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From: steiner on 19 Jul 2010 17:40
From: Jack Steiner <steiner(a)sgi.com>

In some cases, for performance reasons flushing the SGI GRU cbe
needs to dirty the cacheline before doing the cacheline flush. This ensures
that the dirty cacheline actually goes back to the caching home agent.
Update a reserved field in the CBE instead of a field that might be used. This
_should_ not be required (dirtying any field should be ok) but early
silicon has an issue here.

Note that flushing the CL is not a requirement - only a performance enhancement.

Signed-off-by: Jack Steiner <steiner(a)sgi.com>


---
drivers/misc/sgi-gru/grufault.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/drivers/misc/sgi-gru/grufault.c
===================================================================
--- linux.orig/drivers/misc/sgi-gru/grufault.c 2010-06-09 08:11:40.285085853 -0500
+++ linux/drivers/misc/sgi-gru/grufault.c 2010-06-09 08:11:41.157110138 -0500
@@ -306,7 +306,7 @@ upm:
static void gru_flush_cache_cbe(struct gru_control_block_extended *cbe)
{
if (unlikely(cbe)) {
- cbe->cbrexecstatus = 0; /* make CL dirty */
+ cbe->reserved6 = 0; /* make CL dirty */
gru_flush_cache(cbe);
}
}

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Prev: [Patch 08/25] GRU - flush gru tlb when driver is loaded
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