Am 03.05.2011 16:54, schrieb Daniel J Blueman: Hi,
>>> The file the defrag ioctl works is that it schedules things for defrag >>> but doesn't force out the IO immediately unless you use -f. >>> >>> So, to test the result of the defrag, you need to either wait a bit or >>> run sync. >> >> Did so, no change. See my reply to cwillu for the data. > > Can you try with the compression option enabled? Eg: > > # filefrag foo.dat > foo.dat: 11 extents found > > # find . -xdev -type f -print0 | xargs -0 btrfs filesystem defragment -c > > # filefrag foo.dat > foo.dat: 1 extent found > > Seems to work fine on 2.6.39-rc5; I mounted with '-o > compress,clear_cache' though. Maybe I was expecting too much. I tried it on a file with 72 extends and was expecting for the count to go down to 1 (or very very few). This does not seem to happen with this particular file. I just tested another file (with 193 extends) and it was reduced to 5. defrag with -f, but without -c. Still mounted with compress=lzo. However, the 72 frags file is not getting any better, no matter which flags I tried. No big problem at the moment, I've found an older (Ubuntu Maverick) based system with a rotating disk that had like 50000 extends for a single file. I expect defragging that will increase performance quite nicely :-) Bernhard -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
