Date: Fri, 12 Jul 2002 02:29:41 -0700 From: Peter Wemm <peter@wemm.org> To: current@freebsd.org Subject: HEADS UP, beware of pmap changes. Message-ID: <20020712092941.B03793811@overcee.wemm.org>
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This is mostly a FYI because I do not expect major problems this time.
I have been extensively testing it in a handful of configurations.
I expect this to have bigger positive effects than are apparent from
the stats I quoted in the commit message from 'make world' for SMP systems,
especially for pentium/pentiumpro/2/3 systems. Pentium4 Xeon I am not sure
about.. it has a fast APIC subsystem, but the penalties for taking traps
etc are quite different.
There are a few more changes that I want to do over the next few days that
build on top of this - I backed a couple of things out of this change
that I thought were working but I didn't want to risk them yet.
If I've broken something new, please yell. I must confess that I have not
tried to use vm86 doscmd or anything perverse like that.
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
------- Forwarded Message
Date: Fri, 12 Jul 2002 00:56:11 -0700
From: Peter Wemm <peter@FreeBSD.org>
To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: cvs commit: src/sys/conf options.i386 options.pc98 src/sys/i386/i386 b
ios.c db_interface.c locore.s mp_machdep.c mpapic.c pmap.c support.s
vm86.c src/sys/i386/include cpufunc.h pmap.h smp.h src/sys/i386/isa a
pic_vector.s intr_machdep.h ...
peter 2002/07/12 00:56:11 PDT
Modified files:
sys/conf options.i386 options.pc98
sys/i386/i386 bios.c db_interface.c locore.s
mp_machdep.c mpapic.c pmap.c support.s
vm86.c
sys/i386/include cpufunc.h pmap.h smp.h
sys/i386/isa apic_vector.s intr_machdep.h
sys/kern subr_witness.c
Log:
Revive backed out pmap related changes from Feb 2002. The highlights are:
- It actually works this time, honest!
- Fine grained TLB shootdowns for SMP on i386. IPI's are very expensive,
so try and optimize things where possible.
- Introduce ranged shootdowns that can be done as a single IPI.
- PG_G support for i386
- Specific-cpu targeted shootdowns. For example, there is no sense in
globally purging the TLB cache for where we are stealing a page from
the local unshared process on the local cpu. Use pm_active to track
this.
- Add some instrumentation for the tlb shootdown code.
- Rip out SMP code from <machine/cpufunc.h>
- Try and fix some very bogus PG_G and PG_PS interactions that were bad
enough to cause vm86 bios calls to break. vm86 depended on our existing
bugs and this was the cause of the VESA panics last time.
- Fix the silly one-line error that caused the 'panic: bad pte' last time.
- Fix a couple of other silly one-line errors that should have caused more
pain than they did.
Some more work is needed:
- pmap_{zero,copy}_page[_idle]. These can be done without IPI's if we
have a hook in cpu_switch.
- The IPI handlers need some cleanup. I have a bogus %ds load that can
be avoided.
- APTD handling is rather bogus and appears to be a large source of
global TLB IPI shootdowns for no really good reason.
I see speedups of between 1.5% and ~4% on buildworlds in a while 1 loop.
I expect to see a bigger difference when there is significant pageout
activity or the system otherwise has memory shortages.
I have backed out a few optimizations that I had been using over the last
few days in order to be a little more conservative. I'll revisit these
again over the next few days as the dust settles.
New option: DISABLE_PG_G - In case I missed something.
Revision Changes Path
1.172 +2 -1 src/sys/conf/options.i386
1.147 +2 -1 src/sys/conf/options.pc98
1.54 +8 -7 src/sys/i386/i386/bios.c
1.66 +2 -2 src/sys/i386/i386/db_interface.c
1.158 +3 -21 src/sys/i386/i386/locore.s
1.188 +231 -23 src/sys/i386/i386/mp_machdep.c
1.59 +0 -3 src/sys/i386/i386/mpapic.c
1.337 +261 -249 src/sys/i386/i386/pmap.c
1.91 +0 -36 src/sys/i386/i386/support.s
1.47 +2 -0 src/sys/i386/i386/vm86.c
1.126 +93 -75 src/sys/i386/include/cpufunc.h
1.80 +5 -4 src/sys/i386/include/pmap.h
1.71 +9 -1 src/sys/i386/include/smp.h
1.84 +82 -5 src/sys/i386/isa/apic_vector.s
1.42 +13 -7 src/sys/i386/isa/intr_machdep.h
1.121 +3 -0 src/sys/kern/subr_witness.c
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