Testing lockless cache in ASE16SP02

[Former Member]

In our 64 engine systems we generate 250 to 300 billions logical IOs in a given day. At peak loads we run out of CPU resources mostly from SPINLOCK Contention. We currently have 22 named caches. We have a good sprinkle of "Relaxed LRU" caches among the 22 where in we bind small but frequently used tables. We know for a fact these are good candidates for Lockless cache. The size of the cache is larger than the elements it is bound to.

Here is the test results we have from one such lockless cache we had configured. Jeff Tallman was in our premises last Friday and we were seeking his advise on what should be criteria for turning on Lockless cache. His matrix was physical reads to logical reads ratio. However, we also dwelled into size of the cache vs sum of pages read (sum of buffers to lru and buffers to mru). I think we will have to test further to see on best we can minimize spins on our caches.

Lockless Cache feature shows great promise in our desire to scale up. We are introducing 80 engine/3TB boxes boxes into our estate and I am looking forward to the task of scaling these new beasts.

BTW: We had a great session from Jeff on ASE16SP02.

	GRABS	SPINS	WAITS
Lockless Relaxed	35,085	61,329	677
Mixed Relaxed LRU	71,993,182	19,013,646	1,543,098
Mixed Strict LRU	71,992,392	55,426,651	2,406,482