From: Willy Tarreau <willy@w.ods.org>
To: "Richard B. Johnson" <root@chaos.analogic.com>
Cc: Robert Love <rml@tech9.net>,
Neil Conway <nconway.list@ukaea.org.uk>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] 2.4: variable HZ
Date: Sat, 19 Oct 2002 11:36:10 +0200 [thread overview]
Message-ID: <20021019093610.GA16046@alpha.home.local> (raw)
In-Reply-To: <Pine.LNX.3.95.1021018152117.150B-100000@chaos.analogic.com>
On Fri, Oct 18, 2002 at 03:38:43PM -0400, Richard B. Johnson wrote:
> If you are not using ELAN, CLOCK_TICK_RATE is 1193180.
well, in fact it's 1193181.666... (14318180/12).
> If your HZ is 100, you have 1193180/100 = 1193.18, not too exact.
you meant 1000, I suppose ?
> if you use 500, you get 1193180/500 = 2386.36 which has twice as much
> round-off. If you use 1193180/512 = 2330.43, even a higher fractional
> part.
those interested can try 511 Hz (/2334.994) or 1900 Hz (/627.990) which
has the double advantage of being multiple of 100 Hz and have a little
drift due to frac part (/628 gives 1899.97 Hz, and /627 gives 1903.001 Hz).
If you don't need a multiple of 100 Hz, I noticed that dividing by 5709
gives 209.0001 Hz.
I'm also wondering why we never use the RTC as an interrupt source. Are
there any incompatible PCs ?
Cheers,
Willy
next prev parent reply other threads:[~2002-10-19 9:30 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-18 11:51 [PATCH] 2.4: variable HZ Neil Conway
2002-10-18 18:44 ` Robert Love
2002-10-18 19:38 ` Richard B. Johnson
2002-10-19 7:04 ` jdow
2002-10-21 13:13 ` Richard B. Johnson
2002-10-19 9:36 ` Willy Tarreau [this message]
2002-10-21 8:15 ` Neil Conway
-- strict thread matches above, loose matches on Subject: below --
2002-10-15 6:03 Robert Love
2002-10-15 6:50 ` Robert Love
2002-10-18 18:27 ` Tim Schmielau
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