On Wed, Mar 16, 2016 at 10:59 PM, Robert Haas <robertmh...@gmail.com> wrote:
> On Wed, Mar 16, 2016 at 4:40 AM, Mithun Cy <mithun...@enterprisedb.com> > wrote: > >> >> On Thu, Mar 3, 2016 at 6:20 AM, Mithun Cy <mithun...@enterprisedb.com> >> wrote: >> > I will continue to benchmark above tests with much wider range of >> clients. >> >> Latest Benchmarking shows following results for unlogged tables. >> >> clients BASE ONLY CLOG CHANGES % Increase CLOG CHANGES + SAVE SNAPSHOT % >> Increase >> 1 1198.326337 1328.069656 10.8270439357 1234.078342 2.9834948875 >> 32 37455.181727 38295.250519 2.2428640131 41023.126293 9.5259037641 >> 64 48838.016451 50675.845885 3.7631123611 51662.814319 5.7840143259 >> 88 36878.187766 53173.577363 44.1870671639 56025.454917 51.9203038731 >> 128 35901.537773 52026.024098 44.9130798434 53864.486733 50.0339263281 >> 256 28130.354402 46793.134156 66.3439197647 46817.04602 66.4289235427 >> > > Whoa. At 64 clients, we're hardly getting any benefit, but then by 88 > clients, we're getting a huge benefit. I wonder why there's that sharp > change there. > > If you see, for the Base readings, there is a performance increase up till 64 clients and then there is a fall at 88 clients, which to me indicates that it hits very high-contention around CLogControlLock at 88 clients which CLog patch is able to control to a great degree (if required, I think the same can be verified by LWLock stats data). One reason for hitting contention at 88 clients is that this machine seems to have 64-cores (it has 8 sockets and 8 Core(s) per socket) as per below information of lscpu command. Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 128 On-line CPU(s) list: 0-127 Thread(s) per core: 2 Core(s) per socket: 8 Socket(s): 8 NUMA node(s): 8 Vendor ID: GenuineIntel CPU family: 6 Model: 47 Model name: Intel(R) Xeon(R) CPU E7- 8830 @ 2.13GHz Stepping: 2 CPU MHz: 1064.000 BogoMIPS: 4266.62 Virtualization: VT-x L1d cache: 32K L1i cache: 32K L2 cache: 256K L3 cache: 24576K NUMA node0 CPU(s): 0,65-71,96-103 NUMA node1 CPU(s): 72-79,104-111 NUMA node2 CPU(s): 80-87,112-119 NUMA node3 CPU(s): 88-95,120-127 NUMA node4 CPU(s): 1-8,33-40 NUMA node5 CPU(s): 9-16,41-48 NUMA node6 CPU(s): 17-24,49-56 NUMA node7 CPU(s): 25-32,57-64 With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
