Date: Wed, 6 May 1998 17:10:21 +1000 From: Bruce Evans <bde@zeta.org.au> To: julian@whistle.com, phk@critter.freebsd.dk Cc: bde@FreeBSD.ORG, cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, cvs-sys@FreeBSD.ORG Subject: Re: cvs commit: src/sys/kern vfs_cluster.c Message-ID: <199805060710.RAA00161@godzilla.zeta.org.au>
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>It should really be a mount-option, shouldn't it ? Sort of. Mostly not. Clustering is already a mount option, following a suggestion a few months ago by someone named phk. However, vn needs an anti-clustering flag to prevent multiple layers of clustering, and all devices need to to specify their minimum, best and maximum block sizes better. >>Talking of clusterring.. >> >>One problem with clustering is the fact that the flag that dissallows >>CLUSTERING is stored in the BDEVSW entry. >> >>from sys/conf.h: >>#define D_NOCLUSTERR 0x10000 /* disables cluter read */ >>#define D_NOCLUSTERW 0x20000 /* disables cluster write */ >>#define D_NOCLUSTERRW (D_NOCLUSTERR | D_NOCLUSTERW) >> >> which is patently the wrong place for it. for several reasons: >> >>1/ different SCSI devices may have different ideas about clustering.. Only vn needs it here, so this isn't a problem. d_maxio is a problem. >>2/ in DEVFS/SLICE, all disks come in through the same major number/devfs[] >>entry no matter which driver they eventually get passed to. DEVFS/SLICE could easily have bugs like that :-). >>3/ [bc]devsw entries will totally go away anyhow. Maybe. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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