Re: [PATCH v2] consolidate WARN_...ONCE() static variables

[Andrew Morton]

On Tue, 28 Feb 2012 07:41:54 +0000 "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> >>> On 28.02.12 at 01:03, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> > On Mon, 27 Feb 2012 15:10:34 +0000
> > "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> > 
> >> Due to the alignment of following variables, these typically consume
> >> more than just the single byte that 'bool' requires, and as there are
> >> a few hundred instances, the cache pollution (not so much the waste of
> >> memory) sums up. Put these variables into their own section, outside
> >> of any half way frequently used memory range.
> >> 
> >> v2: Do the same also to the __warned variable of rcu_lockdep_assert().
> >> (Don't, however, include the ones used by printk_once() and alike, as
> >> they can potentially be hot.)
> > 
> > I have a bad feeling that I still don't understand this patch.  Ho hum.
> > 
> > What are the rules for the new .data.unlikely section?  When should
> > people put variables into this section?  Perhaps we can document this
> > somewhere?
> 
> If I knew the "where" part of this, I could put together a few sentences.
> I just grep-ed through Documentation/, without finding e.g. any rules
> or guidelines for using {,un}likely()...
>

At the definition site in vmlinux.lds?
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