On Mon, Apr 06, 2009 at 05:01:11PM -0500, Steven Pratt wrote: > I am continuing to do runs to provide more data on the random write > issues with btrfs. I have just posted 2 sets of runs here: > http://btrfs.boxacle.net/repository/raid/longrun/ > > these are on a pull of the btrfs-unstable experimental branch from 4/3. > > These are 100 minute runs of the 128 thread random write workload on the > raid system (1 for btrfs and 1 for ext3). Included in these runs are > graphs of all the iostat, sar and mpstat data (see analysis directories). > > A couple of interesting things. First, we see the choppiness of the IO > in btrfs compared to ext3. > http://btrfs.boxacle.net/repository/raid/longrun/btrfs-longrun/btrfs1.ffsb.random_writes__threads_0128.09-04-06_10.25.03/analysis/iostat-processed.001/chart.html > > > http://btrfs.boxacle.net/repository/raid/longrun/ext3-longrun/btrfs1.ffsb.random_writes__threads_0128.09-04-06_13.44.49/analysis/iostat-processed.001/chart.html > > > > In particular look at graphs 7 and 11 which show write iops and > throughput. Ext3 is nice and smooth, while btrfs has a repeating > pattern of dips and spikes, with IO going to 0 on a regular basis. > > Another interesting observation is what looks a lot like a memory leak. > Looking at chart 6 Memory at : > http://btrfs.boxacle.net/repository/raid/longrun/btrfs-longrun/btrfs1.ffsb.random_writes__threads_0128.09-04-06_10.25.03/analysis/sar-processed.001/chart.html > > > we see that the amount of page cache drops slowly throughout the entire > run. Starting up around 3.5GB and dropping to about 2.3GB by the end of > the run. The memory seems to have moved to the slab which grew to > 1.5GB. Doing a repeat of the run while watching slabtop, we see that > size-2048 is responsible for the majority of the slab usage (over 1GB). > > We do not see this behavior under ext3. Yeah, which tree are you running against? I had this problem a few weeks ago, but I don't remember if it was fixed or anything usefull like that, it may be worth it to try running against the newest stuff. Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
