* Waiman Long <waiman.long@xxxxxx> wrote: > On 09/05/2013 09:31 AM, Ingo Molnar wrote: > >* Waiman Long<waiman.long@xxxxxx> wrote: > > > > > >>The latest tty patches did work. The tty related spinlock contention > >>is now completely gone. The short workload can now reach over 8M JPM > >>which is the highest I have ever seen. > >> > >>The perf profile was: > >> > >>5.85% reaim reaim [.] mul_short > >>4.87% reaim [kernel.kallsyms] [k] ebitmap_get_bit > >>4.72% reaim reaim [.] mul_int > >>4.71% reaim reaim [.] mul_long > >>2.67% reaim libc-2.12.so [.] __random_r > >>2.64% reaim [kernel.kallsyms] [k] lockref_get_not_zero > >>1.58% reaim [kernel.kallsyms] [k] copy_user_generic_string > >>1.48% reaim [kernel.kallsyms] [k] mls_level_isvalid > >>1.35% reaim [kernel.kallsyms] [k] find_next_bit > >6%+ spent in ebitmap_get_bit() and mls_level_isvalid() looks like > >something worth optimizing. > > > >Is that called very often, or is it perhaps cache-bouncing for some > >reason? > > The high cycle count is due more to inefficient algorithm in the > mls_level_isvalid() function than cacheline contention in the code. The > attached patch should address this problem. It is in linux-next and > hopefully will be merged in 3.12. Great! If/when you happen to boot the latest & greatest kernel that has all these scalability patches applied it would be nice if you could send an updated profile into this thread. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
