From: Peter Zijlstra <peterz@infradead.org>
To: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: mingo@redhat.com, acme@kernel.org, namhyung@kernel.org,
mark.rutland@arm.com, alexander.shishkin@linux.intel.com,
jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com,
kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v5 1/2] perf/core: Fix small negative period being ignored
Date: Mon, 2 Sep 2024 11:20:53 +0200 [thread overview]
Message-ID: <20240902092053.GC4723@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20240831074316.2106159-2-luogengkun@huaweicloud.com>
On Sat, Aug 31, 2024 at 07:43:15AM +0000, Luo Gengkun wrote:
> kernel/events/core.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index c973e3c11e03..a9395bbfd4aa 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -4092,7 +4092,11 @@ static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count, bo
> period = perf_calculate_period(event, nsec, count);
>
> delta = (s64)(period - hwc->sample_period);
> - delta = (delta + 7) / 8; /* low pass filter */
> + if (delta >= 0)
> + delta += 7;
> + else
> + delta -= 7;
> + delta /= 8; /* low pass filter */
>
> sample_period = hwc->sample_period + delta;
>
OK, that makes sense, Thanks!
next prev parent reply other threads:[~2024-09-02 9:21 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-31 7:43 [PATCH v5 0/2] Fix perf adjust period algorithm Luo Gengkun
2024-08-31 7:43 ` [PATCH v5 1/2] perf/core: Fix small negative period being ignored Luo Gengkun
2024-08-31 7:39 ` kernel test robot
2024-09-02 9:20 ` Peter Zijlstra [this message]
2024-09-05 15:03 ` [tip: perf/core] " tip-bot2 for Luo Gengkun
2024-08-31 7:43 ` [PATCH v5 2/2] perf/core: Fix incorrect time diff in tick adjust period Luo Gengkun
2024-09-02 9:50 ` Peter Zijlstra
2024-09-05 6:38 ` Luo Gengkun
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