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From: Borislav Petkov <bp@alien8.de>
To: Willy Tarreau <w@1wt.eu>
Cc: Len Brown <lenb@kernel.org>, Andy Lutomirski <luto@kernel.org>,
	Florian Weimer <fweimer@redhat.com>,
	"Bae, Chang Seok" <chang.seok.bae@intel.com>,
	Dave Hansen <dave.hansen@intel.com>, X86 ML <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-abi@vger.kernel.org,
	"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>,
	Rich Felker <dalias@libc.org>, Kyle Huey <me@kylehuey.com>,
	Keno Fischer <keno@juliacomputing.com>
Subject: Re: Candidate Linux ABI for Intel AMX and hypothetical new related features
Date: Thu, 15 Apr 2021 07:47:13 +0200	[thread overview]
Message-ID: <20210415054713.GB6318@zn.tnic> (raw)
In-Reply-To: <20210415052938.GA2325@1wt.eu>

On Thu, Apr 15, 2021 at 07:29:38AM +0200, Willy Tarreau wrote:
> What Len is saying is that not being interested in a feature is not an
> argument for rejecting its adoption,

Oh, I'm not rejecting its adoption - no, don't mean that.

> which I'm perfectly fine with. But conversely not being interested in
> a feature is also an argument for insisting that its adoption doesn't
> harm other use cases (generally speaking, not this specific case
> here).

Pretty much.

What I'd like to see is 0-overhead for current use cases and only
overhead for those who want to use it. If that can't be done
automagically, then users should request it explicitly. So basically you
blow up the xsave buffer only for processes which want to do AMX.

And this brings the question about libraries which, if they start using
AMX by default - which doesn't sound like they will want to because AMX
reportedly will have only a limited? set of users - if libraries start
using it by default, then it better be worth the handling of the 8kb
buffer per process.

If not, this should also be requestable per process so that a simple
pipe in Linux:

<process> | grep | awk | sed ...

and so on is not penalized to allocate and handle by default 8kb for
*each* process' buffer in that pipe just because each is linking against
glibc which has detected AMX support in CPUID and is using it too for
some weird reason like some microbenchmark saying so.

All AFAIU, ofc.

But my initial question was on the "establishing" part and was asking
where we have established anything wrt AMX.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2021-04-15  5:47 UTC|newest]

