linux-kernel - Re: [PATCH v1] perf record: fix binding of AIO user space buffers to nodes

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Date:   Thu, 12 Mar 2020 11:31:52 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] perf record: fix binding of AIO user space buffers to
 nodes

Em Thu, Mar 12, 2020 at 03:21:45PM +0300, Alexey Budankov escreveu:
> 
> Correct maxnode parameter value passed to mbind() syscall to be
> the amount of node mask bits to analyze plus 1. Dynamically allocate
> node mask memory depending on the index of node of cpu being profiled.
> Fixes: c44a8b44ca9f ("perf record: Bind the AIO user space buffers to nodes")
> Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>
> ---
>  tools/perf/util/mmap.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index 3b664fa673a6..6d604cd67a95 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -98,20 +98,29 @@ static int perf_mmap__aio_bind(struct mmap *map, int idx, int cpu, int affinity)
>  {
>  	void *data;
>  	size_t mmap_len;
> -	unsigned long node_mask;
> +	unsigned long *node_mask;
> +	unsigned long node_index;
> +	int err = 0;
>  
>  	if (affinity != PERF_AFFINITY_SYS && cpu__max_node() > 1) {
>  		data = map->aio.data[idx];
>  		mmap_len = mmap__mmap_len(map);
> -		node_mask = 1UL << cpu__get_node(cpu);
> -		if (mbind(data, mmap_len, MPOL_BIND, &node_mask, 1, 0)) {
> -			pr_err("Failed to bind [%p-%p] AIO buffer to node %d: error %m\n",
> -				data, data + mmap_len, cpu__get_node(cpu));
> +		node_index = cpu__get_node(cpu);
> +		node_mask = bitmap_alloc(node_index + 1);
> +		if (!node_mask) {
> +			pr_err("Failed to allocate node mask for mbind: error %m\n");
>  			return -1;
>  		}
> +		set_bit(node_index, node_mask);
> +		if (mbind(data, mmap_len, MPOL_BIND, node_mask, node_index + 1 + 1/*nr_bits + 1*/, 0)) {

                                                                                  ^^^^^^^^^^^^^^
										  Leftover?

> +			pr_err("Failed to bind [%p-%p] AIO buffer to node %lu: error %m\n",
> +				data, data + mmap_len, node_index);
> +			err = -1;
> +		}
> +		bitmap_free(node_mask);
>  	}
>  
> -	return 0;
> +	return err;
>  }
>  #else /* !HAVE_LIBNUMA_SUPPORT */
>  static int perf_mmap__aio_alloc(struct mmap *map, int idx)
> -- 
> 2.24.1
> 

-- 

- Arnaldo