Intel's 128MB L4 Cache May Be Coming to Desktops with 14nm Broadwell-K CPUs

rated by 0 users
This post has 7 Replies | 0 Followers

Top 10 Contributor
Posts 26,505
Points 1,197,020
Joined: Sep 2007
ForumsAdministrator
News Posted: Thu, Nov 21 2013 3:40 PM
When Intel debuted Haswell this year, it launched its first mobile processor with a massive 128MB L4 cache. Dubbed "Crystal Well," this on-package (not on-die) pool of memory wasn't just a graphics frame buffer, but a giant pool of RAM for the entire core to utilize. The performance impact from doing so is significant, though the Haswell processors that utilize the L4 cache don't appear to account for very much of Intel's total CPU volume.

Right now, the L4 cache pool is only available on mobile parts, but that could change next year. According to CPU-World, Broadwell-K will change that. The 14nm desktop chips aren't due until the tail end of next year -- we should see a desktop refresh in the spring with a second-generation Haswell part. Still, it's a sign that Intel intends to integrate the large L4 as standard on a wide range of parts.

Why Crystal Well Matters



There are two reasons to pay attention to Crystal Well. First, it's entirely possible that Intel will integrate the massive cache across all chips at some future date. Using EDRAM instead of SRAM allows the company to dedicate just one transistor per cell instead of the 6T configurations commonly used for L1 or L2 cache. That means the memory isn't quite as fast or as efficient as it might be, but it saves an enormous amount of die space. At 1.6GHz, L4 latencies are 50-60ns -- significantly higher than the L3, in other words, but just half the speed of main memory.

By integrating that huge pool of memory into desktop processors, Intel stands to boost performance modestly in both graphics and non-graphics workloads. And that's important, given the company's focus on form factors like NUC, which have no space for an external graphics card built to desktop specifications. The goal, for Intel, is to simultaneously build chips that hit "good enough" graphics and to expand the definition of "good enough" to include an increasingly large number of people.

That's a hump that AMD has struggled with for years. The fact is, casual users don't care much about integrated graphics, provided they can watch video and perform other basic tasks. In order to serve as a major selling point, AMD either needs HSA functionality (to offer acceleration in regular workloads), dramatically faster graphics for casual tasks like web surfing, or high enough integrated performance to attract low-end gamers. Strong video and fast accelerated web browsing are features Intel offers already, so AMD"s ability to hack out a clear win on these points is limited. Faster gaming performance is something the company is definitely shooting for with Mantle and its upcoming Kaveri APU, as well as broad support for HSA.

If Intel moves to make Crystal Well a standard option on desktop parts for 14nm (including the second-generation 14nm chip, Sky Lake), it's also a step towards integrating the L4 buffer into a wider variety of mobile chips. This generation, on 22nm, only 45W chips have the integrated buffer. It's entirely possible that we'll see 14nm mobile parts w/ the large L4 pushing into 25-35W TDPs. That's going to put still more pressure on AMD's mobile Kaveri.

The desktop threat, meanwhile, could be even larger. If Intel pushes the next-generation implementation of its graphics architecture to take advantage of a 75-88W TDP, it might be able to challenge Nvidia and AMD discrete cards at the low end,
  • | Post Points: 110
Not Ranked
Posts 1
Points 5
Joined: Nov 2013

Yo me acuerdo del Celeron Mendocino que tenía 128KB de L2

  • | