lkml.org 
[lkml]   [2009]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] UV: cpu_relax in uv_wait_completion
From
Date

From: Cliff Wickman <cpw@sgi.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@sgi.com>
Acked-by: Jack Steiner <steiner@sgi.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;
}

\
 
 \ /
  Last update: 2009-01-15 16:53    [W:0.205 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site