Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
| From | Michael S <already5chosen@yahoo.com> |
|---|---|
| Newsgroups | comp.arch |
| Subject | Re: Performance of xchg reg,reg |
| Date | 2026-10-18 20:47 +0300 |
| Organization | A noiseless patient Spider |
| Message-ID | <20261018204738.00006b41@yahoo.com> (permalink) |
| References | (4 earlier) <11b0bd3$b5b$1@reader2.panix.com> <1792265982-5857@newsgrouper.org> <2026Oct18.170823@mips.complang.tuwien.ac.at> <20261018184318.00000bee@yahoo.com> <2026Oct18.185726@mips.complang.tuwien.ac.at> |
On Sun, 18 Oct 2026 16:57:26 GMT
anton@mips.complang.tuwien.ac.at (Anton Ertl) wrote:
> Michael S <already5chosen@yahoo.com> writes:
> >On Sun, 18 Oct 2026 15:08:23 GMT
> >anton@mips.complang.tuwien.ac.at (Anton Ertl) wrote:
> >> I don't think that's the issue here. They just did not limit the
> >> sentence "The XCHG instruction always asserts the LOCK# signal
> >> regardless of the presence or absence of the LOCK prefix." to XCHG
> >> instructions with memory operands. That would be easy to fix, but
> >> they did not. And Chris M. Thomasson understood it as including
> >> XCHG reg, reg.
> ...
> >Frankly, I don't understand what both you and Dan Cross are talking
> >about.
> >I don't see how sentence from Intel's manual ("If a memory operand is
> >referenced, the processor=E2=80=99s locking protocol is automatically
> >implemented for the duration of the exchange operation, regardless of
> >the presence or absence of the LOCK prefix or of the value of the
> >IOPL") or sentence from AMD's manual ("If either operand references
> >memory, the processor locks automatically, whether or not the LOCK
> >prefix is used and independently of the value of IOPL.") can be
> >pssibly misunderstood.
>
> Chris M. Thomasson wrote in <11arg45$2p70p$1@dont-email.me>:
> |Well, for some reason the LOCK prefix is implied for XCHG.
>
> Given that the thread up to that point was aboyt XCHG reg, reg (and
> according to the subject it still is), he seems to be an example that
> what Intel wrote about XCHG and LOCK can be misunderstood. I looked
> at the documentation and cited the relevant sentences in
> <2026Oct16.075055@mips.complang.tuwien.ac.at>; most occurences clearly
> refer only to XCHG where one operand is in memory. The exception is:
>
> |The XCHG instruction always asserts the LOCK# signal regardless of
> the |presence or absence of the LOCK prefix.
>
What is a source of this? Intel, AMD or somebody else?
> And actually all the stuff about XCHG with memory operands does not
> contradict this sentence. It could be understood as meaning that
> while all the other aspects of locking don't apply to "XCHG reg, reg",
> the assertion of the LOCK# signal still has to occur, and that's why
> Intel processors implement a slow XCHG reg, reg. I don't think that's
> what Intel intends and implements, but that's what a reading of their
> manual implies.
>
> - anton
Somehow, it does not imply it to me.
Back to comp.arch | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-13 08:43 +0000
Re: Performance of xchg reg,reg Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-14 00:23 +0000
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-14 07:00 +0000
Re: Performance of xchg reg,reg MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-14 22:35 +0000
Re: Performance of xchg reg,reg Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-14 23:07 +0000
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-15 06:05 +0000
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-15 07:06 +0000
Re: Performance of xchg reg,reg EricP <ThatWouldBeTelling@thevillage.com> - 2026-10-16 09:47 -0400
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-16 16:04 +0000
Re: Performance of xchg reg,reg Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-17 05:46 +0000
Re: Performance of xchg reg,reg Michael S <already5chosen@yahoo.com> - 2026-10-14 22:29 +0300
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-15 14:21 -0700
Re: Performance of xchg reg,reg Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-15 21:42 +0000
Re: Performance of xchg reg,reg Terje Mathisen <terje.mathisen@tmsw.no> - 2026-10-16 14:45 +0200
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-16 05:50 +0000
Re: Performance of xchg reg,reg Michael S <already5chosen@yahoo.com> - 2026-10-16 11:34 +0300
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-16 18:23 +0000
Re: Performance of xchg reg,reg scott@slp53.sl.home (Scott Lurndal) - 2026-10-16 20:48 +0000
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-16 14:28 -0700
Re: Performance of xchg reg,reg Thomas Koenig <tkoenig@netcologne.de> - 2026-10-17 09:48 +0000
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-17 02:50 +0000
Re: Performance of xchg reg,reg MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-17 17:11 +0000
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-17 17:31 +0000
Re: Performance of xchg reg,reg MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-17 19:39 +0000
Re: Performance of xchg reg,reg Michael S <already5chosen@yahoo.com> - 2026-10-17 23:20 +0300
Re: Documentation (was Re: Performance of xchg reg,reg) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-17 20:54 +0000
