Messages in this thread | | | Date | Thu, 2 Apr 2009 04:13:25 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH UPDATED] percpu: use dynamic percpu allocator as the default percpu allocator |
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* Matthew Wilcox <matthew@wil.cx> wrote:
> On Wed, Apr 01, 2009 at 12:39:46PM -0700, Linus Torvalds wrote: > > > The thing is, things like "read_mostly" or "access_rarely" may > > talk about how we access those individual variables, but you're > > missing a _huge_ chunk of the puzzle if you ignore the > > _correlations_ of those accesses with accesses to other > > variables. > > > > The thign is, if you have variables 'a' and 'b', and they are > > always accessed together, then it's probably worth it to put > > them in the same cacheline. > > If you've got two global variables that are generally accessed > together, they should probably be `annotated' as such by putting > them in a struct.
It is certainly done so in a number of cases (say the RCU core and the scheduler), but i dont think it should be forced or preferred in any way.
IMHO it's equally good and clean code to have the global variables separately at the top of a .c file. Sometimes it's cleaner.
Ingo
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