Messages in this thread | | | Date | Fri, 11 Jul 2008 16:13:49 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH][RFC] dirty balancing for cgroups |
| |
On Fri, 11 Jul 2008 14:59:26 +0900 (JST) yamamoto@valinux.co.jp (YAMAMOTO Takashi) wrote:
> > > > - This looks simple but, could you merge this into memory resource controller ? > > > > > > why? > > > > > 3 points. > > 1. Is this useful if used alone ? > > it can be. why not? > > > 2. memcg requires this kind of feature, basically. > > > > 3. I wonder I need more work to make this work well under memcg. > > i'm not sure if i understand these points. can you explain a bit? > In my understanding, dirty_ratio is for helping memory (reclaim) subsystem.
See comments in fs/page-writeback.c:: determin_dirtyable_memory() == /* * Work out the current dirty-memory clamping and background writeout * thresholds. * * The main aim here is to lower them aggressively if there is a lot of mapped * memory around. To avoid stressing page reclaim with lots of unreclaimable * pages. It is better to clamp down on writers than to start swapping, and * performing lots of scanning. * * We only allow 1/2 of the currently-unmapped memory to be dirtied. * * We don't permit the clamping level to fall below 5% - that is getting rather * excessive. * * We make sure that the background writeout level is below the adjusted * clamping level. ==
"To avoid stressing page reclaim with lots of unreclaimable pages"
Then, I think memcg should support this for helping relcaim under memcg.
> my patch penalizes heavy-writer cgroups as task_dirty_limit does > for heavy-writer tasks. i don't think that it's necessary to be > tied to the memory subsystem because i merely want to group writers. > Hmm, maybe what I need is different from this ;) Does not seem to be a help for memory reclaim under memcg.
Thanks, -Kame
| |