[lkml]   [2002]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [2.4.17/18pre] VM and swap - it's really unusable
Stephan von Krawczynski wrote:
> On Mon, 14 Jan 2002 02:04:56 -0800
> Andrew Morton <> wrote:
> > Stephan von Krawczynski wrote:
> > >
> > > ...
> > > Unfortunately me have neither of those. This would mean I cannot benefit
> from> > _these_ patches, but instead would need _others_
> [...]
> >
> > In 3c59x.c, probably the biggest problem will be the call to issue_and_wait()
> > in boomerang_start_xmit(). On a LAN which is experiencing heavy collision
> rates> this can take as long as 2,000 PCI cycles (it's quite rare, and possibly
> an> erratum). It is called under at least two spinlocks.
> >
> > In via-rhine, wait_for_reset() can busywait for up to ten milliseconds.
> > via_rhine_tx_timeout() calls it from under a spinlock.
> >
> > In eepro100.c, wait_for_cmd_done() can busywait for one millisecond
> > and is called multiple times under spinlock.
> Did I get that right, as long as spinlocked no sense in conditional_schedule()
> ?
> > Preemption will help _some_ of this, but by no means all, or enough.
> Maybe we should really try to shorten the lock-times _first_. You mentioned a
> way to find the bad guys?

Apply the preempt patch and then the preempt-stats patch. Follow
instructions that come with the stats patch. It will report on the
longest preempt disable times since the last report. You need to
provide a load that will exercise the bad code, but it will tell you
which, where, and how bad. Note: it measures preempt off time, NOT how
long it took to get to some task, i.e. it does not depend on requesting
preemption at the worst possible time.
Real time sched:
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:15    [W:0.142 / U:2.840 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site