[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v8 00/10] qspinlock: a 4-byte queue spinlock with PV support
On 04/07/2014 02:14 AM, Raghavendra K T wrote: I tested the v7,v8 of qspinlock with unfair config on kvm guest.I was curious about unfair locks performance in undercommit cases. (overcommit case is expected to perform well)But I am seeing hang in overcommit cases. Gdb showed that many vcpus are halted and there was no progress. Suspecting the problem /race withhalting, 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? 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). What is the baseline for the performance improvement? Is it without the unfair lock and PV qspinlock? -Longman _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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