Messages in this thread |  | | | Date | Mon, 01 Sep 2008 13:43:18 +0400 | | From | Pavel Emelyanov <> | | Subject | Re: [RFC][PATCH] Remove cgroup member from struct page |
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Balbir Singh wrote: > Pavel Emelyanov wrote: >> Balbir Singh wrote: >>> This is a rewrite of a patch I had written long back to remove struct page >>> (I shared the patches with Kamezawa, but never posted them anywhere else). >>> I spent the weekend, cleaning them up for 2.6.27-rc5-mmotm (29 Aug 2008). >>> >>> I've tested the patches on an x86_64 box, I've run a simple test running >>> under the memory control group and the same test running concurrently under >>> two different groups (and creating pressure within their groups). I've also >>> compiled the patch with CGROUP_MEM_RES_CTLR turned off. >>> >>> Advantages of the patch >>> >>> 1. It removes the extra pointer in struct page >>> >>> Disadvantages >>> >>> 1. It adds an additional lock structure to struct page_cgroup >>> 2. Radix tree lookup is not an O(1) operation, once the page is known >>> getting to the page_cgroup (pc) is a little more expensive now. >> And besides, we also have a global lock, that protects even lookup >> from this structure. Won't this affect us too much on bug-smp nodes? > > Sorry, not sure I understand. The lookup is done under RCU. Updates are done > using the global lock. It should not be hard to make the radix tree per node > later (as an iterative refinement). >
OOPS, indeed. Sorry for the confusion, then. :)
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