Messages in this thread |  | | | Date | Tue, 3 Aug 2010 09:36:45 +0530 | | From | Balbir Singh <> | | Subject | Re: [PATCH -mm 5/5] memcg: use spinlock in page_cgroup instead of bit_spinlock |
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* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2010-08-02 19:20:06]:
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > This patch replaces bit_spinlock with spinlock. In general, > spinlock has good functinality than bit_spin_lock and we should use > it if we have a room for it. In 64bit arch, we have extra 4bytes. > Let's use it. > expected effects: > - use better codes. > - ticket lock on x86-64 > - para-vitualization aware lock > etc.. > > Chagelog: 20090729 > - fixed page_cgroup_is_locked(). > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > --
The additional space usage is a big concern, I think saving space would be of highest priority. I understand the expected benefits, but a spinlock_t per page_cgroup is quite expensive at the moment. If anything I think it should be a config option under CONFIG_DEBUG or something else to play with and see the side effects.
-- Three Cheers, Balbir
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