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Date:      Tue, 27 Jan 2004 17:37:05 +0100
From:      des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=)
To:        Mike Silbersack <silby@silby.com>
Cc:        current@freebsd.org
Subject:   Re: 'kern.maxpipekva exceeded' messages...
Message-ID:  <xzpr7xl8i1a.fsf@dwp.des.no>
In-Reply-To: <20040127101910.P4636@odysseus.silby.com> (Mike Silbersack's message of "Tue, 27 Jan 2004 10:24:44 -0600 (CST)")
References:  <20040119233546.S39477@odysseus.silby.com> <xzpznc9tzgz.fsf@dwp.des.no> <20040127101910.P4636@odysseus.silby.com>

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Mike Silbersack <silby@silby.com> writes:
> I do not believe that there is a leak.  What actually happened is
> that between 5.1 and 5.2 I added pipe memory limits, which had not
> been present before.

Oh!  I wasn't aware that the limit did not already exist.

> 1.  Pipes overallocate memory greatly; I could probably reduce the
> memory usage of an idle pipe by 8x or so.

My problem is not idle pipes; my problem is that the following system

# sysctl kern.ipc.maxpipekva
kern.ipc.maxpipekva: 8704000
# sysctl kern.ipc.pipekva
kern.ipc.pipekva: 393216

runs out of pipe kva every monday morning when it tries to pipe a
level 0 dump through ssh.

Is there some way to impose a limit on the memory consumed by a single
pipe?  I don't care if dump blocks waiting for ssh to push out the
data, but I do care about the system crashing shortly after running
out of pipe kva.

Another problem I have is with a system that runs out of pipe kva when
I create a large number of jails.  I really need a way to find out
where all that memory goes...

> If you're interested in working on this right now, I can send you what I
> had planned to do for #1, it would be a very small amount of code,
> although it would require a bit of testing to ensure that it does not
> degrade the performance of pipes by a noticeable amount.

That would be nice.  I have several systems I can test it on.

DES
--=20
Dag-Erling Sm=F8rgrav - des@des.no



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