Re: kernbench on 512p

Manfred Spraul
2004-09-14T19:19:04Z

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