Re: Memory ordering

Liste des GroupesRevenir à c arch 
Sujet : Re: Memory ordering
De : chris.m.thomasson.1 (at) *nospam* gmail.com (Chris M. Thomasson)
Groupes : comp.arch
Date : 31. Jul 2024, 09:01:45
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <v8cr19$1g8jb$3@dont-email.me>
References : 1 2 3 4 5 6 7 8 9 10 11 12
User-Agent : Mozilla Thunderbird
On 7/31/2024 1:00 AM, Chris M. Thomasson wrote:
On 7/31/2024 12:57 AM, Chris M. Thomasson wrote:
On 7/30/2024 2:47 AM, Michael S wrote:
On Mon, 29 Jul 2024 20:43:47 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:
>
On Mon, 29 Jul 2024 20:08:10 +0000, Chris M. Thomasson wrote:
>
On 7/29/2024 10:49 AM, MitchAlsup1 wrote:
[...]
A MEMBAR dropped into the pipeline, when nothing is speculative,
takes no more time than an integer ADD. Only when there is
speculation does it have to take time to relax the speculation.
>
I am wondering if you were ever aware of the "danger zone" wrt
putting a MEMBAR instruction in a memory delay slot over on the
SPARC? The docs explicitly said not to do it. I guess it can cause
some interesting memory order "issues" that might allow a running
system to last for say, five years before crashing at a random
time... Yikes!
>
Which, btw, is why one should exhaustively test atomic codes before
putting it production. You do not want to chase down a memory ordering
issue that occurs, in production, less than once a month.
>
I did a lot of programming on SPARCs and never needed a MEMBAR....
but the OS guys used them like they were "free".
>
>
Did you do programming on SPARC in RMO mode?
According to my understanding, RMO mode existed only on a couple of
SPARC CPU models (UltraSparc and UltraSparc-II) and was activated only
by OSes others than Solaris. Possibly, only by Linux.
>
All sorts of things were dangerous in the delay slot of a branch,
not the least of which was another branch.
>
>
Chris M. Thomasson wrote "memory delay slot".
>
I was not good to put a MEMBAR instruction in any branch delay slot, or any delay slot...
[...]
 Damn typos!
 It was explicitly mentioned in some docs I read around 18'ish years ago, irrc, to never put a MEMBAR instruction in a branch delay slot.
 
This was back when I getting a feel for SPARC assembly language.

