Date: Mon, 18 Jan 1999 23:09:48 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Archie Cobbs <archie@whistle.com> Cc: hackers@FreeBSD.ORG Subject: Re: Found problem w/ Paging performance over NFS Message-ID: <199901190709.XAA90152@apollo.backplane.com> References: <199901190656.WAA09547@bubba.whistle.com>
next in thread | previous in thread | raw e-mail | index | archive | help
:Matthew Dillon writes:
:> Ok. I just figured out the interaction -- in fact, we *can't* test m->busy
:> in this section of code because of the following sequence:
:>
:> vm_fault -> vnode_pager_getpages -> ffs_getpages -> ffs_read ->
:> cluster_read -> getblk -> allocbuf ( lockup )
:>
:> ffs_getpages converts the PG_BUSY into a vm_page_t->busy before getting into
:> the cluster stuff, and thus allocbuf() deep down cannot sleep on
:> vm_page_t->busy.
:>
:...
:Yow. I don't think it's possible to overcomment the VM subsystem.. :-)
:
:-Archie
Heh. Believe you me, I'm commenting everything that takes me more then
5 minutes to puzzle out, and then some!
This stuff is starting to look pretty good, I'll open the patchset up
to anyone who is interested in testing it. You can pop it off my site.
WARNING! Make backups of your original files or be prepared to re-check
them out fresh from the cvs tree. This is highly experimental code.
(for latest)
http://www.backplane.com/FreeBSD/
(last snapshot, fresh at posting time)
http://www.backplane.com/FreeBSD/dillon-swapper-A15.tgz
http://www.backplane.com/FreeBSD/FreeBSDVMWork.html
I've been testing the stuff on a 48MB diskless workstation. I've
successfully run a -j14 buildworld and it's running a -j18 right now.
If that works, I'll try a -j30 next. It's actually kinda hard to get
it to grind on a 100BaseTX LAN with the NFS paging fixes in place :-)
BTW, the patch set also includes Luoqi's NFS fix.
-Matt
Matthew Dillon
<dillon@backplane.com>
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?199901190709.XAA90152>