2012/1/6 Tao Ma <tm@xxxxxx>: > Hi Kosaki, > On 12/30/2011 06:07 PM, KOSAKI Motohiro wrote: >>>> Because your test program is too artificial. 20sec/100000times = >>>> 200usec. And your >>>> program repeat mlock and munlock the exact same address. so, yes, if >>>> lru_add_drain_all() is removed, it become near no-op. but it's >>>> worthless comparision. >>>> none of any practical program does such strange mlock usage. >>> yes, I should say it is artificial. But mlock did cause the problem in >>> our product system and perf shows that the mlock uses the system time >>> much more than others. That's the reason we created this program to test >>> whether mlock really sucks. And we compared the result with >>> rhel5(2.6.18) which runs much much faster. >>> >>> And from the commit log you described, we can remove lru_add_drain_all >>> safely here, so why add it? At least removing it makes mlock much faster >>> compared to the vanilla kernel. >> >> If we remove it, we lose to a test way of mlock. "Memlocked" field of >> /proc/meminfo >> show inaccurate number very easily. So, if 200usec is no avoidable, >> I'll ack you. >> But I'm not convinced yet. > Do you find something new for this? No. Or more exactly, 200usec is my calculation mistake. your program call mlock 3 times per each iteration. so, correct cost is 66usec. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>