Intel Skylake / Kaby Lake

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vissarix

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Jun 12, 2015
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Does anyone have a vague idea on how much the Skylake X with his L1 1MB will improve performance?

I want to upgrade from current i7 2600k running at 4.8ghz to a 6/12 threads...Ryzen seems to have IB/Haswell IPC and that doesnt excite me to much...so my only choice would be Skylake X or wait another year...
 

lolfail9001

Golden Member
Sep 9, 2016
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Does anyone have a vague idea on how much the Skylake X with his L1 1MB will improve performance?
It is hard to have exact idea, cache overhauls are generally pretty messy. Though on napkin math, it should perform very slightly better than Skylake-S, but actually save on cache die space.
 
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Ajay

Diamond Member
Jan 8, 2001
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Well, SKL-X is not actually listed on that Wiki page.

I believe the grapevine has it as 1Mb of L2 cache per core for SKL-X, not L1. Previous chips had 256Kb.

Bit I don't think it is confirmed.
My bad. 1MB of L1 - holy smokes, that's nuts! Dog slow cache unless Intel really came up with something special.
 

Sweepr

Diamond Member
May 12, 2006
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Another Skylake-EP/SP (Purley) entry, this time Geekbench 3! This isn't the fastest model, that would be Xeon Platinum 8180 @ 2.5 GHz. :)

Intel Xeon Platinum 8170 @ 2.10 GHz


2 processors, 52 cores, 104 threads
L1 Instruction Cache 32 KB x 26
L1 Data Cache 32 KB x 26
L2 Cache 1024 KB x 26

Single-Core Score

4033
Multi-Core Score
138410

https://browser.primatelabs.com/geekbench3/8242239

Compared to the best GB3 Linux 64-bit score for Broadwell-EP (with 2x Xeon E5-2699 v4):

Single-Core Score
3827
Multi-Core Score
115935

https://browser.primatelabs.com/geekbench3/5958805
 
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Agent-47

Senior member
Jan 17, 2017
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Does anyone have a vague idea on how much the Skylake X with his L1 1MB will improve performance?

I want to upgrade from current i7 2600k running at 4.8ghz to a 6/12 threads...Ryzen seems to have IB/Haswell IPC and that doesnt excite me to much...so my only choice would be Skylake X or wait another year...
Marginal at best. These tests were done using 2c2t on same generation of Intel but with different L3 side. While L2 is a bit faster, overall gain will be similar as these cases add more amount.
 
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Mar 10, 2006
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It was obvious Power 9 had no long term future once they started pushing Open POWER.
POWER is dead, which is sad because it is technically competent, but it's hard to beat x86/Intel here, and x86's future is much more certain in the datacenter than POWER's is.
 

DrMrLordX

Lifer
Apr 27, 2000
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I wouldn't count out POWER yet, but IBM was clearly hedging their bets.

Nvidia will probably do more than anyone to keep POWER alive (outside of IBM themselves).
 
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SAAA

Senior member
May 14, 2014
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Marginal at best. These tests were done using 2c2t on same generation of Intel but with different L3 side. While L2 is a bit faster, overall gain will be similar as these cases add more amount.
Well considering nowadays IPC gains if quadrupling L3 can benefit games ~10% it bodes very well for Skylake-E: 4 times the L2 might be worth a full tock by itself... :eek:
 
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mikk

Platinum Member
May 15, 2012
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Marginal at best. These tests were done using 2c2t on same generation of Intel but with different L3 side. While L2 is a bit faster, overall gain will be similar as these cases add more amount.
L2 a bit faster? Did you test it or how can you say this? Intel changed the cache structure, you have no clue how it performs based on a current available Intel CPU. Also when you say L2 cache is a bit faster, you are way off even based on an available CPU.

https://forums.aida64.com/topic/2864-i7-5775c-l4-cache-performance/

L2 Read a doubling, Copy 66% faster, latency 4x faster.
 

Agent-47

Senior member
Jan 17, 2017
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L2 a bit faster? Did you test it or how can you say this? Intel changed the cache structure, you have no clue how it performs based on a current available Intel CPU. Also when you say L2 cache is a bit faster, you are way off even based on an available CPU.

https://forums.aida64.com/topic/2864-i7-5775c-l4-cache-performance/

L2 Read a doubling, Copy 66% faster, latency 4x faster.
???
I can say because i read the report.

You sound confident that these are not "current cpus". Lol.

Its haswell CPUs.

Lol. L2 may be faster, but the moment you increase the size of L2, its latency increases more drastically, so yes, gain will be marginal at best. go read the reviews of Athlon64 CPUs with different cache sizes. its "old" but the principle stays the same.

and what are you going to do, increase L2 from 256 kb/core to 8MB/core? funny!

And no. I did not do these test. You need to go chill. read the configs
 
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JoeRambo

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Jun 13, 2013
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???

