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SubjectRe: jiffies wrap question...
On Fri, Nov 10, 2000 at 02:21:28AM -0500, Jeff Garzik wrote:
> The following is a piece of code from the latter half of
> schedule_timeout, in kernel/sched.c. Is it possible that
> schedule_timeout could return an incorrect value, if the jiffy value
> wraps between the first and last lines shown below.

let's say the first line happens n ticks before the wrap and the second,
m ticks afterwards.

> expire = timeout + jiffies;

expire = timeout + 2^32/2^64 - n = timeout - n

> timeout = expire - jiffies;

timeout = expire - m = timeout - n - m = timeout - (n+m)

(n+m) is the time that actually passed while we were asleep, and timeout
has the correct value (timeout - ticks that happened)>
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