At 01:27 PM 9/13/2006, Robert Watson wrote:
The other common optimization advice that you may already have
received is to check which time counter FreeBSD has selected. Right
now, 6.x/7.x err on the side of accurate over fast. There's been
quite a bit of debate about this approach, and it's useful to
investigate the issue. You can view and set the current choice by
looking at the sysctl kern.timecounter.hardware, and you can see the
choices on your hardware by looking at kern.timecounter.choice.
Typically, TSC is the fastest, but may suffer from drift as the CPU changes
Hi,
How safe is TSC on SMP systems on RELENG_6 ? Do you still
have to boot with kern.timecounter.smp_tsc="1" in /boot/loader.conf ?
I was able to set it to TSC on my SMP box
# sysctl kern.timecounter
kern.timecounter.tick: 1
kern.timecounter.choice: TSC(-100) ACPI-fast(1000) i8254(0) dummy(-1000000)
kern.timecounter.hardware: TSC
kern.timecounter.nsetclock: 4
kern.timecounter.ngetmicrotime: 1710689523
kern.timecounter.ngetnanotime: 0
kern.timecounter.ngetbintime: 0
kern.timecounter.ngetmicrouptime: 417696361
kern.timecounter.ngetnanouptime: 6622371
kern.timecounter.ngetbinuptime: 17943777
kern.timecounter.nmicrotime: 2454574760
kern.timecounter.nnanotime: 1315721638
kern.timecounter.nbintime: 3770262461
kern.timecounter.nmicrouptime: 407340
kern.timecounter.nnanouptime: 1397760
kern.timecounter.nbinuptime: 3787035688
kern.timecounter.stepwarnings: 0
kern.timecounter.smp_tsc: 0
But the console fills up with
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379728 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379758 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379789 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379819 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379849 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379879 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379910 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379940 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335379970 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380002 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380032 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380065 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380096 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380126 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380156 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380186 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380216 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380247 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380277 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380307 usec for pid 66442 (clamd)
Sep 13 13:47:57 pumice1 kernel: calcru: runtime went backwards from
6336196518 usec to 6335380337 usec for pid 66442 (clamd)
So I set things back to
kern.timecounter.hardware: ACPI-fast
---Mike
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