linux-kernel - Re: [PATCH v5 0/2] perf tools: add 'perf irq' to measure the hardware interrupts

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Date:   Thu, 25 Feb 2021 17:19:02 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Bixuan Cui <cuibixuan@...wei.com>
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        namhyung@...nel.org, linux-kernel@...r.kernel.org, hagen@...u.net,
        john.wanghui@...wei.com, abudankov@...wei.com, yz.yuzhou@...wei.com
Subject: Re: [PATCH v5 0/2] perf tools: add 'perf irq' to measure the
 hardware interrupts

On Thu, Feb 25, 2021 at 09:30:14AM +0800, Bixuan Cui wrote:
> When the hardware interrupt processing function is executed, the interrupt and 
> preemption of current cpu are disabled. As a result, the task is suspended.
> The execution of the hardware processing function takes a long time
> (for example 5 ms), will affect the task scheduling performance.
> 
> This patches provides the 'perf irq' command to trace and calculate the time
> consumed of the hardware irq function.
> 
> [verse]
> 'perf irq' [<options>] {record|report}
> 
> DESCRIPTION
> -----------
> There are several variants of 'perf irq':
> 
>   'perf irq record <command>' to record the irq handler events
>   of an arbitrary workload.
> 
>   'perf irq report' to calculate the time consumed by each
>    hardware interrupt processing function.
> 
>     Example usage:
>         perf irq record -- sleep 1
>         perf irq report
> 
>    By default it shows the individual irq events, including the irq name,
>    cpu(execute the hardware interrupt processing function), time consumed,
>    entry time and exit time for the each hardware irq:
> 
>    -------------------------------------------------------------------------------------------------------------------------------------------
>      Irq name         |  CPU   | Time consume us | Handler entry time | Handler exit time
>    -------------------------------------------------------------------------------------------------------------------------------------------
>      enp2s0f2-tx-0    | [0006] |      0.000001 s |   6631263.313329 s |   6631263.313330 s
>      megasas          | [0013] |      0.000003 s |   6631263.209564 s |   6631263.209567 s
>      acpi             | [0016] |      0.000018 s |   6631263.085787 s |   6631263.085805 s
> 
>     And:
> 	perf irq --cpu 78 record -- sleep 1
> 	perf irq --cpu 78 report
>    -------------------------------------------------------------------------------------------------------------------------------------------
>      Irq name         |  CPU   | Time consume us | Handler entry time | Handler exit time
>    -------------------------------------------------------------------------------------------------------------------------------------------
>     enp134s0f0-TxRx-2 | [0078] |      0.000005 s |    693757.533189 s |    693757.533194 s

hum, please yell at me if this was discussed before or I'm missing
something else, but wouldn't this be better and easier as a perf's
python script?

jirka

> 
> Changes from v5:
> * Resolve conflicts by the latest commit.
> 
> Changes from v4:
> * Keep pairs of irq entry/exit per cpu;
> * Add NUL-termination to the end of irq->irq_name when strncpy is used;
> * Delete some unused declarations and parameters;
> 
> Changes from v3:
> * Delete 'perf irq script' because its function can be implemented using
>   'perf script';
> * Add --cpu option for 'perf irq';
> 
> Changes from v2:
> * Delete "-m", "1024" in __cmd_record();
> * Change 'perf irq timeconsume <options>' to 'perf irq report <options>';
> * Fix a error for tools/perf/Documentation/perf-irq.txt;
> 
> Bixuan Cui (2):
>   perf tools: add 'perf irq' to measure the hardware interrupts
>   perf tools: Add documentation for 'perf irq' command
> 
>  tools/perf/Build                      |   1 +
>  tools/perf/Documentation/perf-irq.txt |  47 +++++
>  tools/perf/builtin-irq.c              | 260 ++++++++++++++++++++++++++
>  tools/perf/builtin.h                  |   1 +
>  tools/perf/command-list.txt           |   1 +
>  tools/perf/perf.c                     |   1 +
>  6 files changed, 311 insertions(+)
>  create mode 100644 tools/perf/Documentation/perf-irq.txt
>  create mode 100644 tools/perf/builtin-irq.c
> 
> -- 
> 2.17.1
>