Re: kernbench on 512p
From: Manfred Spraul
Date: Tue Sep 14 2004 - 14:23:24 EST
Greg Edwards wrote:
| >
| Which value did you use for RCU_GROUP_SIZE? I'm not sure what's the
| optimal value for 512p - probably 32 or so.
I used what was defined in the patch
+#define RCU_GROUP_SIZE 2
I can try running with a couple different values and see how it looks.
Ok, that explains the lockstat: I've missed data on rcu_group_state.lock.
I'd just use 32. The code uses a two-level bitmap and the group size
specifies the size of the lower level.
Thus you use right now a 2/256 split. Therefore you still trash the
spinlock that protects the upper level. Group size 32 would generate a
32/16 split.
--
Manfred
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