Hi, On Fri, 2010-04-16 at 01:51 +0900, Minchan Kim wrote: [snip] > Thanks for the explanation. It seems to be real issue. > > I tested to see effect with flush during rb tree search. > > Before I applied your patch, the time is 50300661 us. > After your patch, 11569357 us. > After my debug patch, 6104875 us. > > I tested it as changing threshold value. > > threshold time > 1000 13892809 > 500 9062110 > 200 6714172 > 100 6104875 > 50 6758316 > My results show: threshold time 100000 139309948 1000 13555878 500 10069801 200 7813667 100 18523172 50 18546256 > And perf shows smp_call_function is very low percentage. > > In my cases, 100 is best. > Looks like 200 for me. I think you meant to use the non _minmax version of proc_dointvec too? Although it doesn't make any difference for this basic test. The original reporter also has 8 cpu cores I've discovered. In his case divided by 4 cpus where as mine are divided by 2 cpus, but I think that makes no real difference in this case. I'll try and get some further test results ready shortly. Many thanks for all your efforts in tracking this down, Steve. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>