Date: Wed, 2 Oct 1996 23:17:03 +0900 (KST) From: Heo Sung-Gwan <heo@cslsun10.sogang.ac.kr> To: freebsd-hackers@FreeBSD.ORG Cc: freebsd-fs@FreeBSD.ORG Subject: vnode and cluster read-ahead Message-ID: <Pine.SUN.3.93.961002231449.5132A-100000@cslsun10>
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When a file is open serveral times simultaneously cluster read-ahead
buffer cache using vnode seem to have some problems.
As a process A reads a file F *sequentially* the fields(v_maxra, v_ralen, etc) of the vnode of F increases. As a result read-ahead of next cluster happens.
But when a process B opens F and reads it the values of the fields are
changed. So the process A's read-ahead is disturbed whenever process B is
rescheduled.
I think the fields for read-ahead must be in struct file rather than vnode.
There exists one vnode for a file but a file may be open serveral times.
What's your opinion, hackers?
--
Heo Sung-Gwan
Dept. of Computer Science, Sogang University, Seoul, Korea.
E-mail: heo@cslsun10.sogang.ac.kr
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