Re: Database regression due to scheduler changes ?

From: Brian Twichell
Date: Mon Nov 14 2005 - 18:03:49 EST


Nick Piggin wrote:

Just one other thing - A couple of fields aren't actually getting
initialised at all, which I didn't pick up on.

This bug looks to have been due to a mismerge between the
common asm-powerpc directory and one of my scheduler changes
somewhere along the line.

If you get time to try this out, that would be great.

===================================================================
--- linux-2.6.orig/include/asm-powerpc/topology.h 2005-11-09 16:43:16.000000000 +1100
+++ linux-2.6/include/asm-powerpc/topology.h 2005-11-09 16:45:17.000000000 +1100
@@ -51,6 +51,10 @@ static inline int node_to_first_cpu(int .cache_hot_time = (10*1000000), \
.cache_nice_tries = 1, \
.per_cpu_gain = 100, \
+ .busy_idx = 3, \
+ .idle_id = 1, \
+ .newidle_idx = 2, \
+ .wake_idx = 1, \
.flags = SD_LOAD_BALANCE \
| SD_BALANCE_EXEC \
| SD_BALANCE_NEWIDLE \


Nick,

That patch eliminates the regression on 2.6.13-rc5. Thanks !!
We are currently evaluating it with other workloads.

It also gives a boost on 2.6.14, but unfortunately we are still 1%
regressed on 2.6.14. (The regression on 2.6.14 was larger than
the regression on 2.6.13-rc5.) We're trying to isolate the 2.6.14
regression now. I'll let you know if we isolate it to a
scheduler change.

Cheers,
Brian

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