Re: [PATCH 1/2] mwifiex: Use non-posted PCI register writes

Brian Norris
2021-09-01T21:07:50Z

Apologies for the brain-dead mailer. I forget that I should only reply
via web when I _want_ text wrapping:

On Wed, Sep 01, 2021 at 02:04:04PM -0700, Brian Norris wrote:
> (b) latency spikes to ~6ms:
> # trace-cmd record -p function_graph -O funcgraph-abstime -l
> mwifiex_pm_wakeup_card
> # trace-cmd report
> kworker/u13:0-199 [003] 348.987306: funcgraph_entry: #
> 6219.500 us | mwifiex_pm_wakeup_card();
> kworker/u13:0-199 [003] 349.316312: funcgraph_entry: #
> 6267.625 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-4057 [001] 352.238530: funcgraph_entry: #
> 6184.250 us | mwifiex_pm_wakeup_card();
> kworker/u13:0-199 [002] 356.626366: funcgraph_entry: #
> 6553.166 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-4057 [002] 356.709389: funcgraph_entry: #
> 6212.500 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-4057 [002] 356.847215: funcgraph_entry: #
> 6230.292 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-4057 [000] 356.897576: funcgraph_entry: #
> 6451.667 us | mwifiex_pm_wakeup_card();
> kworker/u13:0-199 [004] 357.175025: funcgraph_entry: #
> 6204.042 us | mwifiex_pm_wakeup_card();
>
> whereas it used to look more like:
>
> kworker/u13:1-173 [005] 212.230542: funcgraph_entry:
> 7.000 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-1768 [005] 213.886063: funcgraph_entry:
> 9.334 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-1768 [002] 214.473273: funcgraph_entry: +
> 11.375 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-1768 [005] 214.530705: funcgraph_entry:
> 5.542 us | mwifiex_pm_wakeup_card();
> kworker/u13:1-173 [002] 215.050168: funcgraph_entry: +
> 13.125 us | mwifiex_pm_wakeup_card();
> kworker/u13:1-173 [002] 215.106492: funcgraph_entry: +
> 11.959 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-1768 [005] 215.484807: funcgraph_entry:
> 8.459 us | mwifiex_pm_wakeup_card();
> kworker/u13:1-173 [003] 215.515238: funcgraph_entry: +
> 15.166 us | mwifiex_pm_wakeup_card();
> kworker/u13:3-1768 [001] 217.175691: funcgraph_entry: +
> 11.083 us | mwifiex_pm_wakeup_card();

That should read:

# trace-cmd record -p function_graph -O funcgraph-abstime -l mwifiex_pm_wakeup_card
# trace-cmd report
kworker/u13:0-199 [003] 348.987306: funcgraph_entry: # 6219.500 us | mwifiex_pm_wakeup_card();
kworker/u13:0-199 [003] 349.316312: funcgraph_entry: # 6267.625 us | mwifiex_pm_wakeup_card();
kworker/u13:3-4057 [001] 352.238530: funcgraph_entry: # 6184.250 us | mwifiex_pm_wakeup_card();
kworker/u13:0-199 [002] 356.626366: funcgraph_entry: # 6553.166 us | mwifiex_pm_wakeup_card();
kworker/u13:3-4057 [002] 356.709389: funcgraph_entry: # 6212.500 us | mwifiex_pm_wakeup_card();
kworker/u13:3-4057 [002] 356.847215: funcgraph_entry: # 6230.292 us | mwifiex_pm_wakeup_card();
kworker/u13:3-4057 [000] 356.897576: funcgraph_entry: # 6451.667 us | mwifiex_pm_wakeup_card();
kworker/u13:0-199 [004] 357.175025: funcgraph_entry: # 6204.042 us | mwifiex_pm_wakeup_card();

vs.

kworker/u13:1-173 [005] 212.230542: funcgraph_entry: 7.000 us | mwifiex_pm_wakeup_card();
kworker/u13:3-1768 [005] 213.886063: funcgraph_entry: 9.334 us | mwifiex_pm_wakeup_card();
kworker/u13:3-1768 [002] 214.473273: funcgraph_entry: + 11.375 us | mwifiex_pm_wakeup_card();
kworker/u13:3-1768 [005] 214.530705: funcgraph_entry: 5.542 us | mwifiex_pm_wakeup_card();
kworker/u13:1-173 [002] 215.050168: funcgraph_entry: + 13.125 us | mwifiex_pm_wakeup_card();
kworker/u13:1-173 [002] 215.106492: funcgraph_entry: + 11.959 us | mwifiex_pm_wakeup_card();
kworker/u13:3-1768 [005] 215.484807: funcgraph_entry: 8.459 us | mwifiex_pm_wakeup_card();
kworker/u13:1-173 [003] 215.515238: funcgraph_entry: + 15.166 us | mwifiex_pm_wakeup_card();
kworker/u13:3-1768 [001] 217.175691: funcgraph_entry: + 11.083 us | mwifiex_pm_wakeup_card();

Brian