Re: low-latency scheduling patch for 2.4.0

Andrew Morton
2001-01-14T11:29:23Z

Andrew Morton wrote:
>
> A patch against kernel 2.4.0 final which provides low-latency
> scheduling is at
>
> http://www.uow.edu.au/~andrewm/linux/schedlat.html#downloads
>

This has been updated for 2.4.1-pre3

- Fixed latency problems with some /proc files and forking
when many files are open.

- Fixed the tcp-minisocks thing.

- The patch now works properly on SMP.

If a wakeup is directed to a SCHED_FIFO or SCHED_RR
task then we request a reschedule on *all* non-idle
CPUs.

This causes any CPU which is holding a long-lived
spinlock to bale out, allowing the target CPU to
acquire the spinlock and then reschedule normally.

Bit of a hack, but it works very well and there
is no impact on the system unless there are
non-SCHED_OTHER tasks running.

Five lines of code :)