Messages in this thread | | | Date | Wed, 12 Mar 2008 12:04:36 +0300 | From | Pavel Emelyanov <> | Subject | Re: [PATCH] Add the max_usage member on the res_counter |
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Andrew Morton wrote: > On Tue, 11 Mar 2008 17:55:46 +0300 Pavel Emelyanov <xemul@openvz.org> wrote: > >> This field is the maximal value of the usage one since the counter >> creation (or since the latest reset). >> >> To reset this to the usage value simply write anything to the >> appropriate cgroup file. > > What is the justification for making this change? Why do we need it?
The max_usage value is useful when gathering a statistical information about the particular group, as it shows the actual memory requirements for a particular group, not just some usage snapshot.
E.g. this value can be used to quickly tune the group. OpenVZ users often set the limits to maximal values and either load the container with a common patterns or leave one for a while. After this the max_usage value shows the amount of memory the container would require during its common activity. Setting the limit a bit above this value gives a pretty good configuration, that works in the most cases.
But, please see my second comment.
> Please provide this information for all patches where it is not obvious. > >> { >> + .name = "max_usage_in_bytes", >> + .private = RES_MAX_USAGE, >> + .write = mem_cgroup_max_reset, >> + .read_u64 = mem_cgroup_read, >> + }, > > Documentation/controllers/memory.txt needs updating. >
I'm preparing the Documentation/controllers/resource_counter.txt file that will describe this abstraction. Since this one can be used for many other resources (swap, kernel memory, networking, etc) this will also eliminate all the possible future duplications in the appropriate docs.
The above explanation of the max_usage attribute will be included in this doc. Should it still be included in the previous patch's comment or in the patch _as_a_ comment?
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