Hi Lionel,
Thanks for your suggestions. I will send the patch to igt-dev@xxxxxxxxxxxxxxxxxxxxx.
This patch is regarding the git lab issue #1542. Based on the ftrace, a 2ms hrtimer results in around 5000 calls to read (because test duration is 10s). Based on average read times (30us), the total kernel_ns is larger than the value being compared and this fix is to allow user to have a larger timer value than the default 5ms to avoid waking up too frequently.
Thanks and Regards
Sowmya
-----Original Message-----
From: Landwerlin, Lionel G <lionel.g.landwerlin@xxxxxxxxx>
Sent: 27 August 2020 13:20
To: Kaparthi, SowmyaX <sowmyax.kaparthi@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Nerlige Ramappa, Umesh <umesh.nerlige.ramappa@xxxxxxxxx>
Subject: Re: [i-g-t] Fixing the latency of hrtimer
Hi Sowmya,
Thanks for the patch. If you could send it to the igt-dev@xxxxxxxxxxxxxxxxxxxxx list instead, this is where the IGT patches go.
Could you refresh my memory as to what this is fixing?
It sounds like this is just adjusting a value to match more common settings.
Cheers,
-Lionel
On 27/08/2020 10:38, Sowmya Kaparthi wrote:
> The blocking/polling parameterized tests were introduced to test
> different hrtimer configurations.These tests check how many times the
> process wakes up to read the reports with different hrtimer values (=
> duration of test / hrtimer value). A user is more likely to choose a
> larger hrtimer value than the default 5ms to avoid wake up too frequently.
>
> Cc: Landwerlin, Lionel G <lionel.g.landwerlin@xxxxxxxxx>
> Signed-off-by: Sowmya Kaparthi <sowmyax.kaparthi@xxxxxxxxx>
> ---
> tests/i915/perf.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tests/i915/perf.c b/tests/i915/perf.c index
> a894fd38..5fd1193f 100644
> --- a/tests/i915/perf.c
> +++ b/tests/i915/perf.c
> @@ -4995,7 +4995,7 @@ igt_main
> 40 * 1000 * 1000 /* default 40ms hrtimer */);
> test_blocking(500 * 1000 /* 500us oa period */,
> true /* set_kernel_hrtimer */,
> - 2 * 1000 * 1000 /* default 2ms hrtimer */);
> + 10 * 1000 * 1000 /* default 10ms hrtimer */);
> }
>
> igt_describe("Test polled read with default hrtimer frequency"); @@
> -5014,7 +5014,7 @@ igt_main
> 40 * 1000 * 1000 /* default 40ms hrtimer */);
> test_polling(500 * 1000 /* 500us oa period */,
> true /* set_kernel_hrtimer */,
> - 2 * 1000 * 1000 /* default 2ms hrtimer */);
> + 10 * 1000 * 1000 /* default 10ms hrtimer */);
> }
>
> igt_describe("Test polled read with buffer size smaller than
> available data");
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