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: <20080819103100.GH9807@one.firstfloor.org>
Date:	Tue, 19 Aug 2008 12:31:00 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Nick Piggin <nickpiggin@...oo.com.au>
Cc:	Ingo Molnar <mingo@...e.hu>, 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]

> 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.

These are small mmaps right? Also in this case no kmalloc should
be needed anyways.

AFAIK mmap flushing hasn't changed much in 2.6 and it tends
to batch well anyways in this case (unlike vmscan swapping). I would be 
careful to really optimize the real culprits which are likely elsewhere.

-Andi
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