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From: Dave Hansen <dave@sr71.net>
To: linux-kernel@vger.kernel.org
Cc: Dave Hansen <dave@sr71.net>,
	dave.hansen@linux.intel.com, akpm@linux-foundation.org,
	peterz@infradead.org, mingo@kernel.org
Subject: [PATCH] x86, sched: fix up typo in topology detection
Date: Tue, 30 Sep 2014 14:45:46 -0700	[thread overview]
Message-ID: <20140930214546.FD481CFF@viggo.jf.intel.com> (raw)


From: Dave Hansen <dave.hansen@linux.intel.com>

Commit cebf15eb09 (in linux-next now) added some code to try to
detect the situation where we have a NUMA node inside of the
"DIE" sched domain.  It detected this by looking for cpus which
match_die() but do not match NUMA nodes via topology_same_node().

I wrote it up as:

	if (match_die(c, o) == !topology_same_node(c, o))

which actually seemed to work some of the time, albiet
accidentally.

It should have been doing an &&, not an ==.

This code essentially chopped off the "DIE" domain on one of
Andrew Morton's systems.  He reported that this patch fixed his
issue.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
---

 b/arch/x86/kernel/smpboot.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN arch/x86/kernel/smpboot.c~fix-up-typo arch/x86/kernel/smpboot.c
--- a/arch/x86/kernel/smpboot.c~fix-up-typo	2014-09-30 14:24:52.934235516 -0700
+++ b/arch/x86/kernel/smpboot.c	2014-09-30 14:30:42.074917876 -0700
@@ -445,7 +445,7 @@ void set_cpu_sibling_map(int cpu)
 			} else if (i != cpu && !c->booted_cores)
 				c->booted_cores = cpu_data(i).booted_cores;
 		}
-		if (match_die(c, o) == !topology_same_node(c, o))
+		if (match_die(c, o) && !topology_same_node(c, o))
 			primarily_use_numa_for_topology();
 	}
 }
_

             reply	other threads:[~2014-09-30 21:46 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-30 21:45 Dave Hansen [this message]
2014-10-03  5:27 ` [tip:sched/core] sched/x86: Fix up typo in topology detection tip-bot for Dave Hansen

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