Re: Documentation (was Re: Performance of xchg reg,reg) George Neuner <gneuner2@comcast.net> - 2026-10-18 09:45 -0400
Algol 68 (was: Documentation (was Re: Performance of xchg reg,reg)) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-18 14:08 +0000
Re: Algol 68 (was: Documentation (was Re: Performance of xchg reg,reg)) quadibloc@invalid.com (John Savard) - 2026-10-19 00:09 +0000
Re: Algol 68 (was Re: Documentation) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-19 01:46 +0000
Re: Algol 68 (was Re: Documentation) quadibloc@invalid.com (John Savard) - 2026-10-21 14:15 +0000
Re: Algol 68 (was Re: Documentation) Niklas Holsti <niklas.holsti@tidorum.invalid> - 2026-10-21 18:34 +0300
Re: Algol 68 (was Re: Documentation) quadibloc@invalid.com (John Savard) - 2026-10-21 19:38 +0000
Re: Algol 68 (was Re: Documentation) aph@littlepinkcloud.invalid - 2026-10-22 09:51 +0000
Re: Algol 68 (was Re: Documentation) Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-10-22 14:15 -0700
Re: Algol 68 (was Re: Documentation) scott@slp53.sl.home (Scott Lurndal) - 2026-10-23 14:08 +0000
Re: PL/I, was Algol 68 (was: Documentation (was Re: Performance of xchg reg,reg)) John Levine <johnl@taugh.com> - 2026-10-19 03:24 +0000
Re: PL/I, was Algol 68 (was: Documentation (was Re: Performance of xchg reg,reg)) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-19 05:34 +0000
Re: Algol 68 Stefan Monnier <monnier@iro.umontreal.ca> - 2026-10-18 23:34 -0400
Re: Documentation (was Re: Performance of xchg reg,reg) quadibloc@invalid.com (John Savard) - 2026-10-19 00:18 +0000
Re: Documentation (was Re: Performance of xchg reg,reg) cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-19 01:52 +0000
Re: Documentation (was Re: Performance of xchg reg,reg) George Neuner <gneuner2@comcast.net> - 2026-10-19 14:50 -0400
Re: Documentation (was Re: Performance of xchg reg,reg) cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-20 02:05 +0000
Re: Algol 68 (was Re: Documentation) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-19 01:54 +0000
Re: Documentation (was Re: Performance of xchg reg,reg) Thomas Koenig <tkoenig@netcologne.de> - 2026-10-19 07:44 +0000
Re: Documentation (was Re: Performance of xchg reg,reg) Stefan Monnier <monnier@iro.umontreal.ca> - 2026-10-19 12:24 -0400
Re: Documentation (was Re: Performance of xchg reg,reg) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-18 17:48 +0000
Re: Performance of xchg reg,reg George Neuner <gneuner2@comcast.net> - 2026-10-18 08:59 -0400
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-18 15:08 +0000
Re: Performance of xchg reg,reg Michael S <already5chosen@yahoo.com> - 2026-10-18 18:43 +0300
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-18 16:57 +0000
Re: Performance of xchg reg,reg Michael S <already5chosen@yahoo.com> - 2026-10-18 20:47 +0300
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-18 18:07 +0000
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-18 21:04 +0000
Re: Performance of xchg reg,reg Stefan Monnier <monnier@iro.umontreal.ca> - 2026-10-18 23:43 -0400
Re: Performance of xchg reg,reg Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2026-10-19 06:57 -0700
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-19 14:27 -0700
Re: Performance of xchg reg,reg Stefan Monnier <monnier@iro.umontreal.ca> - 2026-10-20 10:00 -0400
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-20 02:00 +0000
Re: Performance of xchg reg,reg scott@slp53.sl.home (Scott Lurndal) - 2026-10-20 14:09 +0000
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-20 16:44 -0700
Re: Performance of xchg reg,reg Stefan Monnier <monnier@iro.umontreal.ca> - 2026-10-20 10:05 -0400
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-20 19:56 +0000
Re: Performance of xchg reg,reg anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-10-22 10:54 +0000
Re: Performance of xchg reg,reg Michael S <already5chosen@yahoo.com> - 2026-10-22 22:11 +0300
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-18 17:40 +0000
Re: Performance of xchg reg,reg Michael S <already5chosen@yahoo.com> - 2026-10-18 20:54 +0300
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-18 18:25 +0000
Re: Performance of xchg reg,reg MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-18 18:01 +0000
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-18 17:59 +0000
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-18 17:09 +0000
Re: Performance of xchg reg,reg EricP <ThatWouldBeTelling@thevillage.com> - 2026-10-18 12:31 -0400
Re: Performance of xchg reg,reg cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-18 17:47 +0000
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-18 12:27 -0700
Re: Performance of xchg reg,reg EricP <ThatWouldBeTelling@thevillage.com> - 2026-10-19 09:38 -0400
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-19 14:08 -0700
Re: Performance of xchg reg,reg Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-19 21:21 +0000
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-19 14:26 -0700
Re: Performance of xchg reg,reg Joseph Seigh <jseigh_es00@xemaps.com> - 2026-10-19 19:17 -0400
Re: Performance of xchg reg,reg "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-19 22:41 -0700
Re: Performance of xchg reg,reg MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-10-20 16:45 +0000
csiph-web