[lkml]   [2001]   [Jan]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] 2.4.0-prerelease: preemptive kernel.
ludovic fernandez wrote:
> The following patch makes the kernel preemptable.
> It is against 2.4.0-prerelease on for i386 only.
> It should work for UP and SMP even though I
> didn't validate it on SMP.
> Comments are welcome.

I was expecting to see this sometime in 2.5, not quite so soon...

The key idea here is to disable preemption on spin lock and reenable on
spin unlock. That's a practical idea, highly compatible with the
current way of doing things. Its a fairly heavy hit on spinlock
performance, but maybe the overall performance hit is small. Benchmarks
are needed.

A more ambitious way to proceed is to change spinlocks so they can sleep
(not in interrupts of course). There would not be any extra overhead
for this on spin_lock (because the sleep test is handled off the fast
path) but spin_unlock gets a little slower - it has to test and jump on
a flag if there are sleepers.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

 \ /
  Last update: 2005-03-22 12:52    [W:0.173 / U:1.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site