linux-kernel - Re: [PATCH RFC 0/5] Virtual Memory Resource Controller for cgroups

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Date:	Wed, 9 Jul 2014 11:52:52 +0400
From:	Vladimir Davydov <vdavydov@...allels.com>
To:	<linux-kernel@...r.kernel.org>
CC:	<linux-mm@...ck.org>, <cgroups@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, Li Zefan <lizefan@...wei.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>, Mel Gorman <mgorman@...e.de>,
	Rik van Riel <riel@...hat.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Hugh Dickins <hughd@...gle.com>,
	David Rientjes <rientjes@...gle.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Balbir Singh <bsingharora@...il.com>
Subject: Re: [PATCH RFC 0/5] Virtual Memory Resource Controller for cgroups

On Thu, Jul 03, 2014 at 04:48:16PM +0400, Vladimir Davydov wrote:
> Hi,
> 
> Typically, when a process calls mmap, it isn't given all the memory pages it
> requested immediately. Instead, only its address space is grown, while the
> memory pages will be actually allocated on the first use. If the system fails
> to allocate a page, it will have no choice except invoking the OOM killer,
> which may kill this or any other process. Obviously, it isn't the best way of
> telling the user that the system is unable to handle his request. It would be
> much better to fail mmap with ENOMEM instead.
> 
> That's why Linux has the memory overcommit control feature, which accounts and
> limits VM size that may contribute to mem+swap, i.e. private writable mappings
> and shared memory areas. However, currently it's only available system-wide,
> and there's no way of avoiding OOM in cgroups.
> 
> This patch set is an attempt to fill the gap. It implements the resource
> controller for cgroups that accounts and limits address space allocations that
> may contribute to mem+swap.
> 
> The interface is similar to the one of the memory cgroup except it controls
> virtual memory usage, not actual memory allocation:
> 
>   vm.usage_in_bytes            current vm usage of processes inside cgroup
>                                (read-only)
> 
>   vm.max_usage_in_bytes        max vm.usage_in_bytes, can be reset by writing 0
> 
>   vm.limit_in_bytes            vm.usage_in_bytes must be <= vm.limite_in_bytes;
>                                allocations that hit the limit will be failed
>                                with ENOMEM
> 
>   vm.failcnt                   number of times the limit was hit, can be reset
>                                by writing 0
> 
> In future, the controller can be easily extended to account for locked pages
> and shmem.

Any thoughts on this?

Thanks.
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