linux-kernel - Re: [PATCH v12 01/16] perf record: Introduce thread affinity and mmap masks

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Message-ID: <90352f48-86a8-f8d9-2b74-b884b32d013d@linux.intel.com>
Date:   Mon, 20 Dec 2021 13:37:48 +0300
From:   "Bayduraev, Alexey V" <alexey.v.bayduraev@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        Alexei Budankov <abudankov@...wei.com>,
        Riccardo Mancini <rickyman7@...il.com>
Subject: Re: [PATCH v12 01/16] perf record: Introduce thread affinity and mmap
 masks

On 05.12.2021 18:13, Jiri Olsa wrote:
> On Tue, Nov 23, 2021 at 05:07:57PM +0300, Alexey Bayduraev wrote:
> 
> SNIP
> 
>> +static void record__mmap_cpu_mask_init(struct mmap_cpu_mask *mask, struct perf_cpu_map *cpus)
>> +{
>> +	int c;
>> +
>> +	for (c = 0; c < cpus->nr; c++)
>> +		set_bit(cpus->map[c], mask->bits);
>> +}
>> +
>> +static void record__free_thread_masks(struct record *rec, int nr_threads)
>> +{
>> +	int t;
>> +
>> +	if (rec->thread_masks)
>> +		for (t = 0; t < nr_threads; t++)
>> +			record__thread_mask_free(&rec->thread_masks[t]);
>> +
>> +	zfree(&rec->thread_masks);
>> +}
>> +
>> +static int record__alloc_thread_masks(struct record *rec, int nr_threads, int nr_bits)
>> +{
>> +	int t, ret;
>> +
>> +	rec->thread_masks = zalloc(nr_threads * sizeof(*(rec->thread_masks)));
>> +	if (!rec->thread_masks) {
>> +		pr_err("Failed to allocate thread masks\n");
>> +		return -ENOMEM;
>> +	}
>> +
>> +	for (t = 0; t < nr_threads; t++) {
>> +		ret = record__thread_mask_alloc(&rec->thread_masks[t], nr_bits);
>> +		if (ret)
>> +			goto out_free;
>> +		record__thread_mask_clear(&rec->thread_masks[t]);
> 
> nit, is this clear needed?

Hi,

You are right, since all elements of mask->bits is set to zero after
bitmap_zalloc in record__thread_mask_alloc, calling
record__thread_mask_clear after record__thread_mask_alloc
is redundant.
I will remove it here and in [PATCH v12 13/16].

Thanks,
Alexey

> 
> jirka
> 
>> +	}
>> +
>> +	return 0;
>> +
>> +out_free:
>> +	record__free_thread_masks(rec, nr_threads);
>> +
>> +	return ret;
>> +}
>> +
> 
> SNIP
>