Article: Knights Landing CPU Speculation
By: Patrick Chase (patrickjchase.delete@this.hp.com), November 23, 2013 4:18 pm
Room: Moderated Discussions
none (none.delete@this.none.com) on November 18, 2013 3:59 am wrote:
> Nice article as usual :-)
>
> Just one comment:
>
> "Moreover, the L1D in Knights Corner was 32KB and 8-way associative to work with 4
> threads – the 6 way associativity in Silvermont is simply insufficient and would cause
> excessive conflicts."
>
> My understanding is that Intel use 6/8 ways no because of MT but to prevent having to
> use hardware alias handling for 4KB pages.
I think that's correct - Every Intel x86 core from the 486 on has had a VIPT L1 D$, with set size less than or equal to the smallest x86 page size of 4 KB. For example, the Core2 did not have SMT but did have an 8-way L1 D$.
With that said, it doesn't really diminish or argue against David's point. Regardless of how Intel got to high associativity to begin with, they wouldn't want to back off on that attribute in such an aggressively multi-threaded core.
> Nice article as usual :-)
>
> Just one comment:
>
> "Moreover, the L1D in Knights Corner was 32KB and 8-way associative to work with 4
> threads – the 6 way associativity in Silvermont is simply insufficient and would cause
> excessive conflicts."
>
> My understanding is that Intel use 6/8 ways no because of MT but to prevent having to
> use hardware alias handling for 4KB pages.
I think that's correct - Every Intel x86 core from the 486 on has had a VIPT L1 D$, with set size less than or equal to the smallest x86 page size of 4 KB. For example, the Core2 did not have SMT but did have an 8-way L1 D$.
With that said, it doesn't really diminish or argue against David's point. Regardless of how Intel got to high associativity to begin with, they wouldn't want to back off on that attribute in such an aggressively multi-threaded core.
Topic | Posted By | Date |
---|---|---|
Knights Landing CPU Speculation | David Kanter | 2013/11/18 03:03 AM |
Knights Landing CPU Speculation | none | 2013/11/18 03:59 AM |
Knights Landing CPU Speculation | Patrick Chase | 2013/11/23 04:18 PM |
Knights Landing CPU Speculation | 2013/11/26 02:20 AM | |
Over 2,000 mm^2 of eDRAM??? | Mark Roulo | 2013/11/26 10:28 AM |
Over 2,000 mm^2 of eDRAM??? | David Kanter | 2013/11/26 12:09 PM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/26 12:21 PM |
Over 2,000 mm^2 of eDRAM??? | tarlinian | 2013/11/26 12:50 PM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/26 02:07 PM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/26 02:09 PM |
Over 2,000 mm^2 of eDRAM??? | aaron spink | 2013/11/26 04:03 PM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/27 12:42 AM |
Over 2,000 mm^2 of eDRAM??? | aaron spink | 2013/11/27 11:31 AM |
Over 2,000 mm^2 of eDRAM??? | David Kanter | 2013/11/26 05:25 PM |
Over 2,000 mm^2 of eDRAM??? | tarlinian | 2013/11/26 08:01 PM |
Over 2,000 mm^2 of eDRAM??? | Eric | 2013/11/27 03:54 AM |
eDRAM is DRAM in a logic-oriented process | Paul A. Clayton | 2013/11/27 08:10 AM |
Knights Landing CPU Speculation | James | 2013/11/18 06:26 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/18 03:57 PM |
Knights Landing CPU Speculation | Urban Novak | 2013/11/19 01:49 AM |
Knights Landing CPU Speculation | none | 2013/11/19 02:19 AM |
Knights Landing CPU Speculation | Eric | 2013/11/19 08:48 PM |
Total GPGPU/Xeon Phi market maybe ~ $500M/year ... | Mark Roulo | 2013/11/20 11:35 AM |
Knights Landing CPU Speculation | Wes Felter | 2013/11/19 01:06 PM |
Knights Landing CPU Speculation | Michael S | 2013/11/19 01:49 PM |
Knights Landing CPU Speculation | Eric | 2013/11/18 01:17 PM |
Knights Landing CPU Speculation | Daniel | 2013/11/19 03:28 AM |
Knights Landing CPU Speculation | Eric | 2013/11/19 08:36 PM |
HPC guys score FLOPS non-obviously | Mark Roulo | 2013/11/20 11:43 AM |
3-TFlops-DGEMM | Michael S | 2013/11/20 11:59 AM |
