linux-kernel - Re: [RFC][PATCH 0/6] Another go at speculative page faults

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Message-ID: <20141023110438.GQ21513@worktop.programming.kicks-ass.net>
Date:	Thu, 23 Oct 2014 13:04:38 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	"Kirill A. Shutemov" <kirill@...temov.name>,
	Ingo Molnar <mingo@...nel.org>, torvalds@...ux-foundation.org,
	paulmck@...ux.vnet.ibm.com, tglx@...utronix.de,
	akpm@...ux-foundation.org, riel@...hat.com, mgorman@...e.de,
	oleg@...hat.com, mingo@...hat.com, minchan@...nel.org,
	kamezawa.hiroyu@...fujitsu.com, viro@...iv.linux.org.uk,
	dave@...olabs.net, linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC][PATCH 0/6] Another go at speculative page faults

On Thu, Oct 23, 2014 at 06:40:05PM +0800, Lai Jiangshan wrote:
> On 10/22/2014 01:56 AM, Peter Zijlstra wrote:
> > On Tue, Oct 21, 2014 at 08:09:48PM +0300, Kirill A. Shutemov wrote:
> >> It would be interesting to see if the patchset affects non-condended case.
> >> Like a one-threaded workload.
> > 
> > It does, and not in a good way, I'll have to look at that... :/
> 
> Maybe it is blamed to find_vma_srcu() that it doesn't take the advantage of
> the vmacache_find() and cause more cache-misses.

Its what I thought initially, I tried doing perf record with and
without, but then I ran into perf diff not quite working for me and I've
yet to find time to kick that thing into shape.

> Is it hard to use the vmacache in the find_vma_srcu()?

I've not had time to look at it.
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