On Jun 19, 2012 8:30 PM, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:
>
> Zcache (in staging) has a large number of read-only counters that
> are primarily of interest to developers. These counters are currently
> visible from sysfs. However sysfs is not really appropriate and
> zcache will need to switch to debugfs before it can be promoted
> out of staging.
>
> For some of the counters, it is critical that they remain accurate so
> an atomic_t must be used. But AFAICT there is no way for debugfs
> to work with atomic_t.
Which ones must be atomic? Do they really need to be atomic if they are for diagnostics/developers?
>
> Is that correct? Or am I missing something?
>
> Assuming it is correct, I have a workaround but it is ugly:
>
> static unsigned long counterX;
> static atomic_t atomic_counterX;
>
> counterX = atomic_*_return(atomic_counterX)
>
> and use atomic_counter in normal code and counter for debugfs.
>
> This works but requires each counter to be stored twice AND
> makes the code look ugly.
But only for those counters that truly must be atomic.
>
> Is there a better way? I can probably bury the ugliness in
> macros but that doesn't solve the duplicate storage. (Though
> since there are only about a dozen, maybe it doesn't matter?)
A dozen that _MUST_ be atomic?
>
> Thanks,
> Dan
>
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