cvs commit: src/sys/i386/i386 local_apic.c

[John Baldwin]

On Monday 26 January 2004 03:08 pm, Jeff Roberson wrote:
> On Mon, 26 Jan 2004, John Baldwin wrote:
> > On Sunday 25 January 2004 12:03 am, Jeff Roberson wrote:
> > > jeff        2004/01/24 21:03:14 PST
> > >
> > >   FreeBSD src repository
> > >
> > >   Modified files:
> > >     sys/i386/i386        local_apic.c
> > >   Log:
> > >    - Don't define DETECT_DEADLOCK.  I don't know that this code has
> > > detected a deadlock in several years.  Furthermore, the IPI code is
> > > currently protected by a seperate spinlock.  This only served to make
> > > IPIs twice as expensive as they had to be which severely slowed down
> > > the IPI heavy ULE scheduler.
> >
> > What spinlock?
>
> Er, based on earlier conversations with you I was under the assumption
> that there was a lock around all of the ipi sender code.  I must have this
> confused with something else.

Ah, ok.

> > > grep mtx local_apic.c  | wc -l
> >
> >        0
> >
> > Some users of the ipi API use a spinlock themselves, but not all, and
> > there certainly isn't a global ipi spin lock.  According to witness, only
> > sparc64 has an ipi spin lock.  It might still be a good idea to turn this
> > off or perhaps at least half of it.  We will lose ipi's on non-XAPIC
> > systems if you don't wait for the delivery status to clear before sending
> > an IPI.  Have you tested this on Pentium II's or earlier?
>
> My original patch did still poll before transmit.  I'll correct this.

Thanks.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org