On Fri, 9 Apr 2010 13:45:53 +0900 KAMEZAWA Hiroyuki wrote:
> Documentation update.
>
> Some information are old, and I think current documentation doesn't work
> as "a guide for users".
> We need summary of all of our controls, at least.
>
> Changelog: 2010/04/09
> * replace 'lru' with 'LRU' and 'oom' with 'OOM'
> * fixed double-space breakage
> * applied all comments and fixed wrong parts pointed out.
> * fixed cgroup.procs
>
> Changelog: 2009/04/07
> * fixed tons of typos.
> * replaced "memcg" with "memory cgroup" AMAP.
> * replaced "mem+swap" with "memory+swap"
>
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> ---
> Documentation/cgroups/memory.txt | 277 ++++++++++++++++++++++++++-------------
> 1 file changed, 188 insertions(+), 89 deletions(-)
>
> Index: mmotm-temp/Documentation/cgroups/memory.txt
> ===================================================================
> --- mmotm-temp.orig/Documentation/cgroups/memory.txt
> +++ mmotm-temp/Documentation/cgroups/memory.txt
> @@ -106,14 +135,14 @@ the necessary data structures and check
> is over its limit. If it is then reclaim is invoked on the cgroup.
> More details can be found in the reclaim section of this document.
> If everything goes well, a page meta-data-structure called page_cgroup is
> -allocated and associated with the page. This routine also adds the page to
> -the per cgroup LRU.
> +updated. page_cgroup has its own LRU on cgroup.
> +(*) page_cgroup structure is allocated at boot/memory-hotplug time.
>
> 2.2.1 Accounting details
>
> All mapped anon pages (RSS) and cache pages (Page Cache) are accounted.
> -(some pages which never be reclaimable and will not be on global LRU
> - are not accounted. we just accounts pages under usual vm management.)
> +Some pages which are never reclaimable and will not be on the global LRU
> +are not accounted. We just accounts pages under usual VM management.
We just account
>
> RSS pages are accounted at page_fault unless they've already been accounted
> for earlier. A file page will be accounted for as Page Cache when it's
> @@ -248,15 +297,24 @@ caches, RSS and Active pages/Inactive pa
>
> 4. Testing
>
> -Balbir posted lmbench, AIM9, LTP and vmmstress results [10] and [11].
> -Apart from that v6 has been tested with several applications and regular
> -daily use. The controller has also been tested on the PPC64, x86_64 and
> -UML platforms.
> +For testing features and implementation, see memcg_test.txt.
> +
> +Performance test is also important. To see pure memory cgroup's overhead,
> +testing on tmpfs will give you good numbers of small overheads.
> +Example: do kernel make on tmpfs.
> +
> +Page-fault scalability is also important. At measuring parallel
> +page fault test, multi-process test may be better than multi-thread
> +test because it has noise of shared objects/status.
> +
> +But above 2 is testing extreme situation. Trying usual test under memory cgroup
I would have said:
But the above two are testing extreme situations.
> +is always helpful.
> +
>
> 4.1 Troubleshooting
>
> Sometimes a user might find that the application under a cgroup is
> -terminated. There are several causes for this:
> +terminated by OOM killer. There are several causes for this:
>
> 1. The cgroup limit is too low (just too low to do anything useful)
> 2. The user is using anonymous memory and swap is turned off or too low
> @@ -418,7 +517,7 @@ If we want to change this to 1G, we can
> # echo 1G > memory.soft_limit_in_bytes
>
> NOTE1: Soft limits take effect over a long period of time, since they involve
> - reclaiming memory for balancing between memory cgroups
> +reclaiming memory for balancing between memory cgroups
Why remove those leading spaces (indent/text alignment)?
Compare below.
> NOTE2: It is recommended to set the soft limit always below the hard limit,
> otherwise the hard limit will take precedence.
>
> @@ -495,27 +594,27 @@ It's applicable for root and non-root cg
>
> memory.oom_control file is for OOM notification and other controls.
>
> -Memory controler implements oom notifier using cgroup notification
> -API (See cgroups.txt). It allows to register multiple oom notification
> -delivery and gets notification when oom happens.
> +Memory cgroup implements OOM notifier using cgroup notification
> +API (See cgroups.txt). It allows to register multiple OOM notification
> +delivery and gets notification when OOM happens.
>
> To register a notifier, application need:
> - create an eventfd using eventfd(2)
> - open memory.oom_control file
> - write string like "<event_fd> <memory.oom_control>" to cgroup.event_control
>
> -Application will be notifier through eventfd when oom happens.
> +Application will be notifier through eventfd when OOM happens.
notified
> OOM notification doesn't work for root cgroup.
>
> -You can disable oom-killer by writing "1" to memory.oom_control file.
> +You can disable OOM-killer by writing "1" to memory.oom_control file.
> As.
> #echo 1 > memory.oom_control
>
> -This operation is only allowed to the top cgroup of subhierarchy.
> -If oom-killer is disabled, tasks under cgroup will hang/sleep
> -in memcg's oom-waitq when they request accountable memory.
> +This operation is only allowed to the top cgroup of sub-hierarchy.
> +If OOM-killer is disabled, tasks under cgroup will hang/sleep
> +in memory cgroup's OOM-waitqueue when they request accountable memory.
>
> -For running them, you have to relax the memcg's oom sitaution by
> +For running them, you have to relax the memory cgroup's OOM status by
> * enlarge limit or reduce usage.
> To reduce usage,
> * kill some tasks.
Almost there. :)
thanks,
---
~Randy
--
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/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>