Date: Wed, 5 Jul 2000 09:43:57 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Greg Lehey <grog@lemis.com> Cc: Chuck Paterson <cp@bsdi.com>, David Greenman <dg@root.com>, freebsd-smp@FreeBSD.ORG Subject: Re: SMP progress (was: Stepping on Toes) Message-ID: <200007051643.JAA88121@apollo.backplane.com> References: <200006261650.KAA17801@berserker.bsdi.com> <200006271742.KAA35851@apollo.backplane.com> <20000703112203.B61851@wantadilla.lemis.com>
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:...
:> At this moment, without interrupt threads, interrupts can share Giant
:> with the curproc they interrupted. This is how our existing MP stuff
:> worked already.
:>
:> When Greg moves interrupts to their own threads, and obtains Giant to
:> run those interrupts, no more sharing will occur and just the fact
:> that the interrupt is holding Giant guarentees that nobody else will
:> be messing with SPLs, thus the SPLs can be removed entirely.
:
:Agreed. I'm in the process of implementing the heavy-weight interrupt
:processes now. I've just taken a look at your web page and note that
:the URL no longer exists; in conjunction with the discussion above,
:I'm no longer sure how far you are. Are you importing the BSD/OS code
:now?
:
:We should probably take the rest of this offline, but I wanted to
:discuss how we do things. My idea is:
:
:1. You import the BSD/OS mutexes.
:2. I import/implement the heavy-weight interrupt code, which I will
: endeavour to get working relatively reliably. This should be a
: fallback while I break^H^H^H^H^Himplement light-wait interrupt
: threads.
:3. You and I test our stuff together until it can stay up for an hour
: or so (exact time to be determined by Jason, who'll be carrying
: the can).
:4. We commit the marginally stable stuff.
:5. I carry on working on the light-weight threads.
:
:Any comments?
:
:Greg
Jake Burkholder is porting the BSD/OS mutexes. I don't expect there
to be much of a difference in regards to your heavy-weight interrupt
work. I'm going to take a look at Jake's patchset tonight. I think
the only operational item we need to research is the sti/cli stuff in
the BSDI mutexes... we should be able to remove them at some point
(my interrupt code is already using the ipending mechanism to deal
with the scheduler mutex being active on the current cpu).
If Jake's removed that, then we'll want to put it back in at some point
since it saves a significant amount of overhead ('sti' and 'cli' are
expensive instructions).
-Matt
Matthew Dillon
<dillon@backplane.com>
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