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

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Message-ID: <3e12075b-88e1-81e0-3b8a-6467ddc32475@linux.intel.com>
Date:   Mon, 25 Feb 2019 18:27:05 +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 14:24, Alexey Budankov wrote:
> 
> 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.

Addressed.

> 
> Thanks,
> Alexey
> 
> 
>>
>> jirka
>>
>