Date: Wed, 10 Jul 2002 01:35:12 -0700 From: Peter Wemm <peter@wemm.org> To: John Baldwin <jhb@FreeBSD.org> Cc: current@freebsd.org Subject: Re: Remember my ill-fated i386 smp pmap optimizations? Message-ID: <20020710083512.AAF853808@overcee.wemm.org> In-Reply-To: <20020708205248.6D4EC3808@overcee.wemm.org>
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Peter Wemm wrote:
> John Baldwin wrote:
> >
> > On 08-Jul-2002 Peter Wemm wrote:
> > > A few months ago, I had a bit of a disaster with some pmap optimizations.
> > > After committing, all hell broke loose. It was backed out completely.
> > >
> > > I finally found the problem (diff cleaned up to highlight the problem):
> > >
> > > pmap_mapdev()
> > > ...
> > > for (tmpva = va; size > 0; ) {
> > > pte = vtopte(tmpva);
> > > *pte = pa | PG_RW | PG_V | pgeflag;
> > > size -= PAGE_SIZE;
> > > tmpva += PAGE_SIZE;
> > > - pa += PAGE_SIZE;
> > > }
> > > invltlb();
> > >
> > > Excuse me while I go outside and shoot myself.
> >
> > Hahahaha!
> >
> > Glad to see you have fixed them. :)
>
> Unfortunately, there are still more problems. :-(
> I've still got to find this one though:
>
> TPTE at 0xbfca01f0 IS ZERO @ VA 2807c000
> panic: bad peter
>
> db> trace
> panic(c043087f,bfca01f0,2807c000,1,c040e9d7) at panic+0x84
> pmap_remove_pages(c15d6ed0,0,bfc00000,115,c028aee0) at pmap_remove_pages+0x9c
> exit1(c15d5180,8b,c6,c24a0d04,0) at exit1+0x4f0
> sigexit(c15d5180,b,c040fbb1,6e9,0) at sigexit+0x1b9
> postsig(b,0,c0413100,e4,400) at postsig+0x11b
> ast(d3aa5d48) at ast+0x328
> doreti_ast() at doreti_ast+0x1a
ARGH! I think I found this one too. :-/
I think the fix [relative to the patch] is:
pmap_pte_quick()
...
/* are we current address space or kernel? */
if (pmap == kernel_pmap || frame == (PTDpde & PG_FRAME))
return PTmap + index;
newpf = pde & PG_FRAME;
if (((*PMAP1) & PG_FRAME) != newpf) {
*PMAP1 = newpf | PG_RW | PG_V;
- pmap_invalidate_page(pmap, (vm_offset_t) PADDR1);
+ pmap_invalidate_page(kernel_pmap, (vm_offset_t) PADDR1);
}
return PADDR1 + (index & (NPTEPG - 1));
*blush*. (read pmap_invalidate_page() in the diff to see why)
Cheers,
-Peter
--
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
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