Messages in this thread | | | Date | Wed, 18 Jan 2006 17:25:44 +0100 | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: io performance... |
| |
On 1/18/06, Phillip Susi <psusi@cfl.rr.com> wrote: > I was going to say, doesn't the kernel set the FUA bit on the write > request to push important flushes through the disk's write-back cache? > Like for filesystem journal flushes?
Yes if: * you have a disk supporting FUA * you have kernel >= 2.6.16-rc1 * you are using SCSI (this includes libata) driver [ support for IDE driver will be merged later when races in changing IDE settings are fixed ]
Bartlomiej
> Alan Cox wrote: > > Not always. If you have a cache flush command and the OS knows about > > using it, or if you don't care if the data gets lost over a power > > failure (eg /tmp and swap) it makes sense to force it. > > > > The raid controller drivers that fake scsi don't always fake enough of > > scsi to report that they support cache flushes and the like. That > > doesn't mean the controller itself is neccessarily doing one thing or > > the other. - 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/
| |