Messages in this thread | | | Subject | Re: Linux 2.6.29 | From | James Bottomley <> | Date | Wed, 25 Mar 2009 21:22:50 +0000 |
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On Wed, 2009-03-25 at 16:25 -0400, Ric Wheeler wrote: > Jeff Garzik wrote: > > Ric Wheeler wrote:> And, as I am sure that you do know, to add insult > > to injury, FLUSH_CACHE > >> is per device (not file system). > >> > >> When you issue an fsync() on a disk with multiple partitions, you > >> will flush the data for all of its partitions from the write cache.... > > > > SCSI'S SYNCHRONIZE CACHE command already accepts an (LBA, length) > > pair. We could make use of that. > > > > And I bet we could convince T13 to add FLUSH CACHE RANGE, if we could > > demonstrate clear benefit. > > > > Jeff > > How well supported is this in SCSI? Can we try it out with a commodity > SAS drive?
What do you mean by well supported? The way the SCSI standard is written, a device can do a complete cache flush when a range flush is requested and still be fully standards compliant. There's no easy way to tell if it does a complete cache flush every time other than by taking the firmware apart (or asking the manufacturer).
James
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