On 6/26/12 3:57 PM, Eric Sandeen wrote: > On 6/26/12 3:30 PM, Ric Wheeler wrote: > >> Thanks! Eric is also running some tests to evaluate the impact of various techniques :) >> >> ric > > Yup forgive me for interjecting actual numbers into the discussion ;) > > I tried running this fio recipe on v3.3, which I think does a decent job of > emulating the situation (fallocate 1G, do random 1M writes into it, with > fsyncs after each): > > [test] > filename=testfile > rw=randwrite > size=1g > filesize=1g > bs=1024k > ioengine=sync > fallocate=1 > fsync=1 > > Stock ext4 (3 tests w/ file remove & cache drop in between): > > WRITE: io=1024.0MB, aggrb=16322KB/s, minb=16713KB/s, maxb=16713KB/s, mint=64243msec, maxt=64243msec > WRITE: io=1024.0MB, aggrb=16249KB/s, minb=16639KB/s, maxb=16639KB/s, mint=64528msec, maxt=64528msec > WRITE: io=1024.0MB, aggrb=16370KB/s, minb=16763KB/s, maxb=16763KB/s, mint=64052msec, maxt=64052msec And as a sanity check, here are the rates for overwriting existing, written blocks in the file: WRITE: io=1024.0MB, aggrb=17778KB/s, minb=18205KB/s, maxb=18205KB/s, mint=58980msec, maxt=58980msec WRITE: io=1024.0MB, aggrb=17825KB/s, minb=18252KB/s, maxb=18252KB/s, mint=58826msec, maxt=58826msec WRITE: io=1024.0MB, aggrb=17769KB/s, minb=18195KB/s, maxb=18195KB/s, mint=59010msec, maxt=59010msec so this does look like about ~10% overhead for converting the extents. > With the patch which exposes other users' data: > > WRITE: io=1024.0MB, aggrb=17840KB/s, minb=18268KB/s, maxb=18268KB/s, mint=58776msec, maxt=58776msec > WRITE: io=1024.0MB, aggrb=17841KB/s, minb=18269KB/s, maxb=18269KB/s, mint=58773msec, maxt=58773msec > WRITE: io=1024.0MB, aggrb=17828KB/s, minb=18255KB/s, maxb=18255KB/s, mint=58816msec, maxt=58816msec overwrites: WRITE: io=1024.0MB, aggrb=17768KB/s, minb=18194KB/s, maxb=18194KB/s, mint=59014msec, maxt=59014msec WRITE: io=1024.0MB, aggrb=17855KB/s, minb=18283KB/s, maxb=18283KB/s, mint=58726msec, maxt=58726msec WRITE: io=1024.0MB, aggrb=17838KB/s, minb=18266KB/s, maxb=18266KB/s, mint=58783msec, maxt=58783msec As expected, overwriting stale data is no slower than overwriting file data. > so about 10% faster than without. > > XFS, FWIW: > > WRITE: io=1024.0MB, aggrb=24008KB/s, minb=24584KB/s, maxb=24584KB/s, mint=43675msec, maxt=43675msec > WRITE: io=1024.0MB, aggrb=24069KB/s, minb=24647KB/s, maxb=24647KB/s, mint=43564msec, maxt=43564msec > WRITE: io=1024.0MB, aggrb=24054KB/s, minb=24632KB/s, maxb=24632KB/s, mint=43591msec, maxt=43591msec overwrites: WRITE: io=1024.0MB, aggrb=24108KB/s, minb=24687KB/s, maxb=24687KB/s, mint=43494msec, maxt=43494msec WRITE: io=1024.0MB, aggrb=24129KB/s, minb=24708KB/s, maxb=24708KB/s, mint=43456msec, maxt=43456msec WRITE: io=1024.0MB, aggrb=24164KB/s, minb=24744KB/s, maxb=24744KB/s, mint=43393msec, maxt=43393msec looks like negligible overhead for the conversions here, < 1%. -Eric > which is 35% faster than ext4 with the risky patch. > > Haven't yet tried overwrites or done any tracing or profiling, but I think the fio recipe is a decent demonstrator, I'll try the overwrites etc in a bit when I get a moment. > > -Eric > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" 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-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
