Date: Tue, 28 Dec 1999 00:13:13 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Mike Smith <msmith@FreeBSD.ORG>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern uipc_mbuf.c Message-ID: <199912280813.AAA37881@apollo.backplane.com> References: <199912280646.WAA01349@mass.cdrom.com>
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:Note that if there's a reason why mbuf/mbcluster allocation should be
:allowed to 'steal' from the others' memory pool, then this will need to
:be backed out. There's probably also room for some rate-limited
:warning messages in these checks. Suggestions always welcome.
:
:> msmith 1999/12/27 22:35:58 PST
:>
:> Modified files:
:> sys/kern uipc_mbuf.c
:> Log:
:> Actively limit the allocation of mbufs to NMBUFS/nmbufs and mbuf clusters
:> to NMBCLUSTERS/nmbclusters/kern.ipc.nmbclusters.
:>
:> Add a read-only sysctl kern.ipc.nmbufs matching kern.ipc.nmbclusters.
:>
:> Submitted by: Bosko Milekic <bmilekic@dsuper.net>
:>
:> Revision Changes Path
:> 1.51 +23 -3 src/sys/kern/uipc_mbuf.c
:
:--
:\\ Give a man a fish, and you feed him for a day. \\ Mike Smith
:\\ Tell him he should learn how to fish himself, \\ msmith@freebsd.org
:\\ and he'll hate you for a lifetime. \\ msmith@cdrom.com
Well, yes, there is: It's an issue of stability. If you run out of
either you are dead in the water so you might as well steal, yes? If
you don't do this you now have *two* hard limits instead of *one*
that will adversely effect the machine if hit. Even though the
defaults are hardwired, the packet mix depends on the use the machine
is put to. With hardwired defaults the machine is never going to be
able to fit the use perfectly.
Stealing is a way to dynamically balance the two pools. Maybe not the
best way, but better then nothing, at least while we continue to use
hard limits. Both pools operate under the same interrupt handling
restrictions so stealing is easy.
-Matt
Matthew Dillon
<dillon@backplane.com>
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