Intel’s Silvermont Architecture Revealed: Getting Serious About Mobile
by Anand Lal Shimpi on May 6, 2013 1:00 PM EST- Posted in
- CPUs
- Intel
- Silvermont
- SoCs
SoCs and Graphics
Intel isn’t talking about implementations of Silvermont today other than to say that it will show up in smartphones (Merrifield), tablets (Baytrail), automotive (unannounced), communications infrastructure products (Rangeley) and microservers (Avoton). Baytrail, the tablet implementation of Silvermont, will be available by the end of this year running both Windows 8 (8.1/Blue?) and Android. Silvermont based Merrifield phones will show up early in 2014.
What we know about Baytrail is that it will be a quad-core implementation of Silvermont paired with Intel’s own Gen 7 graphics. Although we don’t know clock speeds, we do know that Baytrail’s GPU core will feature 4 EUs - 1/4 the number used in Ivy Bridge’s Gen7 implementation (Intel HD 4000). Ultimately we can’t know how fast the GPU will be until we know clock speeds, but I wouldn’t be too surprised to see something at or around where the iPad 4’s GPU is today. Given Intel’s recent announcements around Iris and Iris Pro, it’s clear that the mobile team hasn’t yet had the graphics wakeup call that the Core team just got - but I suspect the Atom group will get there sooner rather than later. Intel’s eDRAM approach to scaling Haswell graphics (and CPU) performance has huge implications in mobile. I wouldn’t expect eDRAM enabled mobile SoCs based on Silvermont, but I wouldn’t be too surprised to see something at 14nm.
Penryn-Class Performance
When Atom first came out, I put its CPU performance in perspective by comparing it to older Pentium M based notebooks. It turned out that a 1.6GHz Atom performed similarly to a 1.2GHz Pentium M. So how does Silvermont stack up in PC notebook terms?
On single threaded performance, you should expect a 2.4GHz Silvermont to perform like a 1.2GHz Penryn. To put it in perspective of actual systems, we’re talking about around the level of performance of an 11-inch Core 2 Duo MacBook Air from 2010. Keep in mind, I’m talking about single threaded performance here. In heavily threaded applications, a quad-core Silvermont should be able to bat even further up the Penryn line. Intel is able to do all of this with only a 2-wide machine (lower IPC, but much higher frequency thanks to 22nm).
There’s no doubt in my mind that a Baytrail Android tablet will deliver amazing performance, the real unknown is whether or not a Baytrail Windows 8 detachable/convertible will be fast enough to deliver a good enough legacy Windows experience. I suspect it’ll take Airmont before we really get there by my standards, but it’ll be close this round for sure.
What’ll really be interesting to see is how Silvermont fares in smartphones. Max clock speeds should be lower than what’s possible in a tablet, but not by all that much thanks to good power management. When viewed in that light, I don’t know that there’s a more exciting mobile architecture announced at this point. The ability to deliver 2010 11-inch MacBook Air performance in a phone is insane.
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Homeles - Monday, May 6, 2013 - link
Yay confirmation bias!R0H1T - Tuesday, May 7, 2013 - link
Nay, you fanboi(Intel's) much ?powerarmour - Monday, May 6, 2013 - link
Have to agree, starting to get tired of these almost Intel PR based previews. No mention to how poor Intel's graphics drivers have consistently been over many many years.Homeles - Monday, May 6, 2013 - link
"You can't make the ridiculous claims of 1.6x performance."Sure you can. It was already a close race between a 5 year old architecture and a brand new one. The floodgates have opened -- this is 5 years of pent up performance gains from the largest R&D spender in the industry, on top of being on a significantly superior process for mobile devices.
Wilco1 - Monday, May 6, 2013 - link
Absolute performance of Silvermont cannot be higher than A15 or Bobcat, it's just 2-way OoO, has a single-issue in-order memory pipeline (no speculative execution of memory operations or dual issue of load-store like A15/Bobcat) and fairly small buffers in general. All in all it is more like A9 than A15 or Bobcat/Jaguar.althaz - Monday, May 6, 2013 - link
Except that it certainly can (dependent on a lot of other factors)...That said, I suspect it will only be faster at the same power level, not at the same frequency.
beginner99 - Tuesday, May 7, 2013 - link
That's covered in the article but I must admit I don't fully understand it. Anyway Anand writes about macro-op fusion and clearly states that because of this the 2-wide is misleading when directly comparing to ARM. My interpretation being that ARM doesn't have this and if your 2-wide CPU is running macro-ops with 2 instructions in them it's actually like 4-wide (but I guess this naive viewpoint of mine is completely wrong.Wilco1 - Tuesday, May 7, 2013 - link
No, macro-ops don't make your CPU magically wider. For example Silvermont cannot actually execute 2 load+op instructions every cycle, and cannot even execute 1 read-modify-write every cycle...Also note that most ARM CPUs do have similar capabilities, for example Cortex-A9 can execute 2 shifts and 2 ALU instructions every cycle, and loads and stores can have base update for free. So Anand is quite wrong claiming this is an advantage to Atom.
As I mentioned, the big bottleneck of Silvermont is it's single load/store unit. Typical code contains many loads and stores, and Cortex-A15 can execute these twice as fast as Silvermont.
Jaybus - Wednesday, May 8, 2013 - link
It can, however, execute 1 load and 1 store simultaneously, and that is its saving grace. That fits very well with code being executed in OoO fashion and why I doubt very much A15 is twice as fast executing typical code.Wilco1 - Thursday, May 9, 2013 - link
No Silvermont can only execute 1 load or 1 store per cycle. A15 won't be twice as fast on typical code, but it will beat Silvermont on memory intensive code due to its single memory pipeline bottleneck.