linux-kernel - Re: [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushes to use function calls [POST 2]

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Message-ID: <20080819114404.GA5354@elte.hu>
Date:	Tue, 19 Aug 2008 13:44:04 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Nick Piggin <nickpiggin@...oo.com.au>
Cc:	Jeremy Fitzhardinge <jeremy@...p.org>,
	LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
	Andi Kleen <andi@...stfloor.org>,
	Jens Axboe <jens.axboe@...cle.com>
Subject: Re: [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushes
	to use function calls [POST 2]


* Nick Piggin <nickpiggin@...oo.com.au> wrote:

> On Tuesday 19 August 2008 20:20, Ingo Molnar wrote:
> > * Nick Piggin <nickpiggin@...oo.com.au> wrote:
> > > I'm especially sore about mmap because I have a customer with a
> > > database that uses a lot of mmap/munmap and those calls have slowed
> > > down something like 50%(!!) from 2.6.early to 2.6.late.
> >
> > oh, agreed that it all needs to speed up - please send testcases ...
> 
> I'm not sure if I can send the testcase I have. But this issue is 
> coming to the top of my list to investigate in mainline, so I'll check 
> out how we're doing here soon.

obviously having a repeatable testcase would jump-start any efforts to 
fix this. It doesnt have to be complex - just a .c thing kernel 
developers can run and get some quick number out of. A 50% regression 
shouldnt be too hard to reproduce even with a vastly simplified 
workload.

	Ingo
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