Messages in this thread | | | Date | Sat, 28 Jun 2008 13:36:15 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [RFC 0/5] Memory controller soft limit introduction (v3) |
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On Fri, 27 Jun 2008 20:48:08 +0530 Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> This patchset implements the basic changes required to implement soft limits > in the memory controller. A soft limit is a variation of the currently > supported hard limit feature. A memory cgroup can exceed it's soft limit > provided there is no contention for memory. > > These patches were tested on a x86_64 box, by running a programs in parallel, > and checking their behaviour for various soft limit values. > > These patches were developed on top of 2.6.26-rc5-mm3. Comments, suggestions, > criticism are all welcome! > > A previous version of the patch can be found at > > http://kerneltrap.org/mailarchive/linux-kernel/2008/2/19/904114 > I have a couple of comments.
1. Why you add soft_limit to res_coutner ? Is there any other controller which uses soft-limit ? I'll move watermark handling to memcg from res_counter becasue it's required only by memcg.
2. *please* handle NUMA There is a fundamental difference between global VMM and memcg. global VMM - reclaim memory at memory shortage. memcg - for reclaim memory at memory limit Then, memcg wasn't required to handle place-of-memory at hitting limit. *just reducing the usage* was enough. In this set, you try to handle memory shortage handling. So, please handle NUMA, i.e. "what node do you want to reclaim memory from ?" If not, - memory placement of Apps can be terrible. - cannot work well with cpuset. (I think)
3. I think when "mem_cgroup_reclaim_on_contention" exits is unclear. plz add explanation of algorithm. It returns when some pages are reclaimed ?
4. When swap-full cgroup is on the top of heap, which tends to contain tons of memory, much amount of cpu-time will be wasted. Can we add "ignore me" flag ?
Maybe "2" is the most important to implement this. I think this feature itself is interesting, so please handle NUMA.
"4" includes the user's (middleware's) memcg handling problem. But maybe a problem should be fixed in future.
Thanks, -Kame
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