Date: Thu, 12 Apr 2001 13:53:35 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Rik van Riel <riel@conectiva.com.br>, David Xu <bsddiy@21cn.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: vm balance Message-ID: <200104122053.f3CKrZ424106@earth.backplane.com> References: <59188.987108650@critter>
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:In message <200104121757.f3CHvJd20639@earth.backplane.com>, Matt Dillon writes:
:
:> Again, keep in mind that the namei cache is strictly throw-away, but
:> entries can often be reconstituted later by the filesystem without I/O
:> due to the VM Page cache (and/or buffer cache depending on
:> vfs.vmiodirenable). So as with the buffer cache and inode cache,
:> the number of entries can be limited without killing performance or
:> scaleability.
:
:Uhm, that is actually not true.
:
:We keep namecache entries around as long as we can use them, and that
:generally means that recreating them is a rather expensive operation,
:involving creation of vnode and very likely a vm object again.
The vnode cache is a different cache. positive namei hits will
reference a vnode, but namei elements can be flushed at any
time without flushing the underlying vnode.
-Matt
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