linux-kernel - Re: [PATCH v5 6/7] x86/tlb: optimizing flush_tlb

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Date:	Tue, 15 May 2012 16:04:57 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Luming Yu <luming.yu@...il.com>,
	Nick Piggin <npiggin@...il.com>, Alex Shi <alex.shi@...el.com>,
	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, arnd@...db.de,
	fweisbec@...il.com, jeremy@...p.org, riel@...hat.com, luto@....edu,
	avi@...hat.com, len.brown@...el.com, dhowells@...hat.com,
	fenghua.yu@...el.com, yinghai@...nel.org, ak@...ux.intel.com,
	cpw@....com, steiner@....com, akpm@...ux-foundation.org,
	penberg@...nel.org, hughd@...gle.com, rientjes@...gle.com,
	kosaki.motohiro@...fujitsu.com, n-horiguchi@...jp.nec.com,
	tj@...nel.org, oleg@...hat.com, axboe@...nel.dk, jmorris@...ei.org,
	kamezawa.hiroyu@...fujitsu.com, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org, yongjie.ren@...el.com,
	linux-arch@...r.kernel.org, jcm@...masters.org
Subject: Re: [PATCH v5 6/7] x86/tlb: optimizing flush_tlb_mm

On Tue, May 15, 2012 at 09:39:05AM -0400, Steven Rostedt wrote:
> > But you have to weight that against the cost of re-population, and
> > that's the difficult bit, since we have no clue how many tlb entries are
> > in use by the current cr3.
> > 
> > It might be possible for intel to give us this information, I've asked
> > for something similar for cachelines.
> 
> What information? The # of tlb entries in use?

... by the current %cr3, yes.

And also, before we delve into details, we still don't have a
representative benchmark where this shows any improvement.

-- 
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Boris.

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