On Sat, Jul 02 2005, Matthias Andree wrote: > Jens Axboe <axboe@xxxxxxx> writes: > > >> I'm not acquainted with kernel/block I/O queueing internals. > > > > SCSI without TCQ or with TCQ depth=1 should be safe, provided the driver > > never reorders a command once it has received it. > > Wouldn't we rather use *deep* TCQ and set write cache enable to 0 then? Depends, if you can't use ordered tags it wont help you. > Does anybody have benchmarks with TCQ depth = 1/WCE = 1 vs. TCQ = <deep> > (64+)/WCE = 0? I only have ancient SCSI drives in test machines, so my > testing wouldn't be representative. I posted some for NCQ, see lkml/linux-ide. > >> > > 2. for traditional IDE (such as VIA 82*, PIIX_*)? > >> > > >> > In SUSE kernels, for many years. Since 2.6.7/8'ish in Linus' kernels. > >> > >> I don't care for vendor kernels. Is listing 2.6.8 safe? > > > > Check the changelogs, I can't remember exactly if it was 2.6.7 or 2.6.8 > > (or perhaps .6...). > > Hm. Any buzz^Wkeywords to look for? "barrier" doesn't seem to be the > right word, it yields only memory barriers and an as-iosched fix in > 2.6.7. I checked ChangeLog-2.6.[56789]. Grep for blk_queue_ordered or similar in the patch. -- Jens Axboe - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
