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Jens Axboe schrieb am 2004-03-18: > > All these ATA fsync() vs. write cache issues have been open for much too > > long - no reproaches, but it's a pity we haven't been able to have data > > consistency for data bases and fast bulk writes (that need the write > > cache without TCQ) in the same drive for so long. I have seen Linux > > introduce TCQ for PATA early in 2.5, then drop it again. Similarly, > > FreeBSD ventured into TCQ for ATA but appears to have dropped it again > > as well. > > That's because PATA TCQ sucks :-) True. Few drives support it, and many of these you would not want to run in production... > > May I ask that the information whether a particular driver (file system, > > hardware) supports write barriers be exposed in a standard way, for > > instance in the Kconfig help lines? > > Since reiser is the first implementation of it, it gets to chose how > this works. Currently that's done by giving -o barrier=flush (=ordered > used to exist as well, it will probably return - right now we just > played with IDE). This looks as though this was not the default and required the user to know what he's doing. Would it be possible to choose a sane default (like flush for ATA or ordered for SCSI when the underlying driver supports ordered tags) and leave the user just the chance to override this? > Only PATA core needs to support it, not the chipset drivers. md and dm Hum, I know the older Promise chips were blacklisted for PATA TCQ in FreeBSD. Might "ordered" cause situations where similar things happen to Linux? How about SCSI/libata? Is the situation the same there? > aren't a difficult to implement now that unplug/congestion already > iterates the device list and I added a blkdev_issue_flush() command. So this would - for SCSI - be an sd issue rather than a driver issue as well? -- Matthias Andree Encrypt your mail: my GnuPG key ID is 0x052E7D95 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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