Re: [PATCH v4 4/5] perf stat: Enable iostat mode for x86 platforms

[liuqi (BA)]

Hi Alexander,

On 2021/2/3 21:58, Alexander Antonov wrote:
> This functionality is based on recently introduced sysfs attributes
> for Intel® Xeon® Scalable processor family (code name Skylake-SP):
> Commit bb42b3d39781 ("perf/x86/intel/uncore: Expose an Uncore unit to
> IIO PMON mapping")
>
> Mode is intended to provide four I/O performance metrics in MB per each
> PCIe root port:
>   - Inbound Read: I/O devices below root port read from the host memory
>   - Inbound Write: I/O devices below root port write to the host memory
>   - Outbound Read: CPU reads from I/O devices below root port
>   - Outbound Write: CPU writes to I/O devices below root port
>
> Each metric requiries only one uncore event which increments at every 4B
> transfer in corresponding direction. The formulas to compute metrics
> are generic:
>      #EventCount * 4B / (1024 * 1024)
>
> Signed-off-by: Alexander Antonov<alexander.antonov@xxxxxxxxxxxxxxx>
> ---
>   tools/perf/Documentation/perf-iostat.txt |  88 ++++++
>   tools/perf/Makefile.perf                 |   5 +-
>   tools/perf/arch/x86/util/Build           |   1 +
>   tools/perf/arch/x86/util/iostat.c        | 345 +++++++++++++++++++++++
>   tools/perf/command-list.txt              |   1 +
>   tools/perf/perf-iostat.sh                |  12 +
>   6 files changed, 451 insertions(+), 1 deletion(-)
>   create mode 100644 tools/perf/Documentation/perf-iostat.txt
>   create mode 100644 tools/perf/perf-iostat.sh
>
> diff --git a/tools/perf/Documentation/perf-iostat.txt b/tools/perf/Documentation/perf-iostat.txt
> new file mode 100644
> index 000000000000..165176944031
> --- /dev/null
> +++ b/tools/perf/Documentation/perf-iostat.txt
> @@ -0,0 +1,88 @@
> +perf-iostat(1)
> +===============
> +
> +NAME
> +----
> +perf-iostat - Show I/O performance metrics
> +
> +SYNOPSIS
> +--------
> +[verse]
> +'perf iostat' list
> +'perf iostat' <ports> -- <command> [<options>]
> +
> +DESCRIPTION
> +-----------
> +Mode is intended to provide four I/O performance metrics per each PCIe root port:
> +
> +- Inbound Read   - I/O devices below root port read from the host memory, in MB
> +
> +- Inbound Write  - I/O devices below root port write to the host memory, in MB
> +
> +- Outbound Read  - CPU reads from I/O devices below root port, in MB
> +
> +- Outbound Write - CPU writes to I/O devices below root port, in MB
> +
> +OPTIONS
> +-------
> +<command>...::
> +	Any command you can specify in a shell.
> +
> +list::
> +	List all PCIe root ports.

I noticed that "iostat" commond and cmd_iostat() callback function is 
not registered in cmd_struct in perf.c. So I think "perf iostat list" 
perhaps can not work properly.

I also test this patchset on x86 platform, and here is the log:

root@ubuntu:/home/lq# ./perf iostat list
perf: 'iostat' is not a perf-command. See 'perf --help'.
root@ubuntu:/home/lq# ./perf stat --iostat
^C
 Performance counter stats for 'system wide':

   port             Inbound Read(MB)    Inbound Write(MB)    Outbound 
Read(MB)   Outbound Write(MB)
0000:00                    0                    0                    0 
                 0
0000:80                    0                    0                    0 
                 0
0000:17                    0                    0                    0 
                 0
0000:85                    0                    0                    0 
                 0
0000:3a                    0                    0                    0 
                 0
0000:ae                    0                    0                    0 
                 0
0000:5d                    0                    0                    0 
                 0
0000:d7                    0                    0                    0 
                 0

       0.611303832 seconds time elapsed


root@ubuntu:/home/lq# ./perf stat --iostat=0000:17
^C
 Performance counter stats for 'system wide':

   port             Inbound Read(MB)    Inbound Write(MB)    Outbound 
Read(MB)   Outbound Write(MB)
0000:17                    0                    0                    0 
                 0

       0.521317572 seconds time elapsed

So how does following perf iostat list work, did I miss something?

Thanks,
Qi

> +
> +<ports>::
> +	Select the root ports for monitoring. Comma-separated list is supported.
> +
> +EXAMPLES
> +--------
> +
> +1. List all PCIe root ports (example for 2-S platform):
> +
> +   $ perf iostat list
> +   S0-uncore_iio_0<0000:00>
> +   S1-uncore_iio_0<0000:80>
> +   S0-uncore_iio_1<0000:17>
> +   S1-uncore_iio_1<0000:85>
> +   S0-uncore_iio_2<0000:3a>
> +   S1-uncore_iio_2<0000:ae>
> +   S0-uncore_iio_3<0000:5d>
> +   S1-uncore_iio_3<0000:d7>