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 10:47:49 +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 05:15:13PM +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
> > 
> >> -	if (rec->opts.nr_cblocks > nr_cblocks_max)
> >> -		rec->opts.nr_cblocks = nr_cblocks_max;
> >> -	if (verbose > 0)
> >> -		pr_info("nr_cblocks: %d\n", rec->opts.nr_cblocks);
> >> +	if (rec->opts.comp_level > 22)
> >> +		rec->opts.comp_level = 0;
> >> +	if (record__comp_enabled(rec) && !rec->opts.nr_cblocks) {
> >> +		 /*
> >> +		  * Allocate aio.data[0] buffer for compression.
> >> +		  */
> >> +		rec->opts.nr_cblocks = -1;
> >> +	}
> > 
> > I assume you're using aio.data[0] as a buffer for non-aio case
> > as compression buffer.. if that's the case, please dont do that
> > and use separate buffer for that
> 
> Do you want it to be one more field in the mmap struct or 
> aio related fields still could be reworked?

I dont like it to use aio buffers if it's generic feature,
so please add new pointer for the needed buffer

jirka