linux-kernel - Re: [PATCH v11 1/3]: perf util: map data buffer for preserving collected data

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Date:   Mon, 8 Oct 2018 14:38:59 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 1/3]: perf util: map data buffer for preserving
 collected data

On Mon, Oct 08, 2018 at 03:03:18PM +0300, Alexey Budankov wrote:
> Hi,
> 
> On 08.10.2018 13:50, Jiri Olsa wrote:
> > On Mon, Oct 08, 2018 at 09:14:29AM +0300, Alexey Budankov wrote:
> <SNIP>
> >>  
> >> +#ifdef HAVE_AIO_SUPPORT
> >> +static void perf_mmap__aio_munmap(struct perf_mmap *map)
> >> +{
> >> +	if (map->data)
> >> +		zfree(&map->data);
> >> +}
> > 
> > if we really need to keep this optional for compilation,
> > please make it as single block with dummy functions
> > for when it's not compiled in, like:
> > 
> > #ifdef 
> > static void perf_mmap__aio_munmap(struct perf_mmap *map)
> > {
> > 	if (map->data)
> > 		zfree(&map->data);
> > }
> > #else
> > static void perf_mmap__aio_munmap(struct perf_mmap *map) { }
> > #endif
> 
> Ok.
> 
> > 
> > thanks,
> > jirka
> > 
> > 
> >> +#endif
> >> +
> >>  void perf_mmap__munmap(struct perf_mmap *map)
> >>  {
> >> +#ifdef HAVE_AIO_SUPPORT
> >> +	perf_mmap__aio_munmap(map);
> >> +#endif
> >>  	if (map->base != NULL) {
> >>  		munmap(map->base, perf_mmap__mmap_len(map));
> >>  		map->base = NULL;
> >> @@ -164,8 +175,40 @@ void perf_mmap__munmap(struct perf_mmap *map)
> >>  	auxtrace_mmap__munmap(&map->auxtrace_mmap);
> >>  }
> 
> Well, let's go with stub functions design as opposite to pure 
> conditional compilation. However this may, probably, result in 
> unintended Perf tool binary size growth, even if NO_AIO is 
> defined during compilation.

hum, empty functions are be optimized out

jirka