linux-kernel - Re: [PATCH v6 1/3] perf/core: use rb trees for pinned/flexible groups

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Date:   Wed, 30 Aug 2017 14:13:11 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Kan Liang <kan.liang@...el.com>,
        Dmitri Prokhorov <Dmitry.Prohorov@...el.com>,
        Valery Cherepennikov <valery.cherepennikov@...el.com>,
        Mark Rutland <mark.rutland@....com>,
        Stephane Eranian <eranian@...gle.com>,
        David Carrillo-Cisneros <davidcc@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 1/3] perf/core: use rb trees for pinned/flexible groups

Alexey Budankov <alexey.budankov@...ux.intel.com> writes:

> On 30.08.2017 13:18, Alexander Shishkin wrote:
>> Alexey Budankov <alexey.budankov@...ux.intel.com> writes:
>> 
>>>>> Iterating cpu specific subtree like this:
>>>>>
>>>>> #define for_each_group_event(event, group, cpu, pmu, field)	 \
>>>>> 	for (event = rb_entry_safe(group_first(group, cpu, pmu), \
>>>>> 				   typeof(*event), field);	 \
>>>>> 	     event && event->cpu == cpu && event->pmu == pmu;	 \
>>>>> 	     event = rb_entry_safe(rb_next(&event->field),	 \
>>>>> 				   typeof(*event), field))
>>>>
>>>> Afaict, this assumes that you are also ordering on event->pmu, which
>>>> should be reflected in your _less function. And also assuming that
>>>> group_first() is doing the right thing. Can we see the code?
>>>
>>> I didn't do ordering by PMU for this patch set. Yet more I implemented 
>>> groups_first() like this:
>> 
>> Your iterator (quoted above) begs to differ.
>
> What do you specifically mean? I am doing iterations like this:

I mean the code that you've shown before, which is quoted above. It's
difficult to tell why something's not working if you don't show the
code.

Regards,
--
Alex