Messages in this thread | | | Date | Wed, 11 Dec 2019 15:46:14 +0100 | From | Greg KH <> | Subject | Re: Patch "mm, vmstat: make quiet_vmstat lighter" has been added to the 4.4-stable tree |
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On Wed, Dec 11, 2019 at 10:32:49PM +0800, zhangyi (F) wrote: > Hi, all > > We find a performance degradation under lmbench af_unix[1] test case after > mergeing this patch on my x86 qemu 4.4 machine. The test result is basically > stable for each teses. > > Host machine: CPU: Intel(R) Xeon(R) CPU E5-2690 v3 > CPU(s): 48 > MEM: 193047 MB > > Guest machine: CPU: QEMU Virtual CPU version 2.5+ > CPU(s): 8 > MEM: 26065 MB > > Before this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 133.7073 microseconds > > After this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 156.4722 microseconds > > If we set task to a constant cpu, the degradation does not appear. > > Before this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 17.9296 microseconds > > After this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 17.7500 microseconds > > We also test it on the aarch64 hi1215 machine with 8 cpu cores. > > Before this patch: > [root@localhost ~]# ./lat_unix -P 1 > AF_UNIX sock stream latency: 30.7 microseconds > > After this patch: > [root@localhost ~]# ./lat_unix -P 1 > AF_UNIX sock stream latency: 37.5 microseconds > > Accessories included my reproduce config for x86 qemu. Any thoughts?
This fixes a bug, as reported by Daniel Wagner. So it's probably better to have a stable system instead of a broken one, right? :)
Daniel can provide more information if needed.
What about when you run your tests on a 4.9 or newer kernel that already has this integrated?
thanks,
greg k-h
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