[PATCH 6/7] libxfs: keep unflushable buffers off the cache MRUs

[Dave Chinner]

On Mon, Feb 08, 2016 at 02:06:36AM -0800, Christoph Hellwig wrote:
> > --- a/include/cache.h
> > +++ b/include/cache.h
> > @@ -51,6 +51,7 @@ enum {
> >  #define CACHE_BASE_PRIORITY	0
> >  #define CACHE_PREFETCH_PRIORITY	8
> >  #define CACHE_MAX_PRIORITY	15
> > +#define CACHE_DIRTY_PRIORITY	(CACHE_MAX_PRIORITY + 1)
> 
> Sizing arrays based on, and iterating up to CACHE_DIRTY_PRIORITY seems
> rather odd.  Maybe add a new
> 
> #define CACHE_NR_PRIORITIES		CACHE_DIRTY_PRIORITY
> 
> and a comment explaining the magic to make it more obvious?

Ok.

> > +cache_move_to_dirty_mru(
> > +	struct cache		*cache,
> > +	struct cache_node	*node)
> > +{
> > +	struct cache_mru	*mru;
> > +
> > +	mru = &cache->c_mrus[CACHE_DIRTY_PRIORITY];
> > +
> > +	pthread_mutex_lock(&mru->cm_mutex);
> > +	node->cn_priority = CACHE_DIRTY_PRIORITY;
> > +	list_move(&node->cn_mru, &mru->cm_list);
> > +	mru->cm_count++;
> > +	pthread_mutex_unlock(&mru->cm_mutex);
> > +}
> 
> Maybe it would better to just do a list_add here and leave the
> list_del to the caller to avoid needing to nest two different
> cm_mutex instances.

I'll have a look at it.

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com