Message-ID: <4A526AEF.3070407@zytor.com>
Date: Mon, 06 Jul 2009 14:21:51 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Alexey Vlasov <renton@renton.name>
CC: Ray Lee <ray-lk@madrabbit.org>, Andrew Morton <akpm@linux-foundation.org>,
       linux-kernel@vger.kernel.org
Subject: Re: devpts mounts too slowly
References: <20090603142801.GC21646@beaver.vrungel.ru> <4A26EB18.6060907@zytor.com> <20090609161945.811cc01f.akpm@linux-foundation.org> <2c0942db0906091630l1cc79647h8689e9e929ed1bba@mail.gmail.com> <4A2EF833.6080300@zytor.com> <20090706195252.GA7484@beaver.vrungel.ru>
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Alexey Vlasov wrote:
> On Tue, Jun 09, 2009 at 05:02:59PM -0700, H. Peter Anvin wrote:
> 
>> A quick script seems to confirm that the time starts creeping up as the
>> number of mount points increase; on my Core i7 system the 10000th mount
>> takes around 50 ms whereas the early instances are submillisecond, and
>> the increase *seems* to be O(n log n) or thereabouts -- slightly
>> superlinear but not a good fit for a power law.
> 
> I have prepared a new machine for testing, and I don't see any slowdown
> by mounting devpts.
> Total mounts on it:
> # wc -l /proc/mounts
> 153481 /proc/mounts
> # fgrep -c devpts /proc/mounts
> 10231
> 
> On my other servers there're slowdown already by this number of:
> # wc -l /proc/mounts
> 49889 /proc/mounts
> # fgrep -c devpts /proc/mounts
> 3323
> 
> But the first box is totally empty, others are in use, may be this
> matters?
> 

Do you have /selinux mounted on one of them?

	-hpa

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