linux-kernel - Re: [PATCH v2 2/4] perf record: implement -z=<level> and --mmap-flush=<thres> options

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Date:   Thu, 21 Feb 2019 14:24:47 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] perf record: implement -z=<level> and
 --mmap-flush=<thres> options


On 21.02.2019 12:49, Jiri Olsa wrote:
> On Wed, Feb 20, 2019 at 06:24:30PM +0300, Alexey Budankov wrote:
>>
>> On 12.02.2019 16:08, Jiri Olsa wrote:
>>> On Mon, Feb 11, 2019 at 11:22:38PM +0300, Alexey Budankov wrote:
>>>
>>> SNIP
>>>
>>>> +static int perf_mmap__aio_mmap_blocks(struct perf_mmap *map);
>>>> +
>>>>  static int perf_mmap__aio_mmap(struct perf_mmap *map, struct mmap_params *mp)
>>>>  {
>>>> -	int delta_max, i, prio, ret;
>>>> +	int i, ret = 0, init_blocks = 1;
>>>>  
>>>>  	map->aio.nr_cblocks = mp->nr_cblocks;
>>>> +	if (map->aio.nr_cblocks == -1) {
>>>> +		map->aio.nr_cblocks = 1;
>>>> +		init_blocks = 0;
>>>> +	}
>>>> +
>>>>  	if (map->aio.nr_cblocks) {
>>>> -		map->aio.aiocb = calloc(map->aio.nr_cblocks, sizeof(struct aiocb *));
>>>> -		if (!map->aio.aiocb) {
>>>> -			pr_debug2("failed to allocate aiocb for data buffer, error %m\n");
>>>> -			return -1;
>>>> -		}
>>>> -		map->aio.cblocks = calloc(map->aio.nr_cblocks, sizeof(struct aiocb));
>>>> -		if (!map->aio.cblocks) {
>>>> -			pr_debug2("failed to allocate cblocks for data buffer, error %m\n");
>>>> -			return -1;
>>>> -		}
>>>>  		map->aio.data = calloc(map->aio.nr_cblocks, sizeof(void *));
>>>>  		if (!map->aio.data) {
>>>>  			pr_debug2("failed to allocate data buffer, error %m\n");
>>>>  			return -1;
>>>>  		}
>>>> -		delta_max = sysconf(_SC_AIO_PRIO_DELTA_MAX);
>>>>  		for (i = 0; i < map->aio.nr_cblocks; ++i) {
>>>>  			ret = perf_mmap__aio_alloc(map, i);
>>>>  			if (ret == -1) {
>>>> @@ -251,29 +245,16 @@ static int perf_mmap__aio_mmap(struct perf_mmap *map, struct mmap_params *mp)
>>>>  			ret = perf_mmap__aio_bind(map, i, map->cpu, mp->affinity);
>>>>  			if (ret == -1)
>>>>  				return -1;
>>>> -			/*
>>>> -			 * Use cblock.aio_fildes value different from -1
>>>> -			 * to denote started aio write operation on the
>>>> -			 * cblock so it requires explicit record__aio_sync()
>>>> -			 * call prior the cblock may be reused again.
>>>> -			 */
>>>> -			map->aio.cblocks[i].aio_fildes = -1;
>>>> -			/*
>>>> -			 * Allocate cblocks with priority delta to have
>>>> -			 * faster aio write system calls because queued requests
>>>> -			 * are kept in separate per-prio queues and adding
>>>> -			 * a new request will iterate thru shorter per-prio
>>>> -			 * list. Blocks with numbers higher than
>>>> -			 *  _SC_AIO_PRIO_DELTA_MAX go with priority 0.
>>>> -			 */
>>>> -			prio = delta_max - i;
>>>> -			map->aio.cblocks[i].aio_reqprio = prio >= 0 ? prio : 0;
>>>>  		}
>>>> +		if (init_blocks)
>>>> +			ret = perf_mmap__aio_mmap_blocks(map);
>>>>  	}
>>>>  
>>>> -	return 0;
>>>> +	return ret;
>>>>  }
>>>
>>> SNIP
>>>
>>> it seems like little refactoring happened in here (up and down) for
>>> aio code, which is not explained and I'm unable to follow it.. please
>>> separate this in simple change
>>
>> AIO buffers management has been taken out of HAVE_AIO_SUPPORT define
>> to be used for compression in case of serial streaming. It will be 
>> revisited after other issues are addressed.
> 
> as I said earlier, please separate this from aio

Ok.

Thanks,
Alexey


> 
> jirka
>