On Fri 07-08-15 12:38:54, Pintu Kumar wrote: > This patch add new counter slowpath_entered in /proc/vmstat to > track how many times the system entered into slowpath after > first allocation attempt is failed. This is too lowlevel to be exported in the regular user visible interface IMO. > This is useful to know the rate of allocation success within > the slowpath. What would be that information good for? Is a regular administrator expected to consume this value or this is aimed more to kernel developers? If the later then I think a trace point sounds like a better interface. > This patch is tested on ARM with 512MB RAM. > A sample output is shown below after successful boot-up: > shell> cat /proc/vmstat > nr_free_pages 4712 > pgalloc_normal 1319432 > pgalloc_movable 0 > pageoutrun 379 > allocstall 0 > slowpath_entered 585 > compact_stall 0 > compact_fail 0 > compact_success 0 > > >From the above output we can see that the system entered > slowpath 585 times. > But the existing counter kswapd(pageoutrun), direct_reclaim(allocstall), > direct_compact(compact_stall) does not tell this value. > >From the above value, it clearly indicates that the system have > entered slowpath 585 times. Out of which 379 times allocation passed > through kswapd, without performing direct reclaim/compaction. > That means the remaining 206 times the allocation would have succeeded > using the alloc_pages_high_priority. > > Signed-off-by: Pintu Kumar <pintu.k@xxxxxxxxxxx> -- Michal Hocko SUSE Labs -- 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>