Messages in this thread | | | Subject | Re: boot time, process start time, and NOW time | From | john stultz <> | Date | Tue, 17 Aug 2004 12:00:31 -0700 |
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On Mon, 2004-08-16 at 16:24, Albert Cahalan wrote: > On Mon, 2004-08-16 at 15:41, Andrew Morton wrote: > > > Where did this all end up? Complaints about > > wandering start times are persistent, and it'd > > be nice to get some fix in place... > > If you're interested in reducing (not solving) > the problem for the 2.6.x series, you might change > HZ to something that works better with the PIT. > > Here is a table showing % error for various HZ choices: > > wrongness_% HZ_diff PIT_# HZ actual_HZ > -0.00150855 -0.001509 11932 100 99.998491 > -0.00150855 -0.009474 1900 628 627.990526 > -0.00083809 -0.003051 3278 364 363.996949 > -0.00083809 -0.008389 1192 1001 1000.991611 > +0.00000000 +0.000000 14551 82 82.000000 > +0.00008381 +0.000304 3287 363 363.000304 > +0.00008381 +0.000435 2299 519 519.000435 > +0.00008381 +0.000525 1903 627 627.000525 > +0.01525566 +0.152557 1193 1000 1000.152557 > +0.01860917 +0.190558 1165 1024 1024.190558 > > As you can see, 1000 HZ and 1024 HZ are really bad. > They're worse than typical quartz crystal variation. > > The old 100 HZ tick was just barely tolerable. > While 82 is perfect, it's a bit low. :-( > > Some of the other choices are nice. How about 363, > 519, or 627?
What about 1001? That looks reasonably accurate.
thanks -john
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