Hi all,
I've an environment 9.4 + bdr: PostgreSQL 9.4.4 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.7.2-5) 4.7.2, 64-bit kernel version: 3.2.0-4-amd64 #1 SMP Debian 3.2.65-1 x86_64 GNU/Linux This is consolidation databases, in this machine there are around 250+ wal sender processes. top output revealed high system cpu: %Cpu(s): 1.4 us, 49.7 sy, 0.0 ni, 48.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st profiling cpu with perf: perf top -e cpu-clock Events: 142K cpu-clock 82.37% [kernel] [k] __mutex_lock_common.isra.5 4.49% [kernel] [k] do_raw_spin_lock 2.23% [kernel] [k] mutex_lock 2.16% [kernel] [k] mutex_unlock 2.12% [kernel] [k] arch_local_irq_restore 1.73% postgres [.] ValidXLogRecord 0.87% [kernel] [k] __mutex_unlock_slowpath 0.78% [kernel] [k] arch_local_irq_enable 0.63% [kernel] [k] sys_recvfrom finally get which processes (wal senders) that are using mutexes: perf top -e task-clock -p 55382 Events: 697 task-clock 88.08% [kernel] [k] __mutex_lock_common.isra.5 3.27% [kernel] [k] do_raw_spin_lock 2.34% [kernel] [k] arch_local_irq_restore 2.10% postgres [.] ValidXLogRecord 1.87% [kernel] [k] mutex_unlock 1.87% [kernel] [k] mutex_lock 0.47% [kernel] [k] sys_recvfrom I think bdr is only reading wal file (current state is we behind current wal lsn), so why reading wal file needs mutex? I wonder, is there kernel version has better handling mutexes? -- regards ujang jaenudin | DBA Consultant (Freelancer) http://ora62.wordpress.com http://id.linkedin.com/pub/ujang-jaenudin/12/64/bab
