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Message-Id: <E1LNUV6-00025f-Q7@eag09.americas.sgi.com>
Date: Thu, 15 Jan 2009 09:51:20 -0600
From: Cliff Wickman <cpw@....com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...e.hu
Subject: [PATCH] UV: cpu_relax in uv_wait_completion
From: Cliff Wickman <cpw@....com>
The function uv_wait_completion() spins on reads of a memory-mapped
register, waiting for completion of BAU hardware replies.
It should call "cpu_relax()" between those reads to improve performance
on hyperthreaded configurations.
Signed-off-by: Cliff Wickman <cpw@....com>
Acked-by: Jack Steiner <steiner@....org>
---
arch/x86/kernel/tlb_uv.c | 1 +
1 file changed, 1 insertion(+)
Index: linux/arch/x86/kernel/tlb_uv.c
===================================================================
--- linux.orig/arch/x86/kernel/tlb_uv.c
+++ linux/arch/x86/kernel/tlb_uv.c
@@ -200,6 +200,7 @@ static int uv_wait_completion(struct bau
destination_timeouts = 0;
}
}
+ cpu_relax();
}
return FLUSH_COMPLETE;
}
--
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