On Thu, Mar 11, 2010 at 01:49:08PM +0900, KAMEZAWA Hiroyuki wrote: > On Thu, 11 Mar 2010 13:31:23 +0900 > Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote: > > > On Wed, 10 Mar 2010 09:26:24 +0530, Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote: > > > * nishimura@xxxxxxxxxxxxxxxxx <nishimura@xxxxxxxxxxxxxxxxx> [2010-03-10 10:43:09]: > > > I made a patch(attached) using both local_irq_disable/enable and local_irq_save/restore. > > local_irq_save/restore is used only in mem_cgroup_update_file_mapped. > > > > And I attached a histogram graph of 30 times kernel build in root cgroup for each. > > > > before_root: no irq operation(original) > > after_root: local_irq_disable/enable for all > > after2_root: local_irq_save/restore for all > > after3_root: mixed version(attached) > > > > hmm, there seems to be a tendency that before < after < after3 < after2 ? > > Should I replace save/restore version to mixed version ? > > > > IMHO, starting from after2_root version is the easist. > If there is a chance to call lock/unlock page_cgroup can be called in > interrupt context, we _have to_ disable IRQ, anyway. > And if we have to do this, I prefer migration_lock rather than this mixture. > > BTW, how big your system is ? Balbir-san's concern is for bigger machines. > But I'm not sure this change is affecte by the size of machines. > I'm sorry I have no big machine, now. FWIW, I took andrea's patches (local_irq_save/restore solution) and compiled the kernel on 32 cores hyperthreaded (64 cpus) with make -j32 in /dev/shm/. On this system, I can't see much difference. I compiled the kernel 10 times and took average. Without andrea's patches: 28.698 (seconds) With andrea's patches: 28.711 (seconds). Diff is .04% This is all should be in root cgroup. Note, I have not mounted memory cgroup controller but it is compiled in. So I am assuming that root group accounting will still be taking place. Also assuming that it is not required to do actual IO to disk and /dev/shm is enough to see the results of local_irq_save()/restore. Thanks Vivek -- 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>