Hello, Josef. On Wed, Oct 26, 2016 at 11:20:16AM -0400, Josef Bacik wrote: > > > @@ -3701,7 +3703,20 @@ static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat) > > > if (unlikely(delta > nr_pagecache_reclaimable)) > > > delta = nr_pagecache_reclaimable; > > > > > > - return nr_pagecache_reclaimable - delta; > > > + nr_metadata_reclaimable = > > > + node_page_state(pgdat, NR_METADATA_BYTES) >> PAGE_SHIFT; > > > + /* > > > + * We don't do writeout through the shrinkers so subtract any > > > + * dirty/writeback metadata bytes from the reclaimable count. > > > + */ > > > > Hmm... up until this point, the dirty metadata was handled the same > > way as regular dirty data but it deviates here. Is this right? The > > calculations in writeback code also assumes that the dirty pages are > > reclaimable. If this is inherently different, it'd be nice to explain > > more explicitly why this is different from others. > > So there is logic above this that subtracts out the NR_FILE_DIRTY from the > file reclaimable if we can't do write's during reclaim. Since we can always > wait on writeback during reclaim it doesn't subtract out writeback. I took > this to mean that the general expectation of this function is to only count > thing things that the shrinker can specifically reclaim itself, so I > discounted anything under io since the slab shrinkers have no idea if its ok > to write or not and so in the case of btrfs simply skip anything that is > dirty or under writeback. Does that make sense? I'll fix up the other > issues you pointed out. Thanks, Yeap, that makes sense to me. Thanks for the explanation. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
