Re: [RFC][PATCH 2/5] memcg: uncharge in batched manner

From: Balbir Singh
Date: Fri Aug 28 2009 - 12:03:54 EST

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> [2009-08-29 00:21:50]:

> > tof unmap_vmas, exit_mmap, etc so that we don't have to keep
> > additional data structures around.
> >
> We can't. We uncharge when page->mapcount goes down to 0.
> This is unknown until page_remove_rmap() decrement page->mapcount
> by "atomic" ops.
> My first version allocated memcg_batch_info on stack ...and..
> I had to pass an extra argument to page_remove_rmap() etc....
> That was very ugly ;(
> Now, I adds per-task memcg_batch_info to task struct.
> Because it will be always used at exit() and make exit() path
> much faster, it's not very costly.

Aaah.. I see that makes a lot of sense. Thanks for the clarification.

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