On Wed, Sep 29, 2010 at 09:53:22PM -0700, Andrew Morton wrote:
> On Wed, 29 Sep 2010 22:18:48 +1000 Dave Chinner <david@xxxxxxxxxxxxx> wrote:
>
> > From: Eric Dumazet <dada1@xxxxxxxxxxxxx>
> >
> > The number of inodes allocated does not need to be tied to the
> > addition or removal of an inode to/from a list. If we are not tied
> > to a list lock, we could update the counters when inodes are
> > initialised or destroyed, but to do that we need to convert the
> > counters to be per-cpu (i.e. independent of a lock). This means that
> > we have the freedom to change the list/locking implementation
> > without needing to care about the counters.
> >
> >
> > ...
> >
> > +int get_nr_inodes(void)
> > +{
> > + int i;
> > + int sum = 0;
> > + for_each_possible_cpu(i)
> > + sum += per_cpu(nr_inodes, i);
> > + return sum < 0 ? 0 : sum;
> > +}
>
> This reimplements percpu_counter_sum_positive(), rather poorly
I thought so - it was on my list of things to check when redoing
this patch. I'll fix that up appropritately.
>
> If one never intends to use the approximate percpu_counter_read() then
> one could initialise the counter with a really large batch value, for a
> very small performance gain.
>
> > +int get_nr_inodes_unused(void)
> > +{
> > + return inodes_stat.nr_unused;
> > +}
> >
> > ...
> >
> > @@ -407,6 +407,8 @@ extern struct files_stat_struct files_stat;
> > extern int get_max_files(void);
> > extern int sysctl_nr_open;
> > extern struct inodes_stat_t inodes_stat;
> > +extern int get_nr_inodes(void);
> > +extern int get_nr_inodes_unused(void);
>
> These are pretty cruddy names. Unfotunately we don't really have a vfs
> or "inode" subsystem name to prefix them with.
Will fix.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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