Messages in this thread | | | Date | Wed, 31 Mar 2004 16:27:32 -0500 | From | Jeff Garzik <> | Subject | Re: [PATCH] barrier patch set |
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Stephen C. Tweedie wrote: > Hi, > > On Tue, 2004-03-30 at 23:21, Jeff Garzik wrote: > > >>For IDE, O_DIRECT and O_SYNC can use special "FUA" commands, which don't >>return until the data is on the platter. > > > fsync() is still really nasty, because that can require that we wait on > IO that was submitted by the VM before we knew that there was a > synchronous IO wait coming. SCSI also has an FUA bit that can make a > difference if you've got writeback caching enabled. (And FUA on read > can bypass drive writethrough caches, too, for media verification.)
Agreed, but I did not mention fsync(), since that would not be appropriate to FUA like O_DIRECT or O_SYNC might be.
Jeff
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