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| From | Paul <nospam@needed.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Does each core of 8-core Intel processor has an independent floating X87 unit? |
| Date | 2015-04-05 14:31 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <mfrv11$tui$1@dont-email.me> (permalink) |
| References | <0c864744-32bf-4ce9-8b2e-f2a842fec7bb@googlegroups.com> |
Weng Tianxiang wrote:
> Hi,
> Does each core of 8-core Intel processor has an independent floating X87 unit?
>
> Here are some texts from Intel latest datasheet:
>
> Intel(R) Core(tm) i7 Processor Family for LGA2011-v3 Socket
> Datasheet - Volume 1 of 2
>
> Processor Feature Details
> *Up to 8 execution cores
> *Each core supports two threads (Intel(R) Hyper-Threading Technology)
> *32 KB instruction and 32 KB data first-level cache (L1) for each core
> *256 KB shared instruction/data mid-level (L2) cache for each core
> *Up to 15 MB last level cache (LLC): up to 2.5 MB per core instruction/data last level cache (LLC), shared among all cores.
>
> 5.2 X87 FPU INSTRUCTIONS
> The x87 FPU instructions are executed by the processor's x87 FPU. These instructions operate on floating-point, integer, and binary-coded decimal (BCD) operands. For more detail on x87 FPU instructions, see Chapter 8, "Programming with the x87 FPU."
>
> These instructions are divided into the following subgroups: data transfer, load constants, and FPU control instructions.
>
> From above text I have a feeling that all 8 execution cores share the same X87 FPU unit.
>
> Am I right or not?
>
> Is there anyone who has real experiences with X87 FPU unit?
>
> Thank you.
>
> Weng
Take a 4C 8T (hyperthreaded) processor, like this one.
http://ark.intel.com/products/80807/Intel-Core-i7-4790K-Processor-8M-Cache-up-to-4_40-GHz
This would be a drawing of the processor. I do not know the
details of the FPU section, whether there are one or two
units, how fast they can retire instructions. So this is only
a rough approximation.
Logical Logical Logical Logical Logical Logical Logical Logical
Core 0 Core 1 Core 2 Core 3 Core 4 Core 5 Core 6 Core 7
\ / \ / \ / \ /
Physical Physical Physical Physical
Dispatch -- FPU Dispatch -- FPU dispatch -- FPU Dispatch -- FPU
| |
(retired (retired (retired (retired
instructions) instructions) instructions) instructions)
Only enough of the architecture is shown in this diagram,
to point out that the processor *actually* only has 4 cores (not 8),
and a dedicated FPU is associated with each core. I do not
know the exact details of that FPU.
Hyperthreading is an overlay on top of that, where core state
is preserved on a stall, and the core can work on a second task
which is not stalled. Thus squeezing 10% more performance from the
four cores. In Windows, you see eight performance graphs,
but it's all a sham. You're seeing 4.4 cores of performance,
graphed in 8 graph columns.
Paul
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Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-05 06:50 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Noob <root@127.0.0.1> - 2015-04-05 17:17 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 17:35 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:21 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 18:40 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:56 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 10:08 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 13:17 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:10 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 10:26 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 23:40 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Bartc <bc@freeuk.com> - 2015-04-07 23:06 +0100
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-08 01:23 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 23:15 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 20:16 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-08 09:27 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-08 09:44 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 19:37 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 18:50 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-05 22:29 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 23:09 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 01:54 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 07:44 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:16 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 03:32 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 12:48 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Richard Heathfield <rjh@cpax.org.uk> - 2015-04-07 11:57 +0100
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 13:33 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 15:21 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-07 17:15 +0000
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Tim Prince <tprince@computer.org> - 2015-04-07 14:21 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:08 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 15:27 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Noob <root@127.0.0.1> - 2015-04-05 19:04 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 19:38 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 10:46 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:12 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 09:51 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 12:18 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? jacobnavia <jacob@jacob.remcomp.fr> - 2015-04-06 01:30 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 19:27 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? christian.bau@cbau.wanadoo.co.uk - 2015-04-07 23:58 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-08 08:08 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-06 03:36 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:27 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 10:39 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? christian.bau@cbau.wanadoo.co.uk - 2015-04-07 23:47 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:04 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 18:20 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:43 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-05 20:28 +0000
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-05 14:46 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 15:01 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:17 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-05 14:31 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 11:01 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-05 22:34 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-05 23:39 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 02:06 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 08:57 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:38 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 16:30 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-06 17:10 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Ian Collins <ian-news@hotmail.com> - 2015-04-07 10:16 +1200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-07 02:23 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 17:36 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 17:41 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 20:09 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Richard Damon <Richard@Damon-Family.org> - 2015-04-06 22:44 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 11:11 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-06 08:04 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:43 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-06 14:52 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 17:09 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-06 11:11 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:47 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-06 17:15 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 03:41 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Ian Collins <ian-news@hotmail.com> - 2015-04-07 21:19 +1200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-07 10:37 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Tim Prince <tprince@computer.org> - 2015-04-07 12:13 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-09 12:34 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-07 10:48 -0500
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