linux-kernel - Re: [RFC 00/13] perf: Add perf kwork

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Date:   Wed, 22 Jun 2022 09:59:13 -0500
From:   "Paul A. Clarke" <pc@...ibm.com>
To:     Yang Jihong <yangjihong1@...wei.com>
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...nel.org, namhyung@...nel.org,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [RFC 00/13] perf: Add perf kwork

On Mon, Jun 13, 2022 at 05:45:52PM +0800, Yang Jihong wrote:
> Sometimes, we need to analyze time properties of kernel work such as irq,
> softirq, and workqueue, such as delay and running time of specific interrupts.
> Currently, these events have kernel tracepoints, but perf tool does not
> directly analyze the delay of these events
> 
> The perf-kwork tool is used to trace time properties of kernel work
> (such as irq, softirq, and workqueue), including runtime, latency,
> and timehist, using the infrastructure in the perf tools to allow
> tracing extra targets
> 
> test case:
> 
>   # perf kwork report
> 
>     Kwork Name                | Cpu  | Total Runtime | Frequency | Max runtime   | Max runtime start   | Max runtime end     |
>    ---------------------------------------------------------------------------------------------------------------------------
>     (s)RCU:9                  | 0007 |      3.488 ms |      1258 |      0.145 ms |    3398384.220013 s |    3398384.220157 s |
>     (s)NET_RX:3               | 0003 |      1.866 ms |       156 |      0.042 ms |    3398385.629764 s |    3398385.629806 s |
>     (s)TIMER:1                | 0000 |      1.799 ms |       117 |      0.055 ms |    3398385.568033 s |    3398385.568088 s |
>     (w)0xffff9c66e563ee98     | 0006 |      1.561 ms |         5 |      0.351 ms |    3398384.060021 s |    3398384.060371 s |

What units are used for "Frequency"? It would be helpful to include somewhere.

PC