On Sun, 2013-06-02 at 00:51 +0530, Raghavendra K T wrote: > This series replaces the existing paravirtualized spinlock mechanism > with a paravirtualized ticketlock mechanism. The series provides > implementation for both Xen and KVM. > > Changes in V9: > - Changed spin_threshold to 32k to avoid excess halt exits that are > causing undercommit degradation (after PLE handler improvement). > - Added kvm_irq_delivery_to_apic (suggested by Gleb) > - Optimized halt exit path to use PLE handler > > V8 of PVspinlock was posted last year. After Avi's suggestions to look > at PLE handler's improvements, various optimizations in PLE handling > have been tried. Sorry for not posting this sooner. I have tested the v9 pv-ticketlock patches in 1x and 2x over-commit with 10-vcpu and 20-vcpu VMs. I have tested these patches with and without PLE, as PLE is still not scalable with large VMs. System: x3850X5, 40 cores, 80 threads 1x over-commit with 10-vCPU VMs (8 VMs) all running dbench: ---------------------------------------------------------- Total Configuration Throughput(MB/s) Notes 3.10-default-ple_on 22945 5% CPU in host kernel, 2% spin_lock in guests 3.10-default-ple_off 23184 5% CPU in host kernel, 2% spin_lock in guests 3.10-pvticket-ple_on 22895 5% CPU in host kernel, 2% spin_lock in guests 3.10-pvticket-ple_off 23051 5% CPU in host kernel, 2% spin_lock in guests [all 1x results look good here] 2x over-commit with 10-vCPU VMs (16 VMs) all running dbench: ----------------------------------------------------------- Total Configuration Throughput Notes 3.10-default-ple_on 6287 55% CPU host kernel, 17% spin_lock in guests 3.10-default-ple_off 1849 2% CPU in host kernel, 95% spin_lock in guests 3.10-pvticket-ple_on 6691 50% CPU in host kernel, 15% spin_lock in guests 3.10-pvticket-ple_off 16464 8% CPU in host kernel, 33% spin_lock in guests [PLE hinders pv-ticket improvements, but even with PLE off, we still off from ideal throughput (somewhere >20000)] 1x over-commit with 20-vCPU VMs (4 VMs) all running dbench: ---------------------------------------------------------- Total Configuration Throughput Notes 3.10-default-ple_on 22736 6% CPU in host kernel, 3% spin_lock in guests 3.10-default-ple_off 23377 5% CPU in host kernel, 3% spin_lock in guests 3.10-pvticket-ple_on 22471 6% CPU in host kernel, 3% spin_lock in guests 3.10-pvticket-ple_off 23445 5% CPU in host kernel, 3% spin_lock in guests [1x looking fine here] 2x over-commit with 20-vCPU VMs (8 VMs) all running dbench: ---------------------------------------------------------- Total Configuration Throughput Notes 3.10-default-ple_on 1965 70% CPU in host kernel, 34% spin_lock in guests 3.10-default-ple_off 226 2% CPU in host kernel, 94% spin_lock in guests 3.10-pvticket-ple_on 1942 70% CPU in host kernel, 35% spin_lock in guests 3.10-pvticket-ple_off 8003 11% CPU in host kernel, 70% spin_lock in guests [quite bad all around, but pv-tickets with PLE off the best so far. Still quite a bit off from ideal throughput] In summary, I would state that the pv-ticket is an overall win, but the current PLE handler tends to "get in the way" on these larger guests. -Andrew -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
