On Thu, Jul 29, 2010 at 03:07:17PM -0500, James Bottomley wrote: > There's lies, damned lies and benchmarks .. but what I was thinking is > could we just do the right thing? SCSI exposes (in sd) the interfaces > to change the cache setting, so if the customer *doesn't* specify > barriers on mount, could we just flip the device to write through it > would be more performant in most use cases. We could for SCSI and ATA, but probably not easily for other kind of storage. Except that it's not that simple as we have partitions and volume managers inbetween - different filesystems sitting on the same device might have very different ideas of what they want. For SCSI we can at least permanently disable the cache, but ATA devices keep coming up again with the volatile write cache enabled after a reboot, or even worse a suspend to ram / resume cycle. The latter is what keeps me from just disabling the volatile cache on my laptop, despite that option giving significanly better performance for typical kernel developer workloads. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
