On Wed, 31 May 2023 09:57:34 +0000 Qi Zheng <qi.zheng@xxxxxxxxx> wrote:
> From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
>
> Hi all,
>
> This patch series aims to make unregistration of super_block shrinker more
> faster.
>
> 1. Background
> =============
>
> The kernel test robot noticed a -88.8% regression of stress-ng.ramfs.ops_per_sec
> on commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). More
> details can be seen from the link[1] below.
>
> [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@xxxxxxxxx/
>
> We can just use the following command to reproduce the result:
>
> stress-ng --timeout 60 --times --verify --metrics-brief --ramfs 9 &
>
> 1) before commit f95bdb700bc6b:
>
> stress-ng: info: [11023] dispatching hogs: 9 ramfs
> stress-ng: info: [11023] stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s
> stress-ng: info: [11023] (secs) (secs) (secs) (real time) (usr+sys time)
> stress-ng: info: [11023] ramfs 774966 60.00 10.18 169.45 12915.89 4314.26
> stress-ng: info: [11023] for a 60.00s run time:
> stress-ng: info: [11023] 1920.11s available CPU time
> stress-ng: info: [11023] 10.18s user time ( 0.53%)
> stress-ng: info: [11023] 169.44s system time ( 8.82%)
> stress-ng: info: [11023] 179.62s total time ( 9.35%)
> stress-ng: info: [11023] load average: 8.99 2.69 0.93
> stress-ng: info: [11023] successful run completed in 60.00s (1 min, 0.00 secs)
>
> 2) after commit f95bdb700bc6b:
>
> stress-ng: info: [37676] dispatching hogs: 9 ramfs
> stress-ng: info: [37676] stressor bogo ops real time usrtime sys time bogo ops/s bogo ops/s
> stress-ng: info: [37676] (secs) (secs) (secs) (real time) (usr+sys time)
> stress-ng: info: [37676] ramfs 168673 60.00 1.61 39.66 2811.08 4087.47
> stress-ng: info: [37676] for a 60.10s run time:
> stress-ng: info: [37676] 1923.36s available CPU time
> stress-ng: info: [37676] 1.60s user time ( 0.08%)
> stress-ng: info: [37676] 39.66s system time ( 2.06%)
> stress-ng: info: [37676] 41.26s total time ( 2.15%)
> stress-ng: info: [37676] load average: 7.69 3.63 2.36
> stress-ng: info: [37676] successful run completed in 60.10s (1 min, 0.10 secs)
Is this comparison reversed? It appears to demonstrate that
f95bdb700bc6b made the operation faster.
