Re: [PATCH v8 74/74] cputlb: queue async flush jobs without the BQL

[Alex Bennée]

Robert Foley <address@hidden> writes:

> From: "Emilio G. Cota" <address@hidden>
>
> This yields sizable scalability improvements, as the below results show.
>
> Host: Two Intel E5-2683 v3 14-core CPUs at 2.00 GHz (Haswell)
>
> Workload: Ubuntu 18.04 ppc64 compiling the linux kernel with
> "make -j N", where N is the number of cores in the guest.
>
<snip>

So my numbers running a aarch64 guest running pigz with an x86_64 host
the gains start to tail off past -smp 12 but still seem to be showing
some gain up to -smp 16 (the host has 24 cores):

  ./aarch64-softmmu/qemu-system-aarch64 -machine 
virt,graphics=on,gic-version=3,virtualization=on -cpu cortex-a53 -serial 
mon:stdio -nic user,model=virtio-net-pci,hostfwd=tcp::2222-:22 -device 
virtio-scsi-pci -device scsi-hd,drive=hd0 -blockdev 
driver=raw,node-name=hd0,discard=unmap,file.driver=host_device,file.filename=/dev/zvol/hackpool-0/debian-buster-arm64
 -kernel ../../../linux.git/builds/arm64.nopreempt/arch/arm64/boot/Image 
-append "console=ttyAMA0 root=/dev/sda2 systemd.unit=benchmark-pigz.service" 
-display none -m 4096 -snapshot -smp $SMP

  | Command                     | Mean [s]         |    Min...Max [s] |
  |-----------------------------+------------------+------------------|
  | =$QEMU $QEMU_ARGS  -smp 4=  | 146.738 ± 62.272 | 43.861...246.139 |
  | =$QEMU $QEMU_ARGS  -smp 5=  | 33.984 ± 13.370  |  29.501...72.032 |
  | =$QEMU $QEMU_ARGS  -smp 6=  | 26.128 ± 0.189   |  25.837...26.475 |
  | =$QEMU $QEMU_ARGS  -smp 7=  | 23.459 ± 0.090   |  23.252...23.560 |
  | =$QEMU $QEMU_ARGS  -smp 8=  | 21.579 ± 0.117   |  21.418...21.764 |
  | =$QEMU $QEMU_ARGS  -smp 9=  | 20.163 ± 0.142   |  19.938...20.387 |
  | =$QEMU $QEMU_ARGS  -smp 10= | 19.028 ± 0.106   |  18.877...19.183 |
  | =$QEMU $QEMU_ARGS  -smp 11= | 18.166 ± 0.093   |  18.081...18.386 |
  | =$QEMU $QEMU_ARGS  -smp 12= | 17.464 ± 0.067   |  17.383...17.614 |
  | =$QEMU $QEMU_ARGS  -smp 13= | 16.928 ± 0.104   |  16.754...17.158 |
  | =$QEMU $QEMU_ARGS  -smp 14= | 16.615 ± 0.188   |  16.486...17.105 |
  | =$QEMU $QEMU_ARGS  -smp 15= | 16.344 ± 0.176   |  16.094...16.680 |
  | =$QEMU $QEMU_ARGS  -smp 16= | 16.085 ± 0.215   |  15.869...16.623 |

-- 
Alex Bennée