From: Rik van Riel <riel@surriel.com>
To: Peter Zijlstra <peterz@infradead.org>, Mike Galbraith <efault@gmx.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Andy Lutomirski <luto@kernel.org>
Subject: Re: 4.13..4.14 scheduling overhead regression (bisected - b956575bed91)
Date: Fri, 01 Jun 2018 14:56:29 -0400 [thread overview]
Message-ID: <1527879389.7898.84.camel@surriel.com> (raw)
In-Reply-To: <20180601132055.GT12198@hirez.programming.kicks-ass.net>
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On Fri, 2018-06-01 at 15:20 +0200, Peter Zijlstra wrote:
> On Fri, Jun 01, 2018 at 02:57:53PM +0200, Mike Galbraith wrote:
> > b956575bed91ecfb136a8300742ecbbf451471ab is the first bad commit
> > commit b956575bed91ecfb136a8300742ecbbf451471ab
> > Author: Andy Lutomirski <luto@kernel.org>
> > Date: Mon Oct 9 09:50:49 2017 -0700
> >
> > x86/mm: Flush more aggressively in lazy TLB mode
>
> Oh boy... Maybe we should start looking at that optimization Andy
> mentioned.
>
> IIRC all page freeing does indeed go through tlb_remove_page(), it
> shouldn't be too hard to make that work.
Page freeing does. However, page table freeing
does not, and might need to be done in a different
way.
I wonder how expensive/effective it would be to free
page tables with RCU, and have the RCU code flush the
TLB if it notices the ctx_id is wrong?
Also, I need to go find Andy's optimization, and
see how it works :)
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next prev parent reply other threads:[~2018-06-01 18:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-01 12:57 4.13..4.14 scheduling overhead regression (bisected - b956575bed91) Mike Galbraith
2018-06-01 13:20 ` Peter Zijlstra
2018-06-01 15:09 ` Andy Lutomirski
2018-06-01 18:56 ` Rik van Riel [this message]
2018-06-04 7:25 ` Peter Zijlstra
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