From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH v2 1/2]: perf util: map data buffer for preserving
 collected data
Date: Mon, 27 Aug 2018 10:33:03 +0200
Message-ID: <20180827083303.GD24695@krava>
References: <e92805d0-3338-2ce5-5e88-369d406fe0a7@linux.intel.com>
 <e5591d27-5386-1d41-b09b-421316f75d07@linux.intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <linux-kernel-owner@vger.kernel.org>
Content-Disposition: inline
In-Reply-To: <e5591d27-5386-1d41-b09b-421316f75d07@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
To: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>, Arnaldo Carvalho de Melo <acme@kernel.org>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, Namhyung Kim <namhyung@kernel.org>, Andi Kleen <ak@linux.intel.com>, linux-kernel <linux-kernel@vger.kernel.org>, linux-perf-users@vger.kernel.org
List-Id: linux-perf-users.vger.kernel.org

On Thu, Aug 23, 2018 at 07:42:09PM +0300, Alexey Budankov wrote:

SNIP

> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index fc832676a798..e71d46cb01cc 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -155,6 +155,10 @@ void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __mayb
>  
>  void perf_mmap__munmap(struct perf_mmap *map)
>  {
> +	if (map->data != NULL) {
> +		munmap(map->data, perf_mmap__mmap_len(map));
> +		map->data = NULL;
> +	}
>  	if (map->base != NULL) {
>  		munmap(map->base, perf_mmap__mmap_len(map));
>  		map->base = NULL;
> @@ -190,6 +194,14 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
>  		map->base = NULL;
>  		return -1;
>  	}
> +	map->data = mmap(NULL, perf_mmap__mmap_len(map), PROT_READ | PROT_WRITE,
> +			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

hum, why does map->data need to be mmap-ed?

jirka