Date: Sun, 23 Sep 2001 11:34:01 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Matt Dillon <dillon@earth.backplane.com> Cc: David Greenman <dg@root.com>, Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp>, bright@wintelcom.net, hackers@FreeBSD.ORG Subject: Re: Conclusions on... was Re: More on the cache_purgeleafdirs() routine Message-ID: <96469.1001237641@critter> In-Reply-To: Your message of "Sat, 22 Sep 2001 23:42:25 PDT." <200109230642.f8N6gPj84955@earth.backplane.com>
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In message <200109230642.f8N6gPj84955@earth.backplane.com>, Matt Dillon writes: > My patch doesn't make a distinction but assumes that (A) will tend to > hold for higher level directories: that is, that higher level directories > tend to be accessed more often and thus will tend to have pages in the > VM Page Cache, and thus not be candidates for reuse anyway. So my patch > has a very similar effect but without the overhead. Back when I rewrote the VFS namecache back in 1997 I added that clause because I saw directories getting nuked in no time because there were no pages holding on to them (device nodes were even worse!) So refresh my memory here, does directories get pages cached in VM if you have vfs.vmiodirenable=0 ? What about !UFS filesystems ? Do they show a performance difference ? Also, don't forget that if the VM system gave preferential caching to directory pages, we wouldn't need the VFS-cache very much in the first place... -- 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
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