On Thu, 7 Oct 2010 10:54:56 +0900 Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote: > On Thu, 7 Oct 2010 09:35:45 +0900 > KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > > On Wed, 6 Oct 2010 09:15:34 +0900 > > Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > > > > > First of all, we could add your patch as it is and I don't expect any > > > regression report about interrupt latency. > > > That's because many embedded guys doesn't use mmotm and have a > > > tendency to not report regression of VM. > > > Even they don't use memcg. Hmm... > > > > > > I pass the decision to MAINTAINER Kame and Balbir. > > > Thanks for the detail explanation. > > > > > > > Hmm. IRQ delay is a concern. So, my option is this. How do you think ? > > > > 1. remove local_irq_save()/restore() in lock/unlock_page_cgroup(). > > yes, I don't like it. > > > > 2. At moving charge, do this: > > a) lock_page()/ or trylock_page() > > b) wait_on_page_writeback() > > c) do move_account under lock_page_cgroup(). > > c) unlock_page() > > > > > > Then, Writeback updates will never come from IRQ context while > > lock/unlock_page_cgroup() is held by move_account(). There will be no race. > > > hmm, if we'll do that, I think we need to do that under pte_lock in > mem_cgroup_move_charge_pte_range(). But, we can't do wait_on_page_writeback() > under pte_lock, right? Or, we need re-organize current move-charge implementation. > Nice catch. I think releaseing pte_lock() is okay. (and it should be released) IIUC, task's css_set() points to new cgroup when "move" is called. Then, it's not necessary to take pte_lock, I guess. (And taking pte_lock too long is not appreciated..) I'll write a sample patch today. Thanks, -Kame > Thanks, > Daisuke Nishimura. > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>