On Tue, 2014-01-28 at 13:08 -0800, Davidlohr Bueso wrote: > On Tue, 2014-01-28 at 11:13 -0800, Jason Low wrote: > > v1->v2: > > - Replace the previous patch that limits the # of times a thread can spin > > with > > !lock->owner with a patch that releases the mutex before holding the > > wait_lock > > in the __mutex_unlock_common_slowpath() function. > > - Add a patch which allows a thread to attempt 1 mutex_spin_on_owner() > > without > > checking need_resched() if need_resched() triggered while in the MCS > > queue. > > - Add a patch which disables preemption between modifying lock->owner and > > acquiring/releasing the mutex. > > > > This patchset addresses a few scalability issues with mutexes. > > > > Patch 1 has the mutex_can_spin_on_owner() funtion check for need_resched() > > before being added to MCS queue. > > > > Patches 2, 3 are to fix issues with threads spinning when > > there is no lock owner when the mutex is under high contention. > > > > Patch 4 and 5 are RFC patches. Patch 4 disables preemption between modifying > > lock->owner and locking/unlocking the mutex. Patch 5 addresses the situation > > where spinners can potentially wait a long time in the MCS queue for a > > chance > > to spin on mutex owner (not checking for need_resched()), yet ends up not > > getting to spin. > > > > These changes benefit the AIM7 fserver and high_systime workloads (run on > > disk) > > on an 8 socket, 80 core box. The table below shows the performance > > improvements with 3.13 + patches 1, 2, 3 when compared to the 3.13 baseline, > > and the performance improvements with 3.13 + all 5 patches compared to > > the 3.13 baseline. > > A lot of these changes are quite subtle. It would be good to see how > smaller systems are impacted with other workloads, not only big servers. > Since you see improvement in fserver, perhaps similar workloads could > also be of use: fio, filebench, postmark, fstress, etc.
Okay, I will include the numbers I collect on smaller systems next time (even if the % difference is small). Thanks, Jason -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
