On Wed, Sep 28, 2011 at 1:13 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > On Tue, 27 Sep 2011 17:49:04 -0700 > Michel Lespinasse <walken@xxxxxxxxxx> wrote: > >> Scan some number of pages from each node every second, instead of trying to >> scan the entime memory at once and being idle for the rest of the configured >> interval. >> >> In addition to spreading the CPU usage over the entire scanning interval, >> this also reduces the jitter between two consecutive scans of the same page. >> >> >> Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx> > > Does this scan thread need to be signle thread ? It tends to perform worse if we try making it multithreaded. What happens is that the scanning threads call page_referenced() a lot, and if they both try scanning pages that belong to the same file that causes the mapping's i_mmap_mutex lock to bounce. Same things happens if they try scanning pages that belong to the same anon VMA too. -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- 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>