Date: Wed, 22 Mar 2000 16:10:39 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Mike Smith <msmith@FreeBSD.ORG> Cc: Paul Richards <paul@originative.co.uk>, Richard Wendland <richard@netcraft.com>, Alfred Perlstein <bright@wintelcom.net>, Poul-Henning Kamp <phk@critter.freebsd.dk>, current@FreeBSD.ORG, fs@FreeBSD.ORG Subject: Re: FreeBSD random I/O performance issues Message-ID: <200003230010.QAA94351@apollo.backplane.com> References: <200003222039.MAA00661@mass.cdrom.com>
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:
:> effects of the I/O being in-progress. If a user program doesn't access
:> any of the information it recently wrote the whole mechanism winds up
:> operating asynchronously in the background. If a user program does,
:> then the write behind mechanism breaks down and you get a stall.
:
:What makes no sense is that it should be perfectly ok to _read_ this
:information back.
When we separate out the read vs write access in the buffer
cache API we *will* be able to read the information back while a
write is in progress. At the moment the buffer cache has no clue
how a buffer is going to be used, which means the buffer is locked
exclusively.
-Matt
Matthew Dillon
<dillon@backplane.com>
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