From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Wanpeng Li <wanpengli@tencent.com>,
Thomas Gleixner <tglx@linutronix.de>,
Yauheni Kaliuta <yauheni.kaliuta@redhat.com>,
Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 19/25] sched/vite: Handle nice updates under vtime
Date: Mon, 26 Nov 2018 17:11:03 +0100 [thread overview]
Message-ID: <20181126161103.GW2131@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181126155352.GA18962@lerouge>
On Mon, Nov 26, 2018 at 04:53:54PM +0100, Frederic Weisbecker wrote:
> > > + irq_work_queue_on(&per_cpu(vtime_set_nice_work, cpu), cpu);
> >
> > What happens if you already had one pending? Do we loose updates?
>
> No, if irq_work is already pending, it doesn't requeue iff the work hasn't
> been executed yet and it's guaranteed it will see the freshest update.
> (you should trust more the code you wrote ;-)
Yeah, I do remember hoq irq_work works. What I was asking was about how
this specific handler deals with 'missing' updates.
Suppose we start with state A, set it to B and raise the IPI, then set
it to C before the interrupt happens.
That means the irq_work handler will see C and never observe B.
next prev parent reply other threads:[~2018-11-26 16:11 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 2:45 [PATCH 00/25] sched/nohz: Make kcpustat vtime aware (Fix kcpustat on nohz_full) Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 01/25] sched/vtime: Fix guest/system mis-accounting on task switch Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 02/25] sched/vtime: Protect idle accounting under vtime seqcount Frederic Weisbecker
2018-11-20 13:19 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 03/25] vtime: Rename vtime_account_system() to vtime_account_kernel() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 04/25] vtime: Spare a seqcount lock/unlock cycle on context switch Frederic Weisbecker
2018-11-20 13:25 ` Peter Zijlstra
2019-09-25 14:42 ` Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 05/25] sched/vtime: Record CPU under seqcount for kcpustat needs Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 06/25] sched/cputime: Add vtime idle task state Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 07/25] sched/cputime: Add vtime guest " Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 08/25] vtime: Exit vtime before exit_notify() Frederic Weisbecker
2018-11-20 13:54 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 09/25] kcpustat: Track running task following vtime sequences Frederic Weisbecker
2018-11-20 13:58 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 10/25] context_tracking: Remove context_tracking_active() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 11/25] context_tracking: s/context_tracking_is_enabled/context_tracking_enabled() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 12/25] context_tracking: Rename context_tracking_is_cpu_enabled() to context_tracking_enabled_this_cpu() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 13/25] context_tracking: Introduce context_tracking_enabled_cpu() Frederic Weisbecker
2018-11-20 14:02 ` Peter Zijlstra
2018-11-14 2:45 ` [PATCH 14/25] sched/vtime: Rename vtime_accounting_cpu_enabled() to vtime_accounting_enabled_this_cpu() Frederic Weisbecker
2018-11-14 2:45 ` [PATCH 15/25] sched/vtime: Introduce vtime_accounting_enabled_cpu() Frederic Weisbecker
2018-11-20 14:04 ` Peter Zijlstra
2018-11-14 2:46 ` [PATCH 16/25] sched/cputime: Allow to pass cputime index on user/guest accounting Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 17/25] sched/cputime: Standardize the kcpustat index based accounting functions Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 18/25] vtime: Track nice-ness on top of context switch Frederic Weisbecker
2018-11-20 14:09 ` Peter Zijlstra
2018-11-14 2:46 ` [PATCH 19/25] sched/vite: Handle nice updates under vtime Frederic Weisbecker
2018-11-20 14:17 ` Peter Zijlstra
2018-11-26 15:53 ` Frederic Weisbecker
2018-11-26 16:11 ` Peter Zijlstra [this message]
2018-11-26 18:41 ` Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 20/25] sched/kcpustat: Introduce vtime-aware kcpustat accessor Frederic Weisbecker
2018-11-20 14:23 ` Peter Zijlstra
2018-11-20 22:40 ` Frederic Weisbecker
2018-11-21 8:18 ` Peter Zijlstra
2018-11-21 8:35 ` Peter Zijlstra
2018-11-21 16:33 ` Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 21/25] procfs: Use vtime aware " Frederic Weisbecker
2018-11-20 14:24 ` Peter Zijlstra
2018-11-20 22:31 ` Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 22/25] cpufreq: " Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 23/25] leds: Use vtime aware kcpustat accessors Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 24/25] rackmeter: " Frederic Weisbecker
2018-11-14 2:46 ` [PATCH 25/25] sched/vtime: Clarify vtime_task_switch() argument layout Frederic Weisbecker
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