I see significant performance difference between systems using Linux kernel 3.10 and 3.12. We did tests on CentOS7 (kernel 3.10) and SuSE Enterprise Linux Server 12 (kernel 3.12).
Both systems run on VMWare ESXi 5.5.0. Xeon CPU E52650 2GHz x 2 (16 cores in total) Mem 96GB, 10,000 RPM SAS drive Guest OS setting: CPU 4 Mem 6GB file system ext4 PostgreSQL 9.3.5 compiled from source code (all parameters are default) The benchmark tables are created by "pgbench -i -s 500". "pgbench -S -c NUM -T 500" runs 3 times for each NUM concurrent users and we calculate the average TPS for the each run. We ran pgbench in 4 patters: 1) SLES12 (kernel 3.12) 2) CentOS7 (kernel 3.10 with default deadline scheduler) 3) CentOS7 (kernel 3.10 with cfq scheduler) 4) CentOS7 (kernel replaced with 3.12 with cfq scheduler) The result is roughly: #1 > #4 >> #2 >> #3 So it seems the performance difference is dominated by the kernel version difference (3.10 vs. 3.12). Does anybody know the cause? Note that kernel parameter "sched_autogroup" (which is available only with 3.10 kernel) did not give much difference. Best regards, -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese:http://www.sraoss.co.jp
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