linux-kernel - Re: devpts mounts too slowly

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Message-ID: <20090706195252.GA7484@beaver.vrungel.ru>
Date:	Mon, 6 Jul 2009 23:52:52 +0400
From:	Alexey Vlasov <renton@...ton.name>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ray Lee <ray-lk@...rabbit.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: devpts mounts too slowly

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?

-- 
BRGDS. Alexey Vlasov.
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