Re: [PATCH v5 3/3] perf record: adapt affinity to machines with #CPUs > 1K

[Alexey Budankov]

On 04.12.2019 16:48, Arnaldo Carvalho de Melo wrote:
> Em Tue, Dec 03, 2019 at 02:45:27PM +0300, Alexey Budankov escreveu:
>>
>> Use struct mmap_cpu_mask type for tool's thread and mmap data
>> buffers to overcome current 1024 CPUs mask size limitation of
>> cpu_set_t type.
>>
>> Currently glibc cpu_set_t type has internal mask size limit
>> of 1024 CPUs. Moving to struct mmap_cpu_mask type allows
>> overcoming that limit. tools bitmap API is used to manipulate
>> objects of struct mmap_cpu_mask type.
> 
> Had to apply this to fix the build in some toolchains/arches:
> 
> [acme@quaco perf]$ git diff
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 7bc83755ef8c..4c301466101b 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -2508,10 +2508,10 @@ int cmd_record(int argc, const char **argv)
>                 rec->affinity_mask.nbits = cpu__max_cpu();
>                 rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
>                 if (!rec->affinity_mask.bits) {
> -                       pr_err("Failed to allocate thread mask for %ld cpus\n", rec->affinity_mask.nbits);
> +                       pr_err("Failed to allocate thread mask for %zd cpus\n", rec->affinity_mask.nbits);
>                         return -ENOMEM;
>                 }
> -               pr_debug2("thread mask[%ld]: empty\n", rec->affinity_mask.nbits);
> +               pr_debug2("thread mask[%zd]: empty\n", rec->affinity_mask.nbits);
>         }
> 
>         err = record__auxtrace_init(rec);

Thank you.

