Date: Fri, 23 Jun 2000 00:13:27 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Peter Jeremy <peter.jeremy@alcatel.com.au> Cc: Chris Dillon <cdillon@wolves.k12.mo.us>, cvs-all@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: cvs commit: src/sys/contrib/softupdates softdep.h ffs_softdep.c Message-ID: <1489.961712007@critter.freebsd.dk> In-Reply-To: Your message of "Fri, 23 Jun 2000 07:52:44 %2B1000." <00Jun23.075254est.115312@border.alcanet.com.au>
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In message <00Jun23.075254est.115312@border.alcanet.com.au>, Peter Jeremy write s: >Whilst the solution to this appears obvious (if you can't allocate a >block, but there are free blocks on the to-be-commited list, wait for >free space to become available), actually implementing it is quite >difficult if you want to avoid deadlocks. Kirk has previously >recommended that softupdates not be enabled on a filesystem unless it >has sufficient free space to absorb about 1 minute's writes. yup, this one is tricky, I tried to fix it by sleeping on the potential of allocating a block, but even that isn't enough, and had undesirable consequences. >A number of people have also claimed that softupdates interacts with >Vinum (particularly RAID-5) in undesirable ways. I believe that at >least some of this was a misunderstanding of the way softupdates >handles write re-ordering (or at least the write semantics that >softupdates expects). This one was a misunderstanding, in fact vinum/raid5 works more reliably with softupdates than without I belive. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD coreteam member | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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