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Date: Fri, 28 Oct 2005 13:00:07 -0700
From: John-Mark Gurney <gurney_j@resnet.uoregon.edu>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
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Cc: current@freebsd.org
Subject: Re: Timers and timing, was: MySQL Performance 6.0rc1
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Poul-Henning Kamp wrote this message on Fri, Oct 28, 2005 at 11:56 +0200:
> In message <4361F057.4030904@pp.nic.fi>, Pertti Kosunen writes:
> 
> >Does polling affect to this test?
> 
> Not apart from the CPU overhead.
> 
> 	sysctl kern.timecounter.hardware
> 
> is much more important.
> 
> and all the reports here which fail to include it are mostly
> useless.

hydrogen,ttypa,/tmp,504$grep CPU /var/run/dmesg.boot
CPU: AMD Duron(tm) Processor (1211.94-MHz 686-class CPU)
hydrogen,ttypa,/tmp,501#sysctl kern.timecounter.hardware=TSC
kern.timecounter.hardware: TSC -> TSC
hydrogen,ttypa,/tmp,502#./timer
       null function: 0.00165
            getpid(): 0.37850
              time(): 0.65022
      gettimeofday(): 0.60886
hydrogen,ttypa,/tmp,503#sysctl kern.timecounter.hardware=ACPI-fast
kern.timecounter.hardware: TSC -> ACPI-fast
hydrogen,ttypa,/tmp,504#./timer
       null function: 0.00165
            getpid(): 0.38530
              time(): 1.33242
      gettimeofday(): 1.33421

I was quite impressed by the speed up using the TSC over ACPI-fast...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."