Hi Kame, On Wed, Apr 27, 2011 at 10:50 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > On Tue, 26 Apr 2011 13:59:34 -0700 > Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > >> What about simply removing the nr_saved_scan logic and permitting small >> scans? ÂThat simplifies the code and I bet it makes no measurable >> performance difference. >> > > ok, v2 here. How this looks ? > For memcg, I think I should add select_victim_node() for direct reclaim, > then, we'll be tune big memcg using small memory on a zone case. > > == > At memory reclaim, we determine the number of pages to be scanned > per zone as > Â Â Â Â(anon + file) >> priority. > Assume > Â Â Â Âscan = (anon + file) >> priority. > > If scan < SWAP_CLUSTER_MAX, the scan will be skipped for this time > and priority gets higher. This has some problems. > > Â1. This increases priority as 1 without any scan. > Â Â To do scan in this priority, amount of pages should be larger than 512M. > Â Â If pages>>priority < SWAP_CLUSTER_MAX, it's recorded and scan will be > Â Â batched, later. (But we lose 1 priority.) Nice catch! It looks to be much enhance. > Â Â But if the amount of pages is smaller than 16M, no scan at priority==0 > Â Â forever. Before reviewing the code, I have a question about this. Now, in case of (priority = 0), we don't do shift operation with priority. So nr_saved_scan would be the number of lru list pages. ie, 16M. Why no-scan happens in case of (priority == 0 and 16M lru pages)? What am I missing now? > > Â2. If zone->all_unreclaimabe==true, it's scanned only when priority==0. > Â Â So, x86's ZONE_DMA will never be recoverred until the user of pages > Â Â frees memory by itself. > > Â3. With memcg, the limit of memory can be small. When using small memcg, > Â Â it gets priority < DEF_PRIORITY-2 very easily and need to call > Â Â wait_iff_congested(). > Â Â For doing scan before priorty=9, 64MB of memory should be used. It makes sense. -- Kind regards, Minchan Kim -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href