Date: Tue, 10 Jun 2008 09:14:39 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Andrea Righi <righi.andrea@gmail.com>
Cc: balbir@linux.vnet.ibm.com, menage@google.com,
       kosaki.motohiro@jp.fujitsu.com, xemul@openvz.org,
       linux-kernel@vger.kernel.org, containers@lists.osdl.org
Subject: Re: [RFC PATCH 0/5] memcg: VM overcommit accounting and handling
Message-Id: <20080610091439.04061da9.kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <1213054383-18137-1-git-send-email-righi.andrea@gmail.com>
References: <1213054383-18137-1-git-send-email-righi.andrea@gmail.com>
Organization: Fujitsu
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2921
Lines: 79

On Tue, 10 Jun 2008 01:32:58 +0200
Andrea Righi <righi.andrea@gmail.com> wrote:

> 
> Provide distinct cgroup VM overcommit accounting and handling using the memory
> resource controller.
> 

Could you explain the benefits of this even when we have memrlimit controller ?
(If unsure, see 2.6.26-rc5-mm1 and search memrlimit controller.)

And this kind of virtual-address-handling things should be implemented on
memrlimit controller (means not on memory-resource-controller.).
It seems this patch doesn't need to handle page_group.

Considering hierarchy, putting several kinds of features on one controller is
not good, I think. Balbir, how do you think ?

Thanks,
-Kame


> Patchset against latest Linus git tree.
> 
> This patchset allows to set different per-cgroup overcommit rules and,
> according to them, it's possible to return a memory allocation failure (ENOMEM)
> to the applications, instead of always triggering the OOM killer via
> mem_cgroup_out_of_memory() when cgroup memory limits are exceeded.
> 
> Default overcommit settings are taken from vm.overcommit_memory and
> vm.overcommit_ratio sysctl values. Child cgroups initially inherits the VM
> overcommit parent's settings.
> 
> Cgroup overcommit settings can be overridden using memory.overcommit_memory and
> memory.overcommit_ratio files under the cgroup filesystem.
> 
> For example:
> 
> 1. Initialize a cgroup with 50MB memory limit:
> # mount -t cgroup none /cgroups -o memory
> # mkdir /cgroups/0
> # /bin/echo $$ >  /cgroups/0/tasks
> # /bin/echo 50M > /cgroups/0/memory.limit_in_bytes
> 
> 2. Use the "never overcommit" policy with 50% ratio:
> # /bin/echo 2 > /cgroups/0/memory.overcommit_memory
> # /bin/echo 50 > /cgroups/0/memory.overcommit_ratio
> 
> Assuming we have no swap space, cgroup 0 can allocate up to 25MB of virtual
> memory. If that limit is exceeded all the further allocation attempts made by
> userspace applications will receive a -ENOMEM.
> 
> 4. Show committed VM statistics:
> # cat /cgroups/0/memory.overcommit_as
> CommitLimit:     25600 kB
> Committed_AS:     9844 kB
> 
> 5. Use "always overcommmit":
> # /bin/echo 1 > /cgroups/0/memory.overcommit_memory
> 
> This is very similar to the default memory controller configuration: overcommit
> is allowed, but when there's no more available memory oom-killer is invoked.
> 
> TODO:
> - shared memory is not taken in account (i.e. files in tmpfs)
> 
> -Andrea
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/