Re: [PATCH/RFC] msleep() with hrtimers

From: Nick Piggin
Date: Wed Jul 18 2007 - 12:29:36 EST


Nish Aravamudan wrote:

Well, before these changes, the only guarantee msleep() could make,
just like the only guarantee schedule_timeout() could make, was that
it would not return early. The 1-jiffy sleep was always tough to deal
with, because of rounding and such. And it's simply exacerbated with
HZ=100. It's not technically 20 times longer in all cases, it's 2
jiffies longer, which depends on HZ, so varies from 2 msecs longer to
20 msecs longer.

I don't think you should rely on anything else actually, because Linux
is not an RT OS. If your driver needs a specific sequence in a given
amount of time, you have to do something like disable interrupts and
use delays.

--
SUSE Labs, Novell Inc.
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