On Fri, Oct 30, 2015 at 5:12 PM, Andres Freund <andres@anarazel.de> wrote:
On 2015-10-30 16:28:22 +0300, Alexander Korotkov wrote: > pinunpin-cas-original-fix.patch is just original patch by Andres Freund > with fixed bug which causes hang. > Performance comparison on 72-cores Intel server in attached. On this > machine we see no regression in version of patch in previous letter.
So pinunpin-cas-original-fix is my version with a bug fixed, and pinunpin-cas is what exactly? Your earlier version with the xadd + cmpxchg?
pinunpin-cas is still just cmpxchg with no xadd. It contain just minor changes:
Refactored version of atomic state patch is attached. The changes are following: 1) Macros are used for access refcount and usagecount. 2) likely/unlikely were removed. I think introducing of likely/unlikely should be a separate patch since it touches portability. Also, I didn't see any performance effect of this. 3) LockBufHdr returns the state after taking lock. Without using atomic increments it still can save some loops on skip atomic value reading.
I compare them just to show there is no regression because of these changes.
The results look pretty good. Could you give a few more details about the hardware and workload (i.e. cpu model number + scale)?
It is 4 socket Intel(R) Xeon(R) CPU E7-8890 v3 @ 2.50GHz, 2 Tb of memory, all data in shared_buffers, 1000 scale factor, -M prepared, pgbench runs on the same maching through unix socket.
So the plan would be to finish cleaning this up into a committable shape?
