On Mon, 28 Mar 2011 19:46:41 -0700
Ying Han [off-list ref] wrote:

On Mon, Mar 28, 2011 at 5:47 PM, KAMEZAWA Hiroyuki
[off-list ref] wrote:

quoted

quoted

By saying that, memcg simplified the memory accounting per-cgroup but
the memory isolation is broken. This is one of examples where pages
are shared between global LRU and per-memcg LRU. It is easy to get
cgroup-A's page evicted by adding memory pressure to cgroup-B.

If you overcommit....Right ?

yes, we want to support the configuration of over-committing the
machine w/ limit_in_bytes.

Then, soft_limit is a feature for fixing the problem. If you have problem
with soft_limit, let's fix it.

quoted

quoted

The approach we are thinking to make the page->lru exclusive solve the
problem. and also we should be able to break the zone->lru_lock
sharing.

Is zone->lru_lock is a problem even with the help of pagevecs ?

quoted

If LRU management guys acks you to isolate LRUs and to make kswapd etc..
more complex, okay, we'll go that way.

I would assume the change only apply to memcg users , otherwise
everything is leaving in the global LRU list.

This will _change_ the whole memcg design and concepts Maybe memcg
should have some kind of balloon driver to

quoted

work happy with isolated lru.

We have soft_limit hierarchical reclaim for system memory pressure,
and also we will add per-memcg background reclaim. Both of them do
targeting reclaim on per-memcg LRUs, and where is the balloon driver
needed?

If soft_limit is _not_ enough. And I think you background reclaim should
be work with soft_limit and be triggered by global memory pressure. 

As wrote in other mail, it's not called via direct reclaim.
Maybe its the 1st point to be shooted rather than trying big change.




Thanks,
-Kame

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