remove __read_mostly?
From: Andrew Morton
Date: Sun Jun 25 2006 - 14:56:27 EST
I'm thinking we should remove __read_mostly.
Because if we use this everywhere where it's supposed to be used, we end up
with .bss and .data 100% populated with write-often variables, packed
closely together. The cachelines will really flying around.
IOW: __read_mostly optimises read-mostly variables and pessimises
write-often variables.
We want something which optimises both read-mostly and write-often storage.
We do that by marking the write-often variables with
__cacheline_aligned_in_smp.
OK?
[Problem is, I don't think any of the make-foo-__read_mostly patches
actually identified _which_ write-often variables were affecting `foo', so
we'll be back to square one.]
[Actually, we should do
#define __write_often __cacheline_aligned_in_smp
and use __write_often
a) for documentation and
b) so the optimisation can be centrally turned off, for space
optimisation or for performance validation.]
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