On Wed, Nov 17, 2010 at 05:59:00PM -0800, Andrew Morton wrote: > On Thu, 18 Nov 2010 12:40:51 +1100 Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > Yeah, sorry, should have posted them - I didn't because I snapped > > the numbers before the run had finished. Without series: > > > > 373.19user 14940.49system 41:42.17elapsed 612%CPU (0avgtext+0avgdata 82560maxresident)k > > 0inputs+0outputs (403major+2599763minor)pagefaults 0swaps > > > > With your series: > > > > 359.64user 5559.32system 40:53.23elapsed 241%CPU (0avgtext+0avgdata 82496maxresident)k > > 0inputs+0outputs (312major+2598798minor)pagefaults 0swaps > > > > So the wall time with your series is lower, and system CPU time is > > way down (as I've already noted) for this workload on XFS. > > How much of that benefit is an accounting artifact, moving work away > from the calling process's CPU and into kernel threads? As I spelled out in my original results, the sustained CPU usage for the unmodified kernel is ~780% - 620% fs_mark, 80% bdi-flusher, 80% kswapd (i.e. completely CPU bound on the 8p test VM). With this series, the sustained CPU usage is about 380% - 250% fs_mark, 80% bdi-flusher, 50% kswapd. IOWs, this series _halved_ the total sustained CPU usage even after taking into account all the kernel threads. With wall time also being reduced and the number of IOs issued dropping by 25%, I find it hard to classify the result as anything other than spectacular... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>