Re: [PATCH] Consolidate multiple implementations of jiffies-msecsconversions.

From: Jeff Garzik
Date: Fri Mar 26 2004 - 14:05:16 EST

Sridhar Samudrala wrote:
On Fri, 26 Mar 2004, Edgar Toernig wrote:

Sridhar Samudrala wrote:

The following patch to 2.6.5-rc2 consolidates 6 different implementations
of msecs to jiffies and 3 different implementation of jiffies to msecs.
All of them now use the generic msecs_to_jiffies() and jiffies_to_msecs()
that are added to include/linux/time.h
-#define MSECS(ms) (((ms)*HZ/1000)+1)
-return (((ms)*HZ+999)/1000);
+return (msecs / 1000) * HZ + (msecs % 1000) * HZ / 1000;

Did you check that all users of the new version will work correctly
with your rounding? Explicit round-up of delays is often required,
especially when talking to hardware...

I don't see any issues with the 2.6 default HZ value of 1000 as they become
no-ops and there is no need for any rounding.
I guess you are referring to cases when HZ < 1000(ex: 100) and msecs is
less than 10. In those cases, the new version returns 0, whereas some of the
older versions return 1.

We'll definitely want to return 1 rather than zero, for the uses in my drivers, at least...


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