Date: Mon, 18 Jan 1999 22:56:29 -0800 (PST) From: Archie Cobbs <archie@whistle.com> To: dillon@apollo.backplane.com (Matthew Dillon) Cc: hackers@FreeBSD.ORG Subject: Re: Found problem w/ Paging performance over NFS Message-ID: <199901190656.WAA09547@bubba.whistle.com> In-Reply-To: <199901190128.RAA84794@apollo.backplane.com> from Matthew Dillon at "Jan 18, 99 05:28:35 pm"
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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. > > Ick. I'm going to add a comment explaining that case. Yow. I don't think it's possible to overcomment the VM subsystem.. :-) -Archie ___________________________________________________________________________ Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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