The Ice Lake Benchmark Preview: Inside Intel's 10nm
by Dr. Ian Cutress on August 1, 2019 9:00 AM EST- Posted in
- CPUs
- Intel
- GPUs
- 10nm
- Core
- Ice Lake
- Cannon Lake
- Sunny Cove
- 10th Gen Core
System Results (15W)
When testing a laptop system, there are various angles to consider on how to test: either user experience benchmarks, that are mostly single threaded and give a good boost to how systems implement a deal of turbo, or sustained benchmarks that test how the system performs when you push it. Intel has gone out of its way to emphasise the former for the next generation of mobile CPUs: they would prefer that reviewers stick to very user experience-like tests, rather than say, rendering programs. The problem there is that outside a number of canned benchmarks, it can be difficult. Users, and especially creators, that typically spend a lot on a premium device, might actually be doing sustained benchmarks.
Given the time that we had to test, we were actually limited in what we could arrange.
On AVX-512, the Ice Lake part destroys the competition.
These last two tests are typically our more memory sensitive tests, and the LPDDR4X-3733 really does win out over the LPDDR3-2133 in the other systems.
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jospoortvliet - Friday, August 2, 2019 - link
Sometimes people have insightful additions or questions. That is never you so I wouldn’t miss your ‘input’.Phynaz - Friday, August 2, 2019 - link
But yet you replied. Doh!Korguz - Friday, August 2, 2019 - link
and so did you !!! :-)Phynaz - Saturday, August 3, 2019 - link
Your comprehension skills aren’t that great, are they. Maybe that’s why you can’t afford a good cpu. Did you finish school?Korguz - Saturday, August 3, 2019 - link
yep.. but you obliviously havent as only children resort to insults, like you do. and again.. grow upPOlaris1983 - Thursday, August 1, 2019 - link
Thermals and TDP are a test for UNdervolting and OCing on THICC laptops using ai windows OS GUI interface apps for easy one button flipping on and off for these CPUs and GPUs and RAM Timings customizations. Even for desktop towers soon using keyboard functions in special keys like on a laptop once they solve the luqid cooling issues on the THICC laptops.thetrashcanisfull - Thursday, August 1, 2019 - link
Ian,In this and the Ryzen 3000 review, I noticed that the 3DPM benchmarks with AVX enabled seem to benefit from AVX-512 much more than I would anticipate.
If I'm understanding things correctly, the AVX-512 parts are capable of 2x512b FMAC / cycle in the case of Skylake-server or 1x512b FMAC + 1x512b ALU / cycle in the case of Sunny Cove, with both handling 2x512b load + 1x512b store / cycle. This would suggest to me that their vector FP performance/cycle ought to be around double that of Skylake-client or Zen 2, both of which do 2x256b FMAC / cycle and 2x256b loads + 1x256b store / cycle. However, in the 3DPM benchmark we see AVX-512 CPUs outpace the performance/cycle of AVX2 CPUs by a factor of 4 - possibly even more than 4, once we account for the frequency penalties associated with AVX-512!
Am I misunderstanding some critical piece of the AVX-512 extension that explains this boost, or is there something wrong with the AVX2 codepath for this benchmark? Only using xmm instructions? Not using FMA instructions?
Mysticial - Friday, August 2, 2019 - link
A while back, Ian sent me the non-vectorized and AVX512-vectorized binaries for 3DPM for me to analyze. (I never looked at the AVX2 version since this was before it was made.)Based on what I saw, I'm not at all surprised by the result. While I can't say that it fully explains such a large difference between AVX2 and AVX512, there are at least two things I noticed in the AVX512 binary that would contribute towards it.
1. There are 64-bit integer multiplies. AVX512 has the vpmullq instruction. AVX2 does not. Emulating this instruction in AVX2 is *extremely* costly.
2. The ratio of "heavy" to "light" AVX512 instructions is very low. Therefore, the 2nd FMA isn't needed to gain on AVX2.
I've never analyzed the AVX2 binary itself to see how that 64-bit multiply is being handled. It could be vectorized with extreme overhead, not vectorized at all, or worked-around at an algorithmic level.
thetrashcanisfull - Friday, August 2, 2019 - link
ohhhh... That makes more sense. I assumed that the 3DPM benchmark was doing primarily floating point math. I also didn't realize that AVX2 didn't support packed 64b muls... Thanks for the info!Alexvrb - Friday, August 2, 2019 - link
"The suggested PL2 for Kaby Lake-R was 44W, so this might indicate a small jump in strategy."Yeah, whereby TDP is virtually meaningless and every machine is a complete mystery box until you buy it and discover what actual thermals/power/performance are like - again regardless of the TDP. This is all without overclocking, mind you.