Messages in this thread | | | Date | Mon, 01 Sep 2008 14:47:26 +0530 | From | Balbir Singh <> | Subject | Re: [RFC][PATCH] Remove cgroup member from struct page |
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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).
-- Balbir
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