Messages in this thread | | | Date | Mon, 07 Apr 2014 23:21:46 +0530 | From | Raghavendra K T <> | Subject | Re: [PATCH v8 00/10] qspinlock: a 4-byte queue spinlock with PV support |
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On 04/07/2014 10:08 PM, Waiman Long wrote: > On 04/07/2014 02:14 AM, Raghavendra K T wrote: [...] >> But I am seeing hang in overcommit cases. Gdb showed that many vcpus >> are halted and there was no progress. Suspecting the problem /race with >> halting, I removed the halt() part of kvm_hibernate(). I am yet to >> take a closer look at the code on halt() related changes. > > It seems like there may still be race conditions where the current code > is not handling correctly. I will look into that to see where the > problem is. BTW, what test do you use to produce the hang condition?
Running ebizzy on 2 of the vms simultaneously (for sometime in repeated loop) could reproduce it.
>> Patch series with that change gave around 20% improvement for dbench >> 2x and 30% improvement for ebizzy 2x cases. (1x has no significant >> loss/gain). >>
While at it, Just a correction it was 30% for ebizzy1.5x and around 80% for ebizzy 2x.
> What is the baseline for the performance improvement? Is it without the > unfair lock and PV qspinlock?
Baseline was 3.14-rc8 without any of the qspin patch series.
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