linux-kernel - Re: [PATCH] perf bench numa: Fix assertion for nodes bitfield

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Date:	Mon, 21 Mar 2016 17:49:07 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Jakub Jelen <jakuje@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>, trivial@...nel.org,
	Jakub Jelen <jjelen@...hat.com>
Subject: Re: [PATCH] perf bench numa: Fix assertion for nodes bitfield

Em Sat, Mar 19, 2016 at 12:58:07PM +0100, Jakub Jelen escreveu:
> Comparing bits and bytes in numa benchmark assertion
> 
> I hit the issue on two socket Power8 machine presenting its numa nodes as
>  0,1,16,17 (according to numactl). Therefore I got error
>  (and hang of parent process):
> 
>     perf: bench/numa.c:296: bind_to_memnode: Assertion `!(g->p.nr_nodes > (int)sizeof(nodemask))' failed.
> 
> This is obviously false positive. We can fit all the 18 nodes into
> bitfield of 8 bytes (long on 64b architecture).
> 
> Signed-off-by: Jakub Jelen <jakuje@...il.com>
> ---
> Hello kernel list.
> This is my first patch for kernel, so if I missed some of the guidelines,
> please be patient :) I hope everything is explained in the commit message.

Very good start then, I saw no problems, you looked at existing
changesets (I guess), even capitalizing the first word after "perf bench
numa: "!  8-)

Looks fine, applied, thanks.

- Arnaldo
 
> Thanks,
> Jakub
> 
>  tools/perf/bench/numa.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/bench/numa.c b/tools/perf/bench/numa.c
> index 870b7e6..5276b24 100644
> --- a/tools/perf/bench/numa.c
> +++ b/tools/perf/bench/numa.c
> @@ -293,7 +293,7 @@ static void bind_to_memnode(int node)
>  	if (node == -1)
>  		return;
>  
> -	BUG_ON(g->p.nr_nodes > (int)sizeof(nodemask));
> +	BUG_ON(g->p.nr_nodes > (int)sizeof(nodemask)*8);
>  	nodemask = 1L << node;
>  
>  	ret = set_mempolicy(MPOL_BIND, &nodemask, sizeof(nodemask)*8);
> -- 
> 2.5.0