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

From: Vladimir Davydov
Date: Wed Jul 09 2014 - 03:53:14 EST

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?

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