* Tom Lane: > Florian Weimer <f...@deneb.enyo.de> writes: >> * Tom Lane: >>> On Linux (RHEL6, 2.4GHz x86_64), I find that gettimeofday(), >>> clock_gettime(CLOCK_MONOTONIC), and clock_gettime(CLOCK_REALTIME) >>> all take about 40ns. Of course gettimeofday() only has 1us resolution, >>> but the other two have perhaps 10ns resolution (I get no duplicate >>> readings in a tight loop). > >> Isn't this very specific to kernel and glibc versions, depending on >> things like CONFIG_HZ settings and what level of vDSO support has been >> backported? > > No doubt, but I have yet to find a platform where clock_gettime() exists > but performs worse than gettimeofday(). Do you know of one?
ppc64le with all the vDSO fixes for clock_gettime? glibc has some test cases which fail because clock_gettime gives inconsistent results. This has been fixed in current kernels, but I don't know if everyone uses them. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
