Re: devpts mounts too slowly

From: H. Peter Anvin
Date: Mon Jul 06 2009 - 17:22:21 EST


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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