Messages in this thread | | | Date | Mon, 15 Jan 2007 20:51:21 -0500 | From | Jeff Garzik <> | Subject | Re: SATA exceptions with 2.6.20-rc5 |
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Jens Axboe wrote: > On Mon, Jan 15 2007, Jeff Garzik wrote: >> Jens Axboe wrote: >>> I'd be surprised if the device would not obey the 7 second timeout rule >>> that seems to be set in stone and not allow more dirty in-drive cache >>> than it could flush out in approximately that time. >> AFAIK Windows flush-cache timeout is 30 seconds, not 7 as with other >> commands... > > Ok, 7 seconds for FLUSH_CACHE would have been nice for us too though, as > it would pretty much guarentee lower latencies for random writes and > write back caching. The concern is the barrier code, of course. I guess > I should do some timings on potential worst case patterns some day. Alan > may have done that sometime in the past, iirc.
FWIW: According to the drive guys (Eric M, among others), FLUSH CACHE will "probably" be under 30 seconds, but pathological cases might even extend beyond that.
Definitely more than 7 seconds in less-than-pathological cases, unfortunately...
The SCSI layer /should/ already take this (30 second timeout) into account, for SYNCHRONIZE CACHE (and thus FLUSH CACHE for libata) but I'm too slack to check at the moment.
Jeff
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