On Mon, Sep 18, 2017 at 03:34:47PM +0800, Aaron Lu wrote: > On Sun, Sep 17, 2017 at 07:16:15PM +0300, Tariq Toukan wrote: > > > > It's nice to have the option to dynamically play with the parameter. > > But maybe we should also think of changing the default fraction guaranteed > > to the PCP, so that unaware admins of networking servers would also benefit. > > I collected some performance data with will-it-scale/page_fault1 process > mode on different machines with different pcp->batch sizes, starting > from the default 31(calculated by zone_batchsize(), 31 is the standard > value for any zone that has more than 1/2MiB memory), then incremented > by 31 upwards till 527. PCP's upper limit is 6*batch. > > An image is plotted and attached: batch_full.png(full here means the > number of process started equals to CPU number). To be clear: X-axis is the value of batch size(31, 62, 93, ..., 527), Y-axis is the value of per_process_ops, generated by will-it-scale, higher is better. > > From the image: > - For EX machines, they all see throughput increase with increased batch > size and peaked at around batch_size=310, then fall; > - For EP machines, Haswell-EP and Broadwell-EP also see throughput > increase with increased batch size and peaked at batch_size=279, then > fall, batch_size=310 also delivers pretty good result. Skylake-EP is > quite different in that it doesn't see any obvious throughput increase > after batch_size=93, though the trend is still increasing, but in a very > small way and finally peaked at batch_size=403, then fall. > Ivybridge EP behaves much like desktop ones. > - For Desktop machines, they do not see any obvious changes with > increased batch_size. > > So the default batch size(31) doesn't deliver good enough result, we > probbaly should change the default value. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
