On Tue, May 13, 2014 at 11:34 PM, Greg Stark <st...@mit.edu> wrote: > I always assumed the kernel used rdtsc to implement some of the high > performance timers. It can save the current time in a mapped page when > it schedules a process and then in the vdso syscall (ie in user-space) > it can use rdtsc to calculate the offset needed to adjust that > timestamp to the current time. This seems consistent with your > calculations that showed the 40ns overhead with +/- 10ns precision.
Crazy idea: Instead of trying to time precisely the amount of time we spend in each node, configure a very-high frequency timer interrupt (or background thread?) that does: SomeGlobalVariablePointingToTheCurrentNode->profiling_counter++; -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
