This sounds like the bug I _think_ I just fixed - Do you suppose you could try again with the current bcache branch? On Mon, Apr 22, 2013 at 12:21 PM, Dongsu Park <dongsu.park@xxxxxxxxxxxxxxxx> wrote: > Hi, > > has anyone succeeded backporting bcache(-testing) branch to kernel 3.4? > > I tried to get it working, patching commits from bcache-testing branch > as well as block patches by Kent, on top of Kernel 3.4.23. > > * writeback mode > * backing device: MD-RAID0, or a HDD > * cache device: loopback device on tmpfs (for test) > * testing command: > dd if=/dev/zero of=/dev/bcache0 bs=4K count=1M oflag=sync > > Everything works fine, except for a problem of sync operation. > Every write request is being immediately flushed into backing device. > That's actually what I want to avoid in writeback caches. > Observing block I/Os with iostat, it's weird that no data is actually > written to backing device, despite of high IOPs. e.g.: > > Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s > avgrq-sz avgqu-sz await r_await w_await svctm %util > vdb 0.00 0.00 0.00 2550.00 0.00 0.00 > 0.00 2.05 0.81 0.00 0.81 0.26 67.00 > > If I test bcache-testing branch based on kernel 3.9-rc3, which means > without backporting, then it works well without such massive bogus syncs. > bcache-3.2 is also fine. So I suppose there might be any change on the > block layer between 3.4 and 3.9, making bcache work in such a strange way. > > Any idea? > > Dongsu > > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
