linux-kernel - Re: devpts mounts too slowly

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Message-ID: <4A301CCD.7070707@zytor.com>
Date:	Wed, 10 Jun 2009 13:51:25 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Ray Lee <ray-lk@...rabbit.org>, renton@...ton.name,
	linux-kernel@...r.kernel.org,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: devpts mounts too slowly

Andrew Morton wrote:
> 
> hm, OK.
> 
> I've now mounted 15000 devpts's and still no slowdown is evident.

I ran my test script, mounting ramfs, with n=100000, and well, gave up
since it hadn't gotten any further than 57000 or so overnight.  At that
time each individual mount was taking several seconds.

Graphing the delays seem to indicate O(n^2) behavior.

umounts do not appear affected; each umount still take negible time.

	-hpa

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