~Alexey

> 
> 
>  
>> Reported-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
>> Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
>> ---
>>  tools/perf/builtin-record.c | 28 ++++++++++++++++++++++------
>>  tools/perf/util/mmap.c      | 28 ++++++++++++++++++++++------
>>  tools/perf/util/mmap.h      |  2 +-
>>  3 files changed, 45 insertions(+), 13 deletions(-)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index fb19ef63cc35..7bc83755ef8c 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -62,6 +62,7 @@
>>  #include <linux/string.h>
>>  #include <linux/time64.h>
>>  #include <linux/zalloc.h>
>> +#include <linux/bitmap.h>
>>  
>>  struct switch_output {
>>  	bool		 enabled;
>> @@ -93,7 +94,7 @@ struct record {
>>  	bool			timestamp_boundary;
>>  	struct switch_output	switch_output;
>>  	unsigned long long	samples;
>> -	cpu_set_t		affinity_mask;
>> +	struct mmap_cpu_mask	affinity_mask;
>>  	unsigned long		output_max_size;	/* = 0: unlimited */
>>  };
>>  
>> @@ -961,10 +962,15 @@ static struct perf_event_header finished_round_event = {
>>  static void record__adjust_affinity(struct record *rec, struct mmap *map)
>>  {
>>  	if (rec->opts.affinity != PERF_AFFINITY_SYS &&
>> -	    !CPU_EQUAL(&rec->affinity_mask, &map->affinity_mask)) {
>> -		CPU_ZERO(&rec->affinity_mask);
>> -		CPU_OR(&rec->affinity_mask, &rec->affinity_mask, &map->affinity_mask);
>> -		sched_setaffinity(0, sizeof(rec->affinity_mask), &rec->affinity_mask);
>> +	    !bitmap_equal(rec->affinity_mask.bits, map->affinity_mask.bits,
>> +			  rec->affinity_mask.nbits)) {
>> +		bitmap_zero(rec->affinity_mask.bits, rec->affinity_mask.nbits);
>> +		bitmap_or(rec->affinity_mask.bits, rec->affinity_mask.bits,
>> +			  map->affinity_mask.bits, rec->affinity_mask.nbits);
>> +		sched_setaffinity(0, MMAP_CPU_MASK_BYTES(&rec->affinity_mask),
>> +				  (cpu_set_t *)rec->affinity_mask.bits);
>> +		if (verbose == 2)
>> +			mmap_cpu_mask__scnprintf(&rec->affinity_mask, "thread");
>>  	}
>>  }
>>  
>> @@ -2433,7 +2439,6 @@ int cmd_record(int argc, const char **argv)
>>  # undef REASON
>>  #endif
>>  
>> -	CPU_ZERO(&rec->affinity_mask);
>>  	rec->opts.affinity = PERF_AFFINITY_SYS;
>>  
>>  	rec->evlist = evlist__new();
>> @@ -2499,6 +2504,16 @@ int cmd_record(int argc, const char **argv)
>>  
>>  	symbol__init(NULL);
>>  
>> +	if (rec->opts.affinity != PERF_AFFINITY_SYS) {
>> +		rec->affinity_mask.nbits = cpu__max_cpu();
>> +		rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
>> +		if (!rec->affinity_mask.bits) {
>> +			pr_err("Failed to allocate thread mask for %ld cpus\n", rec->affinity_mask.nbits);
>> +			return -ENOMEM;
>> +		}
>> +		pr_debug2("thread mask[%ld]: empty\n", rec->affinity_mask.nbits);
>> +	}
>> +
>>  	err = record__auxtrace_init(rec);
>>  	if (err)
>>  		goto out;
>> @@ -2613,6 +2628,7 @@ int cmd_record(int argc, const char **argv)
>>  
>>  	err = __cmd_record(&record, argc, argv);
>>  out:
>> +	bitmap_free(rec->affinity_mask.bits);
>>  	evlist__delete(rec->evlist);
>>  	symbol__exit();
>>  	auxtrace_record__free(rec->itr);
>> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
>> index 43c12b4a3e17..832d2cb94b2c 100644
>> --- a/tools/perf/util/mmap.c
>> +++ b/tools/perf/util/mmap.c
>> @@ -219,6 +219,8 @@ static void perf_mmap__aio_munmap(struct mmap *map __maybe_unused)
>>  
>>  void mmap__munmap(struct mmap *map)
>>  {
>> +	bitmap_free(map->affinity_mask.bits);
>> +
>>  	perf_mmap__aio_munmap(map);
>>  	if (map->data != NULL) {
>>  		munmap(map->data, mmap__mmap_len(map));
>> @@ -227,7 +229,7 @@ void mmap__munmap(struct mmap *map)
>>  	auxtrace_mmap__munmap(&map->auxtrace_mmap);
>>  }
>>  
>> -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;
>> +
>>  	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
>>  		build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
>>  	else if (mp->affinity == PERF_AFFINITY_CPU)
>> -		CPU_SET(map->core.cpu, &map->affinity_mask);
>> +		set_bit(map->core.cpu, map->affinity_mask.bits);
>> +
>> +	return 0;
>>  }
>>  
>>  int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
>> @@ -261,7 +269,15 @@ int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
>>  		return -1;
>>  	}
>>  
>> -	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;
>> +	}
>> +
>> +	if (verbose == 2)
>> +		mmap_cpu_mask__scnprintf(&map->affinity_mask, "mmap");
>>  
>>  	map->core.flush = mp->flush;
>>  
>> diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
>> index ef51667fabcb..9d5f589f02ae 100644
>> --- a/tools/perf/util/mmap.h
>> +++ b/tools/perf/util/mmap.h
>> @@ -40,7 +40,7 @@ struct mmap {
>>  		int		 nr_cblocks;
>>  	} aio;
>>  #endif
>> -	cpu_set_t	affinity_mask;
>> +	struct mmap_cpu_mask	affinity_mask;
>>  	void		*data;
>>  	int		comp_level;
>>  };
>> -- 
>> 2.20.1
>>
>