Date: Tue, 15 May 2001 10:37:11 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Terry Lambert <tlambert2@mindspring.com> Cc: dave <dleimbac@earthlink.net>, freebsd-questions@FreeBSD.ORG, arch@FreeBSD.ORG Subject: Re: Gettimeofday Again... Message-ID: <200105151737.f4FHbBL55271@earth.backplane.com> References: <200105150337.UAA19677@gull.mail.pas.earthlink.net> <200105150346.f4F3kLE45720@earth.backplane.com> <3B00EF40.A1232B75@mindspring.com>
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:I have an application where gettimeofday() was a significant
:fraction of the overhead; it was being used to provide for
:marketing eye-candy... basically, squid-compatible proxy
:logging that could be processed using common eye-candy tools
:normally used against squid logs for transaction in, time
:sent to back end, time data came from back end, and time data
:sent to client.
:
:The gettimeofday() calls were _the_ major useless overhead,
:until I eliminated them by creating a zero system call version
Terry, to be blunt... if you need performance you don't go making
superfluous system calls for every transaction. If you want marketing
eye candy, all you need to do is a statistical measurement... do fine
measurement of 10% of the transactions rather then fine measurement
of 100% of the transaction, and you are done.
Also, using gettimeofday() is a ridiculous way to measure fine grained
time billions of times in production code. I mean, sure, it works...
but getitimer() is about 5 times faster.
-Matt
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