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Message-ID: <91cb7bea-3bec-b40c-24a2-be9052a30937@huawei.com>
Date: Mon, 4 Sep 2023 19:46:02 +0800
From: Yang Jihong <yangjihong1@...wei.com>
To: Ian Rogers <irogers@...gle.com>
CC: <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
<mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
<jolsa@...nel.org>, <namhyung@...nel.org>,
<adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>,
<sandipan.das@....com>, <ravi.bangoria@....com>,
<linux-kernel@...r.kernel.org>, <linux-perf-users@...r.kernel.org>
Subject: Re: [RFC v1 05/16] perf kwork: Overwrite original atom in the list
when a new atom is pushed.
Hello,
On 2023/9/4 12:13, Ian Rogers wrote:
> On Sat, Aug 12, 2023 at 1:52 AM Yang Jihong <yangjihong1@...wei.com> wrote:
>>
>> work_push_atom() supports nesting. Currently, all supported kworks are not
>> nested. A `overwrite` parameter is added to overwrite the original atom in
>> the list.
>>
>> Signed-off-by: Yang Jihong <yangjihong1@...wei.com>
>> ---
>> tools/perf/builtin-kwork.c | 24 ++++++++++++++++++------
>> 1 file changed, 18 insertions(+), 6 deletions(-)
>>
>> diff --git a/tools/perf/builtin-kwork.c b/tools/perf/builtin-kwork.c
>> index 42ea59a957ae..f620911a26a2 100644
>> --- a/tools/perf/builtin-kwork.c
>> +++ b/tools/perf/builtin-kwork.c
>> @@ -392,9 +392,10 @@ static int work_push_atom(struct perf_kwork *kwork,
>> struct evsel *evsel,
>> struct perf_sample *sample,
>> struct machine *machine,
>> - struct kwork_work **ret_work)
>> + struct kwork_work **ret_work,
>> + bool overwrite)
>
> kerneldoc would be useful. Pushing something seems self-evident but
> what does overwrite mean without reading the code?
Okay, I'll add comments.
>
>> {
>> - struct kwork_atom *atom, *dst_atom;
>> + struct kwork_atom *atom, *dst_atom, *last_atom;
>> struct kwork_work *work, key;
>>
>> BUG_ON(class->work_init == NULL);
>> @@ -427,6 +428,17 @@ static int work_push_atom(struct perf_kwork *kwork,
>> if (ret_work != NULL)
>> *ret_work = work;
>>
>> + if (overwrite) {
>> + last_atom = list_last_entry_or_null(&work->atom_list[src_type],
>> + struct kwork_atom, list);
>> + if (last_atom) {
>> + atom_del(last_atom);
>> +
>> + kwork->nr_skipped_events[src_type]++;
>> + kwork->nr_skipped_events[KWORK_TRACE_MAX]++;
>> + }
>> + }
>> +
>> list_add_tail(&atom->list, &work->atom_list[src_type]);
>>
>> return 0;
>> @@ -502,7 +514,7 @@ static int report_entry_event(struct perf_kwork *kwork,
>> {
>> return work_push_atom(kwork, class, KWORK_TRACE_ENTRY,
>> KWORK_TRACE_MAX, evsel, sample,
>> - machine, NULL);
>> + machine, NULL, true);
>
> nit: for constant arguments it can be useful to add parameter names
> which can enable checks like clang-tidy's bugprone argument:
> https://clang.llvm.org/extra/clang-tidy/checks/bugprone/argument-comment.html
> This would make this:
> return work_push_atom(kwork, class, KWORK_TRACE_ENTRY,
> KWORK_TRACE_MAX, evsel, sample,
> machine, /*ret_work=*/NULL, /*overwite=*/true);
>
Thanks for your advice, will add parameter names later.
Thanks,
Yang
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