[RFC][PATCH 0/4] new human-time soft-timer subsystem

[Nishanth Aravamudan <nacc@us.ibm.com>]

On 14.07.2005 [12:18:41 -0700], john stultz wrote:

<snip>

> Nish has some code, which I hope he'll be sending out shortly that
> does just this, converting the soft-timer subsystem to use absolute
> time instead of ticks for expiration. I feel it both simplifies the
> code and makes it easier to changing the timer interrupt frequency
> while the system is running.

Here's the set of patches John promised :)

1/4: add jiffies conversion helper functions

2/4: core human-time modifications to soft-timer subsystem

3/4: add new human-time schedule_timeout() functions

4/4: rework sys_nanosleep() to use schedule_timeout_nsecs()

The individual patches have more details, but the gist is this:

We no longer use jiffies (the variable) as the basis for determining
what "time" a timer should expire or when it should be added. Instead,
we use a new function, do_monotonic_clock(), which is simply a wrapper
for getnstimeofday(). That is to say, we use uptime in nanoseconds. But,
to avoid modifying the existing soft-timer algorithm, we convert the
64-bit nanosecond value to "timerinterval" units. These units are simply
2^TIMEINTERVAL_BITS nanoseconds in length (thus determined at compile
time).

To sum up, soft-timers now use time (as defined by the
timeofday-subsystem) not ticks. Hopefully, the individual
e-mails/patches make this change clear.

Thanks,
Nish