Date: Mon, 7 Aug 2000 12:51:16 -0700 (PDT) From: Yvonne Coady <ycoady@cs.ubc.ca> To: freebsd-hackers@freebsd.org Subject: ffs_getpages() Message-ID: <Pine.SOL.4.21.0008071233230.18481-100000@newcastle.cs.ubc.ca>
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Just wondering if anyone can shed some light on the changes in the page fault handling code in 3.3 vs 4.0. I've noticed that the async read ahead that used to work for mmaped files via a VOP_READ in ffs_getpages() is no longer there... I've run some very simple (and by no means exhaustive) tests, and on the surface the tradeoff appears to be that in 3.3 the disk is accessed synchronously, 16 pages at a time, whereas in 4.0 access may be asynchronous, 32 pages at a time. I am aware of the fact that in 3.3, using the vnode vlastr field was maybe not a perfect way to detect seq access for "normal" objects in ffs_getpages, but I thought the asynch read ahead was a real bonus - I might be overlooking something obvious here, but can anyone tell me why this has changed? Thanks, Yvonne To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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