[PATCH] drm/vmwgfx: Add tracepoints

[Ian Forbes]

On Thu, Sep 5, 2024 at 10:59 PM Zack Rusin <zack.rusin at broadcom.com> wrote:
>
>
> In general it looks good but what's the reason for the submit_time?
>
> z

So you can get an approximate time of how long each command buffer takes.
You can then use it to construct a histogram or look for outliers
using bpftrace.
Useful when doing performance analysis to determine if slowdowns are being
caused by the host or the guest driver.

$ sudo bpftrace -e 'tracepoint:vmwgfx:vmwgfx_cmdbuf_done{
if(args->status == 1) { $elapsed =(jiffies -
args->header->submit_time); @exec_times = hist($elapsed);  } }'
Attaching 1 probe...
^C

@exec_times:
[0]                   59 |@@@                                                 |
[1]                  334 |@@@@@@@@@@@@@@@@@@                                  |
[2, 4)               431 |@@@@@@@@@@@@@@@@@@@@@@@                             |
[4, 8)               961 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[8, 16)              596 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@                    |
[16, 32)             139 |@@@@@@@                                             |
[32, 64)              67 |@@@                                                 |
[64, 128)             36 |@                                                   |
[128, 256)            30 |@                                                   |
[256, 512)            17 |                                                    |