From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Boqun Feng <boqun.feng@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Will Deacon <will@kernel.org>, paulmck <paulmck@kernel.org>,
Nicholas Piggin <npiggin@gmail.com>,
Andy Lutomirski <luto@amacapital.net>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 2/3] sched: membarrier: cover kthread_use_mm (v3)
Date: Wed, 7 Oct 2020 18:08:20 +0200 [thread overview]
Message-ID: <20201007160820.GK2628@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1286784649.11153.1602085170586.JavaMail.zimbra@efficios.com>
On Wed, Oct 07, 2020 at 11:39:30AM -0400, Mathieu Desnoyers wrote:
> Moving the membarrier_switch_mm to cover kthread cases was to ensure (2), but if we
> add a p->mm NULL check in the global expedited iteration, I think we would be OK
> leaving the stale runqueue's membarrier state while in lazy tlb state.
>
> As far as (1) is concerned, I think your idea would work, because as you say we will
> have the proper barriers in kthread use/unuse mm.
>
> I just wonder whether having this stale membarrier state for lazy tlb is warranted
> performance-wise, as it adds complexity: the rq membarrier state will therefore not be
> relevant when we are in lazy tlb mode.
>
> Thoughts ?
Well, the way I got here was that I considered the membarrier state
update tied to switch_mm(), and in that regard my proposal is a
simplification.
next prev parent reply other threads:[~2020-10-07 16:08 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 17:25 [RFC PATCH 0/3] Membarrier updates Mathieu Desnoyers
2020-09-24 17:25 ` [RFC PATCH 1/3] sched: fix exit_mm vs membarrier (v3) Mathieu Desnoyers
2020-10-07 14:29 ` Peter Zijlstra
2020-10-07 14:57 ` Mathieu Desnoyers
2020-10-07 15:09 ` Peter Zijlstra
2020-09-24 17:25 ` [RFC PATCH 2/3] sched: membarrier: cover kthread_use_mm (v3) Mathieu Desnoyers
2020-10-02 8:33 ` [sched] bdfcae1140: will-it-scale.per_thread_ops -37.0% regression kernel test robot
2020-10-07 14:50 ` Mathieu Desnoyers
2020-10-20 3:24 ` [LKP] " Xing Zhengjun
2020-10-20 13:14 ` Mathieu Desnoyers
2020-10-22 1:54 ` Xing Zhengjun
2020-10-22 13:19 ` Mathieu Desnoyers
2020-10-23 5:37 ` Xing Zhengjun
2020-10-23 12:34 ` Mathieu Desnoyers
2020-10-07 15:07 ` [RFC PATCH 2/3] sched: membarrier: cover kthread_use_mm (v3) Peter Zijlstra
2020-10-07 15:39 ` Mathieu Desnoyers
2020-10-07 16:08 ` Peter Zijlstra [this message]
2020-10-07 16:11 ` Mathieu Desnoyers
2020-09-24 17:25 ` [RFC PATCH 3/3] sched: membarrier: document memory ordering scenarios Mathieu Desnoyers
2020-09-29 17:16 ` [RFC PATCH 0/3] Membarrier updates Mathieu Desnoyers
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