On Mon, May 28, 2018 at 10:15:46AM +0200, Vlastimil Babka wrote: > On 05/24/2018 05:32 PM, Johannes Weiner wrote: > > On Thu, May 24, 2018 at 01:00:06PM +0200, Vlastimil Babka wrote: > >> - the vmstat/meminfo counter name is rather general and might suggest it also > >> includes reclaimable page caches, which it doesn't > >> > >> Suggestions welcome for all three points. For the last one, we might also keep > >> the counter separate from nr_slab_reclaimable, not superset. I did a superset > >> as IIRC somebody suggested that in the older threads or at LSF. > > > > Yeah, the "reclaimable" name is too generic. How about KReclaimable? > > > > The counter being a superset sounds good to me. We use this info for > > both load balancing and manual debugging. For load balancing code it's > > nice not having to worry about finding all the counters that hold > > reclaimable memory depending on kernel version; it's always simply > > user cache + user anon + kernel reclaimable. And for debugging, we can > > always add more specific subset counters later on if we need them. > > Hm, Christoph in his reply to patch 4/5 expressed a different opinion. > It's true that updating two counters has extra overhead, especially if > there are two separate critical sections: > > mod_lruvec_page_state(page, NR_SLAB_RECLAIMABLE, nr_pages); > mod_node_page_state(page_pgdat(page), NR_RECLAIMABLE, nr_pages); > > The first disables irq for CONFIG_MEMCG or defers to > mod_node_page_state() otherwise. > mod_node_page_state() is different depending on CONFIG_SMP and > CONFIG_HAVE_CMPXCHG_LOCAL. > > I don't see an easy way to make this optimal? Different counter would be > indeed simpler. /proc/vmstat would then print separate counters, but we > could have both separate and summary counter in /proc/meminfo. Would > that be enough? Yeah, that works just as well. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
