On Tue, 2016-08-23 at 09:35 -0700, Jason Low wrote:
> On Tue, 2016-08-23 at 09:17 -0700, Davidlohr Bueso wrote:
> > I have not looked at the patches yet, but are there any performance minutia
> > to be aware of?
>
> This would remove all of the mutex architecture specific optimizations
> in the (common) fastpath, so that is one thing that could reduce
> performance. I'll run some benchmarks to see what some of the
> performance impacts of these patches would be.
I tested this patch on an 8 socket system with the high_systime AIM7
workload with diskfs. The patch provided big performance improvements in
terms of throughput in the highly contended cases.
-------------------------------------------------
| users | avg throughput | avg throughput |
| without patch | with patch |
-------------------------------------------------
| 10 - 90 | 13,943 JPM | 14,432 JPM |
-------------------------------------------------
| 100 - 900 | 75,475 JPM | 102,922 JPM |
-------------------------------------------------
| 1000 - 1900 | 77,299 JPM | 115,271 JPM |
-------------------------------------------------
Unfortunately, at 2000 users, the modified kernel locked up.
# INFO: task reaim:<#> blocked for more than 120 seconds.
So something appears to be buggy.
