On Wed, 2013-06-19 at 16:11 -0700, Davidlohr Bueso wrote: > On Mon, 2013-06-17 at 17:08 -0700, Tim Chen wrote: > > On Mon, 2013-06-17 at 16:35 -0700, Davidlohr Bueso wrote: > > > On Tue, 2013-06-18 at 07:20 +0800, Alex Shi wrote: > > > > On 06/18/2013 12:22 AM, Davidlohr Bueso wrote: > > > > > After a lot of benchmarking, I finally got the ideal results for aim7, > > > > > so far: this patch + optimistic spinning with preemption disabled. Just > > > > > like optimistic spinning, this patch by itself makes little to no > > > > > difference, yet combined is where we actually outperform 3.10-rc5. In > > > > > addition, I noticed extra throughput when disabling preemption in > > > > > try_optimistic_spin(). > > > > > > > > > > With i_mmap as a rwsem and these changes I could see performance > > > > > benefits for alltests (+14.5%), custom (+17%), disk (+11%), high_systime > > > > > (+5%), shared (+15%) and short (+4%), most of them after around 500 > > > > > users, for fewer users, it made little to no difference. > > > > > > > > A pretty good number. what's the cpu number in your machine? :) > > > > > > 8-socket, 80 cores (ht off) > > > > > > > > > > David, > > > > I wonder if you are interested to try the experimental patch below. > > It tries to avoid unnecessary writes to the sem->count when we are > > going to fail the down_write by executing rwsem_down_write_failed_s > > instead of rwsem_down_write_failed. It should further reduce the > > cache line bouncing. It didn't make a difference for my > > workload. Wonder if it may help yours more in addition to the > > other two patches. Right now the patch is an ugly hack. I'll merge > > rwsem_down_write_failed_s and rwsem_down_write_failed into one > > function if this approach actually helps things. > > > > I tried this on top of the patches we've already been dealing with. It > actually did more harm than good. Only got a slight increase in the > five_sec workload, for the rest either no effect, or negative. So far > the best results are still with spin on owner + preempt disable + Alex's > patches. > Thanks for trying it out. A little disappointed as I was expecting no change in performance for the worst case. Tim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>