On 29.09.2017 00:02, Andrew Morton wrote: > On Thu, 28 Sep 2017 10:48:55 +0300 Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> wrote: > >>>> This patch aims to make super_cache_count() (and other functions, >>>> which count LRU nr_items) more effective. >>>> It allows list_lru_node::memcg_lrus to be RCU-accessed, and makes >>>> __list_lru_count_one() count nr_items lockless to minimize >>>> overhead introduced by locking operation, and to make parallel >>>> reclaims more scalable. >>> >>> And... what were the effects of the patch? Did you not run the same >>> performance tests after applying it? >> >> I've just detected the such high usage of shrink slab on production node. It's rather >> difficult to make it use another kernel, than it uses, only kpatches are possible. >> So, I haven't estimated how it acts on node's performance. >> On test node I see, that the patch obviously removes raw_spin_lock from perf profile. >> So, it's a little bit untested in this way. > > Well that's a problem. The patch increases list_lru.o text size by a > lot (4800->5696) which will have a cost. And we don't have proof that > any benefit is worth that cost. It shouldn't be too hard to cook up a > synthetic test to trigger memcg slab reclaim and then run a > before-n-after benchmark? Ok, then, please, ignore this for a while, I'll try to do it a little bit later. Kirill -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
