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 10:49:06 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.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 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

jirka