[lxc-users] page cache memory accounting

Mohan G mohan_gg at yahoo.com
Mon Jan 19 10:47:36 UTC 2015


As the cgroup is now say 400M and i create/write a file of 8G. My point was due to 400M limit in my group, the write should create a lot of memory pressure and there  by start the pager/shrinker activity desperately and slow down the entire write throughput. ( file does get created but performance should be far worse that without running with cgroups.) is't it ?
 

     On Monday, January 19, 2015 3:52 PM, Holger Amann <holger at sauspiel.de> wrote:
   

 Why shouldn’t it be possible to create a file with size > $some_cgroup_page_cache_memory_limit? What’s the point here?

> Am 16.01.2015 um 20:32 schrieb Serge Hallyn <serge.hallyn at ubuntu.com>:
> 
> Yes, I believe you need to use the kmem limits for that.  Those are afaik
> not yet fully supported, sadly, but my ubuntu utopic host at least has
> them available:  memory.kmem.limit_in_bytes etc
> 
> Quoting Mohan G (mohan_gg at yahoo.com):
>> Hi,I created a cgroup and set memory limit as 400M. And i ran my test program which is under this group to create a file of size 8G. ( thinking that the amount of page cache pages needed at any point of time can exceed 400M). But i did not have any issues and the file got created. So my question is do these memory limits only apply to non file based operations. ie (page cache is not accounted for ?). The question is relevant to containers too.. ( same logic applies here too).
>> RegardsMohan
>> 
> 
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