Date: Thu, 12 Jul 2001 22:36:36 -0400 From: Leo Bicknell <bicknell@ufp.org> To: Mike Silbersack <silby@silby.com> Cc: Alfred Perlstein <bright@sneakerz.org>, Matt Dillon <dillon@earth.backplane.com>, Leo Bicknell <bicknell@ufp.org>, hackers@FreeBSD.ORG Subject: Re: Network performance tuning. Message-ID: <20010712223636.B77503@ussenterprise.ufp.org> In-Reply-To: <20010712212051.K21859-100000@achilles.silby.com>; from silby@silby.com on Thu, Jul 12, 2001 at 09:27:54PM -0500 References: <20010712211819.D6664@sneakerz.org> <20010712212051.K21859-100000@achilles.silby.com>
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On Thu, Jul 12, 2001 at 09:27:54PM -0500, Mike Silbersack wrote:
> I'd like to do this also, provided that we also change the mbuf to cluster
> ratio from 4/1 to 2/1. This will ensure that the doubled per-socket
> memory usage doesn't cause systems to run out of clusters earlier than
> before.
This is sort of backwards. Today we have (kern/uipc_mbuf.c):
#ifndef NMBCLUSTERS
#define NMBCLUSTERS (512 + MAXUSERS * 16)
#endif
TUNABLE_INT_DECL("kern.ipc.nmbclusters", NMBCLUSTERS, nmbclusters);
TUNABLE_INT_DECL("kern.ipc.nmbufs", NMBCLUSTERS * 4, nmbufs);
What you actually want to do is double the number of clusters:
#define NMBCLUSTERS (512 + MAXUSERS * 32)
And then do half as many mbuf's per cluster:
TUNABLE_INT_DECL("kern.ipc.nmbufs", NMBCLUSTERS * 2, nmbufs);
I think. Here's a sample from a system I run (netstat -m):
151/5024/18432 mbufs in use (current/peak/max):
128/4608/4608 mbuf clusters in use (current/peak/max)
As you can see, clusters peaked, while mbuf's were only 1/3 used.
I want to see some data points from other types of servers before
saying this really is a good idea. That said, so far every system
I've checked runs out of clusters before mbuf's.
Can some other people check systems in various forms of use?
--
Leo Bicknell - bicknell@ufp.org
Systems Engineer - Internetworking Engineer - CCIE 3440
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