From: Jakub Jelinek <jakub@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@muc.de>, Andrew Morton <akpm@digeo.com>,
Linus Torvalds <torvalds@transmeta.com>,
linux-kernel@vger.kernel.org
Subject: Re: [patch] mmap-speedup-2.5.42-C3
Date: Wed, 16 Oct 2002 04:07:54 -0400 [thread overview]
Message-ID: <20021016040754.C5659@devserv.devel.redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0210160957150.4018-100000@localhost.localdomain>; from mingo@elte.hu on Wed, Oct 16, 2002 at 10:03:52AM +0200
On Wed, Oct 16, 2002 at 10:03:52AM +0200, Ingo Molnar wrote:
>
> On 15 Oct 2002, Andi Kleen wrote:
>
> > When you oprofile KDE startup you notice that a lot of time is spent in
> > get_unmapped_area too. The reason is that every KDE process links with
> > 10-20 libraries and ends up with a 40-50 entry /proc/<pid>/maps.
>
> actually, library mappings alone should not cause a slowdown, since we
> start the search at MAP_UNMAPPED_BASE and most library mappings are below
> 1GB. But if those libraries use mmap()-ed anonymous RAM that has different
> protections then the anonymous areas do not get merged and the scanning
> overhead goes up.
Libraries mapped by dynamic linker are mapped without MAP_FIXED and unless
you use prelinking, with 0 virtual address, ie. they all end up above 1GB.
And 99% of libraries uses different protections, for the read-only and
read-write segment.
Jakub
next prev parent reply other threads:[~2002-10-16 8:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-15 13:11 [patch] mmap-speedup-2.5.42-C3 Ingo Molnar
2002-10-15 18:09 ` Andrew Morton
2002-10-15 21:30 ` Andi Kleen
2002-10-16 8:03 ` Ingo Molnar
2002-10-16 8:07 ` Jakub Jelinek [this message]
2002-10-16 8:27 ` Ingo Molnar
2002-10-16 8:22 ` Jakub Jelinek
2002-10-16 9:16 ` Andi Kleen
2002-10-16 9:47 ` Ingo Molnar
2002-10-16 12:08 ` Jakub Jelinek
2002-10-16 1:14 ` Saurabh Desai
2002-10-16 8:14 ` Ingo Molnar
2002-10-16 14:52 ` Linus Torvalds
2002-10-16 15:49 ` Arjan van de Ven
2002-10-16 16:10 ` Andrew Morton
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