Hello All,
Recently, I have been involved in some work that requires me to monitor low level performance counters for pgsql. Specifically, when I execute a particular query I want to be able to tell how many system calls get executed on behalf of that query and time of each sys call. The idea is to provide a break down of the total query running time in terms of CPU time (user+system) and IO (wait time + service time) and any other contributing factors.
I have been using various performance monitoring tool in linux including vmstat, mpstat, iostat and strace(to monitor system calls). Surprisingly, no matter what type of query I execute, when I use strace to monitor the system calls generated they turn out to be the same for ALL sorts of queries. Now this could happen because (a) the tool (strace) is not robust (b) something the pgsql code is doing that eludes strace. At this point I have been unable to narrow it down. Any help in this regard will be greatly appreciated. Also if somebody knows a better way of achieving the same goal please let me know.
Thanks for reading.
-Umar
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