On Sep 18, 2009 07:43 -0400, Ric Wheeler wrote: > On 09/18/2009 02:09 AM, Martin K. Petersen wrote: >>>>>>> "Ric" == Ric Wheeler<rwheeler@xxxxxxxxxx> writes: >>>>>>> >> Ric> One note - the WRITE_SAME command in SCSI has long been used by >> Ric> array vendors to do relatively high performance zero fills. >> >> I've been working on WRITE SAME and UNMAP support recently (layering on >> top of Christoph's patch kit). It might be worthwhile to expose the >> WRITE SAME functionality further up the stack. It could also be helpful >> for initializing RAID disks, for instance... > > Using it to initialize RAID disks is exactly what it is there for - that > sounds quite useful... In ext4 we already have a routine ext4_ext_zeroout() that is used to zero out chunks of disk in order to wipe uninitialized extents when they need to be put into use. It currently maps ZERO_PAGE() multiple times to avoid causing cache pressure, but if we could wire it up to some block-level routine that optimized this it would be even better. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
