On Tue, Dec 06, 2011 at 07:44:38PM +0800, Wu Fengguang wrote:
> > +#include <linux/seq_file.h>
> > +#include <linux/percpu.h>
> > +#include <linux/kernel.h>
> > +
> > +/* OPEN: implement module support */
>
> Yeah, I think the module support would benefit my case as well.
>
> To support module users, init_counters() will be exported with the
> __start___debugfs/__stop___debugfs hard coding removed. Then I'll be
> call it from the readahead initilization code:
No, the module loader should take care of this: look for the magic
section, register it. This is already done for other magic
sections and not too difficult, i just didn't write the code
so far.
Then the DEFINE_* macros would work seamlessly in modules too.
Do you really need it for the readahead code? I thought that
was builtin.
>
> DEFINE_PER_CPU(unsigned long[RA_PATTERN_MAX][RA_ACCOUNT_MAX], ra_counter);
> struct debugfs_counter ra_pcpu_counter[RA_PATTERN_MAX][RA_ACCOUNT_MAX];
>
> // init ra_pcpu_counter in a loop
> for each pattern
> init_counters(ra_pcpu_counter[pattern], ra_pcpu_counter[pattern+1]);
Ok so you need arrays.
The idea is to not call some init function, but just put it into section
and let the init code walk it.
Should probably have a macro that handles arrays nicely.
> > +static int show_debugfs_counter(struct seq_file *m, void *arg)
> > +{
> > + int n;
> > + n = dump_counters(m, __start___debugfs, __stop___debugfs, m->private);
>
> That hard coded __start___debugfs/__stop___debugfs is OK for POC, and
> will need to be improved to work with multiple users in kernel.
For Modules it obviously has to walk a list. It's a straight forward extension.
I don't think it should allow everyone to register their own lists,
that doesn't make sense because they could as well create the debug
files themselves.
-Andi
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