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. Regards, Wanpeng Li
