Date: Thu, 12 Apr 2001 22:55:36 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Matt Dillon <dillon@earth.backplane.com> Cc: Rik van Riel <riel@conectiva.com.br>, David Xu <bsddiy@21cn.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: vm balance Message-ID: <59487.987108936@critter> In-Reply-To: Your message of "Thu, 12 Apr 2001 13:53:35 PDT." <200104122053.f3CKrZ424106@earth.backplane.com>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <200104122053.f3CKrZ424106@earth.backplane.com>, Matt Dillon writes: > >: >: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. Right, but doing so means that to refind that vnode from the name is (comparatively) very expensive. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?59487.987108936>