Lol. L2 may be faster, but the moment you increase the size of L2, its latency increases more drastically, so yes, gain will be marginal at best. go read the reviews of Athlon64 CPUs with different cache sizes. its "old" but the principle stays the same.
Not so simple, for a "sane" L2 cache size (256KB-1MB range), latency does not need to rise "dramatically", there are other tunables like ways, power use, bandwidth, max clock that impact the speed of cache.
In fact with Skylake Intel went from 8 ways from 4 Ways for L2 cache, hurting cache perf, so increasing cache size can only help.

Intel said that Server core will be different from Desktop/Mobile, maybe they target 4Ghz multi core instead of 5ghz quad and can pump the savings into 1MB L2 as fast as their 256KB caches.

Large L2 does not need to be slow, just look at Apple A9 stuff, 3MB L2 with sub 10ns latency, but of course the clocks are sub 2Ghz :) Compare that to Skylake with ~12 cycle L2.
 
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Agent-47

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Jan 17, 2017
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Intel said that Server core will be different from Desktop/Mobile, maybe they target 4Ghz multi core instead of 5ghz quad and can pump the savings into 1MB L2 as fast as their 256KB caches.
yes i agree, that if you lower system wide clock, you can indeed have 1MB L2 cache as fast. it will save some power, i think as well. But will the increased cache size make up for the loss of raw clock, especially for application that donot overly depend on cache? I cannot say.

Interesting plot i found though:
 
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mikk

Platinum Member
May 15, 2012
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???
Lol. L2 may be faster, but the moment you increase the size of L2, its latency increases more drastically, so yes, gain will be marginal at best.

No, it's not that simple. You have no clue about the changes. Your link doesn't add anything and you are wrong, L2 isn't just a little bit faster. You didn't test Skylake-X, better shut up or make clear it's your own speculation but don't talk like it's a tested fact.
 

Sweepr

Diamond Member
May 12, 2006
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Interesting rumor about Skylake-X here. Apparently the 8C/16T SKU (or one of them) is able to beat 10C/20T Core i7-6950X. Better IPC thanks to Skylake core with new cache structure + higher clocks. :)



Intel is testing out Skylake-X, and beats out current 6950X with 8C because it can hit higher clocks.
http://www.overclock.net/t/1623292/lets-talk-about-a-ryzen-es

BenchLife already confirmed the existance of Skylake-X 10C SKU and apparently it's a 'K' model, not the 'X'. Expect some agressively clocked 6C/8C/10C models and perhaps something else (12C 'X'?). Launch in August.
 
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IntelUser2000

Elite Member
Oct 14, 2003
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Literally if they can double 6700K's cores, you'll get what they claim. Cinebench is also one of those benchmarks that don't care much about memory or cache. Not saying that's what he claimed though.

Also I have a hard time believing we'll get more than 5% gain in consumer setups. Remember, the changes only exist because its a derivative of server Skylake. Any bigger gains would entirely be targeted for server code and applications. And I'd think even 5% is stretching it. Unless you are talking only about games.
 

coercitiv

Diamond Member
Jan 24, 2014
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Interesting rumor about Skylake-X here. Apparently the 8C/16T SKU (or one of them) is able to beat 10C/20T Core i7-6950X. Better IPC thanks to Skylake core with new cache structure + higher clocks.
We need to remember that many-core server parts tend to benefit from process improvements just as much as mobile parts, and SKL + KBL brought quite a performance uplift over BDW in the mobile space. Looking at corresponding parts - BDW 5600U, SKL 6600U and KBL 7600U - turbo for MT loads went from 3.1 Ghz with BDW to 3.9 Ghz for KBL. That's a 25% frequency advantage from power savings alone (assuming they kept same power usage criteria for turbo). 10 core vs. 8 core is also a 25% advantage :)
 
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IntelUser2000

Elite Member
Oct 14, 2003
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That's a 25% frequency advantage from power savings alone (assuming they kept same power usage criteria for turbo). 10 core vs. 8 core is also a 25% advantage :)
Enthusiasts are the most finicky bunch. They want the highest clocks, they want the highest IPC with that, they want overclocking, they want affordable. On top of that it should run cool and use low power. Some of which run contrary to each other. In mobile, even with the same CPU often laptops perform way different. People are OK with that. In Desktops if the performance degrades 2% people cry foul.
 
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Chaptorial

Member
Feb 7, 2010
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I'm putting together a new Kaby Lake build and just wanted to give anyone in the same situation a heads up that Microcenter has a sale on Intel chips and components. I usually see the i7 7700k discounted there to $319 on a regular basis but with this current sale that appears to have started this morning, its on sale for $299. Ordered most of my components last night but was waiting to go and pickup the CPU at Microcenter. Definitely a great deal if you're near one of their stores.
 

nvgpu

Senior member
Sep 12, 2014
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With Coffee Lake going 6C/12T, hopefully Intel goes 8C/16T for i7 and 6C/12T for i5 with Icelake mainstream LGA 15xx platform.

HEDT LGA 2xxx platforms should really be 10C or more cores.
 

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