Thread overview: 130+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-26 23:12 Candidate Linux ABI for Intel AMX and hypothetical new related features Andy Lutomirski
2021-03-26 23:18 ` Andy Lutomirski
2021-03-27  3:39   ` Len Brown
2021-03-27  9:14     ` Borislav Petkov
2021-03-27  9:58     ` Greg KH
2021-03-29 15:47       ` Len Brown
2021-03-29 16:38         ` Len Brown
2021-03-29 16:48           ` Florian Weimer
2021-03-29 18:14           ` Andy Lutomirski
2021-03-29 18:16         ` Andy Lutomirski
2021-03-29 22:38           ` Len Brown
2021-03-30  5:08             ` Andy Lutomirski
2021-03-30  5:50               ` Noah Goldstein
2021-03-30 17:01               ` Len Brown
2021-03-30 17:05                 ` Andy Lutomirski
2021-03-30 17:56                   ` Len Brown
2021-03-30 19:12                     ` Dave Hansen
2021-03-30 20:20                       ` Andy Lutomirski
2021-03-30 20:42                         ` Len Brown
2021-03-30 22:01                           ` David Laight
2021-03-31 16:31                             ` Len Brown
2021-03-31 16:53                               ` Andy Lutomirski
2021-03-31 21:42                                 ` Robert O'Callahan
2021-03-31 22:11                                   ` Len Brown
2021-03-31 22:28                                 ` Len Brown
2021-03-31 22:45                                   ` Andy Lutomirski
2021-04-09 20:52                                     ` Len Brown
2021-04-09 21:44                                       ` Andy Lutomirski
2021-04-11 19:07                                         ` Len Brown
2021-04-12  7:59                                           ` David Laight
2021-04-12 12:19                                           ` Borislav Petkov
2021-04-12 17:14                                           ` Sean Christopherson
2021-03-31 22:52                                   ` Borislav Petkov
2021-04-09 20:55                                     ` Len Brown
2021-03-28  0:53   ` Thomas Gleixner
2021-03-29  7:27     ` Peter Zijlstra
2021-03-29 15:06     ` Dave Hansen
2021-03-31  8:24 ` Borislav Petkov
     [not found] ` <87lf9nk2ku.fsf@oldenburg.str.redhat.com>
2021-04-12 14:31   ` Borislav Petkov
2021-04-12 14:38     ` Florian Weimer
2021-04-12 15:08       ` Borislav Petkov
2021-04-12 15:10       ` Andy Lutomirski
2021-04-12 15:21   ` Andy Lutomirski
2021-04-12 23:46     ` Len Brown
2021-04-13  0:17       ` Thomas Gleixner
2021-04-13  1:25         ` Len Brown
2021-04-13  3:43       ` Willy Tarreau
2021-04-13 19:51         ` Len Brown
2021-04-14  9:58           ` Borislav Petkov
2021-04-14 10:06             ` Willy Tarreau
2021-04-14 10:08               ` Borislav Petkov
2021-04-14 21:57             ` Len Brown
2021-04-15  4:43               ` Borislav Petkov
2021-04-15  5:29                 ` Willy Tarreau
2021-04-15  5:47                   ` Borislav Petkov [this message]
2021-04-16 22:05                     ` Len Brown
2021-04-19 14:14                       ` Borislav Petkov
2021-04-19 18:18                         ` Len Brown
2021-04-19 19:15                           ` Borislav Petkov
2021-04-19 21:33                             ` Len Brown
2021-04-19 21:58                               ` Borislav Petkov
2021-04-23 19:35                                 ` Len Brown
2021-04-23 19:57                                   ` Borislav Petkov
2021-05-02 15:27                                     ` Len Brown
2021-05-03  5:18                                       ` Florian Weimer
2021-05-03 13:43                                         ` Dave Hansen
2021-05-03 13:47                                           ` Florian Weimer
2021-05-03 14:14                                             ` Dave Hansen
2021-05-07 18:44                                           ` Thomas Gleixner
2021-05-07 18:50                                             ` Andy Lutomirski
2021-05-07 19:22                                               ` Thomas Gleixner
2021-05-08  9:45                                       ` Thomas Gleixner
2021-05-18 20:39                                         ` Len Brown
2021-05-19 23:29                                           ` Andy Lutomirski
2021-05-20 19:16                                             ` Len Brown
2021-05-17  9:45                                       ` Thomas Gleixner
2021-05-17  9:56                                         ` Florian Weimer
2021-05-17 10:18                                           ` Thomas Gleixner
2021-05-21 16:29                                           ` Len Brown
2021-05-17 13:49                                         ` Arjan van de Ven
2021-05-20 15:35                                         ` Len Brown
2021-05-20 20:54                                           ` Thomas Gleixner
2021-05-20 21:13                                             ` Dave Hansen
2021-05-20 21:41                                               ` Len Brown
2021-05-20 22:53                                                 ` Dave Hansen
2021-05-21  9:41                                                   ` Thomas Gleixner
2021-05-21 14:44                                                   ` Florian Weimer
2021-05-21 14:49                                                     ` Peter Zijlstra
2021-06-23 15:06                                                       ` Florian Weimer
2021-06-23 23:11                                                         ` Len Brown
2021-06-28 10:14                                                           ` Enrico Weigelt, metux IT consult
2021-06-28 12:49                                                             ` Florian Weimer
2021-06-30 12:22                                                               ` Enrico Weigelt, metux IT consult
2021-06-30 12:41                                                                 ` Willy Tarreau
2021-06-30 13:55                                                                 ` Arjan van de Ven
2021-06-30 15:20                                                                   ` Len Brown
2021-06-30 15:25                                                                   ` Enrico Weigelt, metux IT consult
2021-05-21 16:14                                                     ` Dave Hansen
2021-05-21 16:19                                                       ` Florian Weimer
2021-05-21 16:26                                                         ` Len Brown
2021-05-21 16:28                                                         ` Dave Hansen
2021-05-21 16:31                                                         ` Andy Lutomirski
2021-05-21 19:10                                                           ` Thomas Gleixner
2021-05-21 20:07                                                             ` Andy Lutomirski
2021-05-21 21:43                                                               ` Thomas Gleixner
2021-05-21 22:07                                                             ` Len Brown
2021-05-21 22:46                                                               ` Thomas Gleixner
2021-05-21 23:31                                                                 ` Len Brown
2021-05-22  7:16                                                                   ` Florian Weimer
2021-05-22 23:55                                                                     ` Andy Lutomirski
2021-05-21 23:06                                                               ` Dave Hansen
2021-05-21 23:08                                                                 ` Len Brown
2021-05-21 19:05                                                         ` Thomas Gleixner
2021-05-20 21:22                                             ` Len Brown
2021-05-20 21:41                                               ` Thomas Gleixner
2021-05-20 21:49                                                 ` Len Brown
2021-05-21  9:26                                                   ` Thomas Gleixner
2021-04-19 23:52                               ` Paul Eggert
2021-04-13 20:16       ` Andy Lutomirski
2021-04-13 22:47         ` Len Brown
2021-04-13 22:58           ` Andy Lutomirski
2021-04-14 21:48             ` Len Brown
2021-04-15 16:24               ` Andy Lutomirski
2021-04-15 17:00                 ` Dave Hansen
2021-04-15 17:38                   ` Andy Lutomirski
2021-04-16 21:54                 ` Len Brown
2021-04-16 22:03                   ` Andy Lutomirski
2021-04-16 22:10                     ` Len Brown
2021-04-16 22:14                       ` Andy Lutomirski
2021-04-17  1:57                         ` Len Brown

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