Date Sujet#  Auteur
24 Jul 24 * Arguments for a sane ISA 6-years later63MitchAlsup1
25 Jul 24 `* Re: Arguments for a sane ISA 6-years later62BGB
25 Jul 24  +* Re: Arguments for a sane ISA 6-years later57Chris M. Thomasson
26 Jul 24  i`* Re: Arguments for a sane ISA 6-years later56Anton Ertl
26 Jul 24  i +* Re: Arguments for a sane ISA 6-years later20BGB
29 Jul 24  i i`* Re: Arguments for a sane ISA 6-years later19Anton Ertl
29 Jul 24  i i +* Intel overvoltage (was: Arguments for a sane ISA 6-years later)2Thomas Koenig
29 Jul 24  i i i`- Re: Intel overvoltage1BGB
29 Jul 24  i i `* Re: Arguments for a sane ISA 6-years later16BGB
30 Jul 24  i i  `* Re: Arguments for a sane ISA 6-years later15Anton Ertl
30 Jul 24  i i   `* Re: Arguments for a sane ISA 6-years later14BGB
30 Jul 24  i i    +* Re: Arguments for a sane ISA 6-years later2Chris M. Thomasson
31 Jul 24  i i    i`- Re: Arguments for a sane ISA 6-years later1BGB
1 Aug 24  i i    `* Re: Arguments for a sane ISA 6-years later11Anton Ertl
1 Aug 24  i i     +- Re: Arguments for a sane ISA 6-years later1Michael S
1 Aug 24  i i     +* Re: Arguments for a sane ISA 6-years later8MitchAlsup1
1 Aug 24  i i     i+- Re: Arguments for a sane ISA 6-years later1Michael S
2 Aug 24  i i     i`* Re: Arguments for a sane ISA 6-years later6MitchAlsup1
2 Aug 24  i i     i +- Re: Arguments for a sane ISA 6-years later1Michael S
4 Aug 24  i i     i `* Re: Arguments for a sane ISA 6-years later4MitchAlsup1
5 Aug 24  i i     i  `* Re: Arguments for a sane ISA 6-years later3Stephen Fuld
5 Aug 24  i i     i   `* Re: Arguments for a sane ISA 6-years later2Stephen Fuld
5 Aug 24  i i     i    `- Re: Arguments for a sane ISA 6-years later1MitchAlsup1
1 Aug 24  i i     `- Re: Arguments for a sane ISA 6-years later1BGB
26 Jul 24  i +* Re: Arguments for a sane ISA 6-years later20MitchAlsup1
27 Jul 24  i i+- Re: Arguments for a sane ISA 6-years later1BGB
29 Jul 24  i i`* Memory ordering (was: Arguments for a sane ISA 6-years later)18Anton Ertl
29 Jul 24  i i +* Re: Memory ordering15MitchAlsup1
29 Jul 24  i i i+* Re: Memory ordering6Chris M. Thomasson
29 Jul 24  i i ii`* Re: Memory ordering5MitchAlsup1
30 Jul 24  i i ii `* Re: Memory ordering4Michael S
31 Jul 24  i i ii  `* Re: Memory ordering3Chris M. Thomasson
31 Jul 24  i i ii   `* Re: Memory ordering2Chris M. Thomasson
31 Jul 24  i i ii    `- Re: Memory ordering1Chris M. Thomasson
30 Jul 24  i i i`* Re: Memory ordering8Anton Ertl
30 Jul 24  i i i +* Re: Memory ordering2Chris M. Thomasson
30 Jul 24  i i i i`- Re: Memory ordering1Chris M. Thomasson
31 Jul 24  i i i `* Re: Memory ordering5MitchAlsup1
31 Jul 24  i i i  +- Re: Memory ordering1Chris M. Thomasson
1 Aug 24  i i i  `* Re: Memory ordering3Anton Ertl
1 Aug 24  i i i   `* Re: Memory ordering2MitchAlsup1
2 Aug 24  i i i    `- Re: Memory ordering1Anton Ertl
29 Jul 24  i i `* Re: Memory ordering2Chris M. Thomasson
30 Jul 24  i i  `- Re: Memory ordering1Chris M. Thomasson
29 Jul 24  i +* Re: Arguments for a sane ISA 6-years later13Chris M. Thomasson
29 Jul 24  i i+* Re: Arguments for a sane ISA 6-years later9BGB
29 Jul 24  i ii`* Re: Arguments for a sane ISA 6-years later8Chris M. Thomasson
29 Jul 24  i ii +- Re: Arguments for a sane ISA 6-years later1Chris M. Thomasson
29 Jul 24  i ii +* Re: Arguments for a sane ISA 6-years later2BGB
29 Jul 24  i ii i`- Re: Arguments for a sane ISA 6-years later1Chris M. Thomasson
30 Jul 24  i ii `* Re: Arguments for a sane ISA 6-years later4jseigh
30 Jul 24  i ii  `* Re: Arguments for a sane ISA 6-years later3Chris M. Thomasson
31 Jul 24  i ii   `* Re: Arguments for a sane ISA 6-years later2jseigh
31 Jul 24  i ii    `- Re: Arguments for a sane ISA 6-years later1Chris M. Thomasson
29 Jul 24  i i+- Memory ordering (was: Arguments for a sane ISA 6-years later)1Anton Ertl
29 Jul 24  i i`* Re: Arguments for a sane ISA 6-years later2MitchAlsup1
29 Jul 24  i i `- Re: Arguments for a sane ISA 6-years later1BGB
6 Aug 24  i `* Re: Arguments for a sane ISA 6-years later2Chris M. Thomasson
6 Aug 24  i  `- Re: Arguments for a sane ISA 6-years later1Chris M. Thomasson
26 Jul 24  `* Re: Arguments for a sane ISA 6-years later4MitchAlsup1
27 Jul 24   +- Re: Arguments for a sane ISA 6-years later1BGB
28 Jul 24   `* Re: Arguments for a sane ISA 6-years later2Paul A. Clayton
28 Jul 24    `- Re: Arguments for a sane ISA 6-years later1MitchAlsup1

Haut de la page

Les messages affichés proviennent d'usenet.

NewsPortal