() Matt Fleming
2017-01-14 12:41 ` [tip:sched/core] " tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 7/7] sched/core: Add debug code to catch missing update_rq_clock() Matt Fleming
2016-09-21 15:58 ` Petr Mladek
2016-09-21 19:08 ` Matt Fleming
2016-09-21 19:46 ` Thomas Gleixner
2016-09-22 0:44 ` Sergey Senozhatsky
2016-09-22 8:04 ` Peter Zijlstra
2016-09-22 8:36 ` Jan Kara
2016-09-22 9:39 ` Peter Zijlstra
2016-09-22 10:17 ` Peter Zijlstra
2017-01-14 12:44 ` [tip:sched/core] sched/core: Add debugging code to catch missing update_rq_clock() calls tip-bot for Matt Fleming
2017-01-30 21:24 ` Michael Ellerman
2017-01-30 21:24 ` Michael Ellerman
2017-01-30 21:34 ` Matt Fleming
2017-01-31 8:35 ` Michael Ellerman
2017-01-31 8:35 ` Michael Ellerman
2017-01-31 11:00 ` Sachin Sant
2017-01-31 11:00 ` Sachin Sant
2017-01-31 11:00 ` Sachin Sant
2017-01-31 11:48 ` Mike Galbraith
2017-01-31 11:48 ` Mike Galbraith
2017-01-31 11:48 ` Mike Galbraith
2017-01-31 17:22 ` Ross Zwisler
2017-01-31 17:22 ` Ross Zwisler
2017-02-02 15:55 ` Peter Zijlstra
2017-02-02 22:01 ` Matt Fleming
2017-02-03 3:05 ` Mike Galbraith
2017-02-03 4:33 ` Sachin Sant
2017-02-03 4:33 ` Sachin Sant
2017-02-03 8:53 ` Peter Zijlstra
2017-02-03 8:53 ` Peter Zijlstra
2017-02-03 11:04 ` Sachin Sant
2017-02-03 11:04 ` Sachin Sant
2017-02-03 12:59 ` Mike Galbraith
2017-02-03 13:37 ` Peter Zijlstra
2017-02-03 13:52 ` Mike Galbraith
2017-02-03 15:44 ` Paul E. McKenney
2017-02-03 15:54 ` Paul E. McKenney
2017-02-06 6:23 ` Sachin Sant
2017-02-06 6:23 ` Sachin Sant
2017-02-06 15:10 ` Paul E. McKenney
2017-02-06 15:14 ` Paul E. McKenney
2017-02-03 13:04 ` Borislav Petkov
2017-02-22 9:03 ` Wanpeng Li
2017-02-24 9:16 ` [tip:sched/urgent] sched/core: Fix update_rq_clock() splat on hotplug (and suspend/resume) tip-bot for Peter Zijlstra
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