Skip site navigation (1)Skip section navigation (2)
Date:      Tue, 29 Nov 2011 19:34:25 +0100
From:      Ireneusz Pluta <ipluta@wp.pl>
To:        freebsd-questions@freebsd.org
Subject:   kern.timecounter.hardware change on the fly
Message-ID:  <4ED525B1.3010100@wp.pl>

Next in thread | Raw E-Mail | Index | Archive | Help
Hi all,

is it safe to change kern.timecounter.hardware on a busy production system on the fly? Or I better 
schedule a downtime to do that?

It seems I got a bad current selection, somehow, probably as an effect of leaving /etc/sysctl.conf 
contents of early experimental setup stage of this machine.

$ sysctl -a | grep timecounter
kern.timecounter.tick: 1
kern.timecounter.choice: TSC(-100) HPET(900) ACPI-fast(1000) i8254(0) dummy(-1000000)
kern.timecounter.hardware: i8254
kern.timecounter.stepwarnings: 0
kern.timecounter.tc.i8254.mask: 65535
kern.timecounter.tc.i8254.counter: 23813
kern.timecounter.tc.i8254.frequency: 1193182
kern.timecounter.tc.i8254.quality: 0
kern.timecounter.tc.ACPI-fast.mask: 16777215
kern.timecounter.tc.ACPI-fast.counter: 4619803
kern.timecounter.tc.ACPI-fast.frequency: 3579545
kern.timecounter.tc.ACPI-fast.quality: 1000
kern.timecounter.tc.HPET.mask: 4294967295
kern.timecounter.tc.HPET.counter: 1703441786
kern.timecounter.tc.HPET.frequency: 14318180
kern.timecounter.tc.HPET.quality: 900
kern.timecounter.tc.TSC.mask: 4294967295
kern.timecounter.tc.TSC.counter: 2720513805
kern.timecounter.tc.TSC.frequency: 2266656152
kern.timecounter.tc.TSC.quality: -100
kern.timecounter.smp_tsc: 0
kern.timecounter.invariant_tsc: 1

This setting seems to affect what is generally described here: 
http://archives.postgresql.org/pgsql-admin/2011-01/msg00059.php and this is the primary reason I 
want to change.

Should I switch to HPET or ACPI-fast?



Want to link to this message? Use this URL: <http://docs.FreeBSD.org/cgi/mid.cgi?4ED525B1.3010100>