Gregory Haskins wrote: > Avi Kivity wrote: >> David S. Ahern wrote: >>> I ran another test case with SMT disabled, and while I was at it >>> converted TSC delta to operations/sec. The results without SMT are >>> confusing -- to me anyways. I'm hoping someone can explain it. >>> Basically, using a count of 10,000,000 (per your web page) with SMT >>> disabled the guest detected a soft lockup on the CPU. So, I dropped the >>> count down to 1,000,000. So, for 1e6 iterations: >>> >>> without SMT, with EPT: >>> HC: 259,455 ops/sec >>> PIO: 226,937 ops/sec >>> MMIO: 113,180 ops/sec >>> >>> without SMT, without EPT: >>> HC: 274,825 ops/sec >>> PIO: 247,910 ops/sec >>> MMIO: 111,535 ops/sec >>> >>> Converting the prior TSC deltas: >>> >>> with SMT, with EPT: >>> HC: 994,655 ops/sec >>> PIO: 875,116 ops/sec >>> MMIO: 439,738 ops/sec >>> >>> with SMT, without EPT: >>> HC: 994,304 ops/sec >>> PIO: 903,057 ops/sec >>> MMIO: 423,244 ops/sec >>> >>> Running the tests repeatedly I did notice a fair variability (as much as >>> -10% down from these numbers). >>> >>> Also, just to make sure I converted the delta to ops/sec, the formula I >>> used was cpu_freq / dTSC * count = operations/sec >>> >>> >> The only think I can think of is cpu frequency scaling lying about the >> cpu frequency. Really the test needs to use time and not the time >> stamp counter. >> >> Are the results expressed in cycles/op more reasonable? > > FWIW: I always used kvm_stat instead of my tsc printk > kvm_stat shows same approximate numbers as with the TSC-->ops/sec conversions. Interestingly, MMIO writes are not showing up as mmio_exits in kvm_stat; they are showing up as insn_emulation. david > -- 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