3-TFlops-DGEMM | Mark Roulo | 2013/11/20 01:22 PM |
3-TFlops-DGEMM | Daniel | 2013/11/20 02:04 PM |
3-TFlops-DGEMM | Eric | 2013/11/21 02:28 AM |
3-TFlops-DGEMM | Michael S | 2013/11/21 06:48 AM |
3-TFlops-DGEMM | RecessionCone | 2013/11/21 12:13 PM |
3-TFlops-DGEMM | Michael S | 2013/11/21 03:34 PM |
3-TFlops-DGEMM | Eric | 2013/11/22 03:10 AM |
3-TFlops-DGEMM | Michael S | 2013/11/22 05:41 AM |
A (not very sensible) alternative: FMADD + FADD | Paul A. Clayton | 2013/11/22 09:19 AM |
3-TFlops-DGEMM | Sylvain Collange | 2013/11/24 03:37 AM |
3-TFlops-DGEMM | Michael S | 2013/11/24 07:06 AM |
3-TFlops-DGEMM | Sylvain Collange | 2013/11/24 10:28 AM |
HPC guys score FLOPS non-obviously | Patrick Chase | 2013/11/23 03:58 PM |
Knights Landing CPU Speculation | Paul Caheny | 2013/11/18 02:25 PM |
Knights Landing CPU Speculation | Konrad Schwarz | 2013/11/19 01:24 AM |
Knights Landing CPU Speculation | Amiba Gelos | 2013/11/19 08:36 PM |
Knights Landing CPU Speculation | David Kanter | 2013/11/20 10:52 AM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/21 03:12 PM |
Knights Landing CPU Speculation | Amiba Gelos | 2013/11/21 06:14 PM |
Knights Landing CPU Speculation | Patrick Chase | 2013/11/23 04:33 PM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/25 12:29 PM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/25 01:05 PM |
Knights Landing CPU Speculation | Patrick Chase | 2013/11/25 01:22 PM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/26 11:11 AM |
Knights Landing CPU Speculation | Eric | 2013/11/26 04:05 AM |
Knights Landing CPU Speculation | Eric | 2013/11/26 04:15 AM |
Knights Landing CPU Speculation | none | 2013/11/26 04:33 AM |
Knights Landing CPU Speculation | Eric | 2013/11/26 07:30 PM |
Knights Landing CPU Speculation | Eric | 2013/11/26 07:34 PM |
What is MCDRAM? | anon | 2013/11/26 09:58 PM |
What is MCDRAM? | none | 2013/11/27 02:00 AM |
What is MCDRAM? | Klimax | 2013/11/27 03:19 AM |
Knights Landing CPU Speculation | Klimax | 2013/11/27 12:06 AM |
Knights Landing CPU Speculation | Klimax | 2013/11/27 12:05 AM |
Knights Landing CPU Speculation | anon | 2013/11/26 06:53 AM |
Knights Landing CPU Speculation | none | 2013/11/26 07:20 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/26 09:06 AM |
Knights Landing CPU Speculation | none | 2013/11/26 10:18 AM |
Knights Landing CPU Speculation | Eric Bron | 2013/11/26 02:21 PM |
Knights Landing CPU Speculation | Eric Bron | 2013/11/26 02:27 PM |
Knights Landing CPU Speculation | none | 2013/11/26 03:26 PM |
Knights Landing CPU Speculation | anon | 2013/11/26 06:42 PM |
Knights Landing CPU Speculation | none | 2013/11/27 02:08 AM |
Knights Landing CPU Speculation | anon | 2013/11/27 02:50 AM |
Knights Landing CPU Speculation | none | 2013/11/27 02:58 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/27 02:25 AM |
Knights Landing CPU Speculation | anon | 2013/11/27 03:32 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/27 04:08 AM |
Knights Landing CPU Speculation | Chung Leong | 2013/11/27 02:28 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/27 03:53 AM |
Knights Landing CPU Speculation | Chung Leong | 2013/11/27 02:03 PM |
BiG.LiTTLe for KNL? | Jeff K | 2013/11/22 07:17 AM |
BiG.LiTTLe for KNL? | Patrick Chase | 2013/11/23 03:54 PM |
BiG.LiTTLe for KNL? | Patrick Chase | 2013/11/23 04:01 PM |
Transactional memory | Patrick Chase | 2013/11/23 03:37 PM |
Transactional memory | Bhima | 2013/11/25 08:01 AM |
Transactional memory | Patrick Chase | 2013/11/25 12:52 PM |
Knights Landing CPU Speculation | Daniel | 2013/11/25 03:17 AM |
Knights Landing CPU Speculation | Klimax | 2013/11/25 04:12 AM |
Knights Landing CPU Speculation | none | 2013/11/25 05:05 AM |
Knights Landing CPU Speculation | Klimax | 2013/11/25 05:45 AM |
Knights Landing CPU Speculation | none | 2013/11/25 05:55 AM |
Knights Landing CPU Speculation | gmb | 2013/11/25 08:21 AM |