linux-kernel - Re: [PATCH v4 3/3] perf record: adapt affinity to machines with #CPUs

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Message-ID: <cc0dd7dc-400f-7097-b371-e895c016aaae@linux.intel.com>
Date:   Tue, 3 Dec 2019 13:48:05 +0300
From:   Alexey Budankov <alexey.budankov@...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>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/3] perf record: adapt affinity to machines with #CPUs
 > 1K



On 03.12.2019 13:12, Jiri Olsa wrote:
> On Mon, Dec 02, 2019 at 09:58:48AM +0300, Alexey Budankov wrote:
> 
> SNIP
> 
>>  
>> -static void build_node_mask(int node, cpu_set_t *mask)
>> +static void build_node_mask(int node, struct mmap_cpu_mask *mask)
>>  {
>>  	int c, cpu, nr_cpus;
>>  	const struct perf_cpu_map *cpu_map = NULL;
>> @@ -240,17 +242,23 @@ static void build_node_mask(int node, cpu_set_t *mask)
>>  	for (c = 0; c < nr_cpus; c++) {
>>  		cpu = cpu_map->map[c]; /* map c index to online cpu index */
>>  		if (cpu__get_node(cpu) == node)
>> -			CPU_SET(cpu, mask);
>> +			set_bit(cpu, mask->bits);
>>  	}
>>  }
>>  
>> -static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>> +static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>>  {
>> -	CPU_ZERO(&map->affinity_mask);
>> +	map->affinity_mask.nbits = cpu__max_cpu();
>> +	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
>> +	if (!map->affinity_mask.bits)
>> +		return -1;
> 
> hum, this one should be also behind (rec->opts.affinity != PERF_AFFINITY_SYS)
> condition, right? sry I haven't noticed that before..

That has not been so far, but, probably like this:

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 7f573f646431..832d2cb94b2c 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -269,7 +269,8 @@ int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
                return -1;
        }
 
-       if (perf_mmap__setup_affinity_mask(map, mp)) {
+       if (mp->affinity != PERF_AFFINITY_SYS &&
+               perf_mmap__setup_affinity_mask(map, mp)) {
                pr_debug2("failed to alloc mmap affinity mask, error %d\n",
                          errno);
                return -1;

Thanks,
Alexey