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From: Rik van Riel <riel@surriel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <longman@redhat.com>, Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Phil Auld <pauld@redhat.com>, Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v2] sched/core: Don't use dying mm as active_mm of kthreads
Date: Mon, 29 Jul 2019 12:10:12 -0400	[thread overview]
Message-ID: <aba144fbb176666a479420eb75e5d2032a893c83.camel@surriel.com> (raw)
In-Reply-To: <20190729154419.GJ31398@hirez.programming.kicks-ass.net>

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On Mon, 2019-07-29 at 17:44 +0200, Peter Zijlstra wrote:
> On Mon, Jul 29, 2019 at 11:28:04AM -0400, Rik van Riel wrote:
> > On Mon, 2019-07-29 at 17:03 +0200, Peter Zijlstra wrote:
> > 
> > > The 'sad' part is that x86 already switches to init_mm on idle
> > > and we
> > > only keep the active_mm around for 'stupid'.
> > 
> > Wait, where do we do that?
> 
> drivers/idle/intel_idle.c:              leave_mm(cpu);
> drivers/acpi/processor_idle.c:  acpi_unlazy_tlb(smp_processor_id());

This is only done for deeper c-states, isn't it?

> > > Rik and Andy were working on getting that 'fixed' a while ago,
> > > not
> > > sure
> > > where that went.
> > 
> > My lazy TLB stuff got merged last year. 
> 
> Yes, but we never got around to getting rid of active_mm for x86,
> right?

True, we still use active_mm. Getting rid of the
active_mm refcounting alltogether did not look
entirely worthwhile the hassle.

-- 
All Rights Reversed.

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  reply	other threads:[~2019-07-29 16:10 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-27 17:10 [PATCH v2] sched/core: Don't use dying mm as active_mm of kthreads Waiman Long
2019-07-29  8:18 ` Qais Yousef
2019-07-29 21:06   ` Waiman Long
2019-07-29 21:33     ` Qais Yousef
2019-07-29  8:52 ` Peter Zijlstra
2019-07-29 14:24   ` [PATCH] sched: Clean up active_mm reference counting Peter Zijlstra
2019-07-29 15:01     ` Mathieu Desnoyers
2019-07-29 15:16     ` Waiman Long
2019-07-29 15:22       ` Peter Zijlstra
2019-07-29 15:29     ` Rik van Riel
2019-07-29 14:27   ` [PATCH v2] sched/core: Don't use dying mm as active_mm of kthreads Peter Zijlstra
2019-07-29 15:22     ` Waiman Long
2019-07-29 15:38       ` Peter Zijlstra
2019-07-29 14:51   ` Waiman Long
2019-07-29 15:03     ` Peter Zijlstra
2019-07-29 15:28       ` Rik van Riel
2019-07-29 15:44         ` Peter Zijlstra
2019-07-29 16:10           ` Rik van Riel [this message]
2019-07-29 16:26             ` Peter Zijlstra
2019-07-29 15:37       ` Waiman Long
2019-07-29 16:12         ` Rik van Riel
2019-07-29 16:22       ` Andy Lutomirski
2019-07-29  9:12 ` Michal Hocko
2019-07-29 15:27   ` Waiman Long
2019-07-29 18:58     ` Michal Hocko
2019-07-29 20:41       ` Waiman Long

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