On Wed, Dec 20, 2017 at 02:44:25PM +0800, Wanpeng Li wrote: > Hi Yury, > 2017-12-19 16:50 GMT+08:00 Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>: > > This benchmark sends many IPIs in different modes and measures > > time for IPI delivery (first column), and total time, ie including > > time to acknowledge the receive by sender (second column). > > > > The scenarios are: > > Dry-run: do everything except actually sending IPI. Useful > > to estimate system overhead. > > Self-IPI: Send IPI to self CPU. > > Normal IPI: Send IPI to some other CPU. > > Broadcast IPI: Send broadcast IPI to all online CPUs. > > Broadcast lock: Send broadcast IPI to all online CPUs and force them > > acquire/release spinlock. > > > > The raw output looks like this: > > [ 155.363374] Dry-run: 0, 2999696 ns > > [ 155.429162] Self-IPI: 30385328, 65589392 ns > > [ 156.060821] Normal IPI: 566914128, 631453008 ns > > [ 158.384427] Broadcast IPI: 0, 2323368720 ns > > [ 160.831850] Broadcast lock: 0, 2447000544 ns > > > > For virtualized guests, sending and reveiving IPIs causes guest exit. > > I used this test to measure performance impact on KVM subsystem of > > Christoffer Dall's series "Optimize KVM/ARM for VHE systems" [1]. > > > > Test machine is ThunderX2, 112 online CPUs. Below the results normalized > > to host dry-run time, broadcast lock results omitted. Smaller - better. > > Could you test on a x86 box? I see a lot of calltraces on my haswell > client host, there is no calltrace in the guest, however, I can still > observe "Invalid parameters" warning when insmod this module. In > addition, the x86 box fails to boot when ipi_benchmark is buildin. I tried to boot kernel with builtin test both on real hardware and qemu+kvm - no calltraces or other problems. Kernel is 4.14, config for host is attached. CPU is Intel(R) Core(TM) i7-7600U CPU @ 2.80GHz Kernel is 4.14, config for host is attached, but it's default Ubuntu config. Results and qemu command are below. Could you share more details about your configuration? Yury qemu-system-x86_64 -hda debian_squeeze_amd64_standard.qcow2 \ -smp 1 -curses --nographic --enable-kvm Host, 4 cores: [ 0.237279] Dry-run: 0, 170292 ns [ 0.643269] Self-IPI: 458516336, 922256372 ns [ 0.902545] Self-IPI: 508518362, 972130665 ns [ 0.646500] Broadcast IPI: 0, 97301545 ns [ 0.649712] Broadcast lock: 0, 102364755 ns KVM, single core: [ 0.237279] Dry-run: 0, 124500 ns [ 0.643269] Self-IPI: 202518310, 405444790 ns [ 0.643694] Normal IPI FAILED: -2 [ 0.646500] Broadcast IPI: 0, 2524370 ns [ 0.649712] Broadcast lock: 0, 2642270 ns KVM, 4 cores: [ 0.492676] Dry-run: 0, 126380 ns [ 0.902545] Self-IPI: 204085450, 409863800 ns [ 2.179676] Normal IPI: 1058014940, 1276742820 ns [ 3.396132] Broadcast IPI: 0, 1215934730 ns [ 4.610719] Broadcast lock: 0, 1213945500 ns
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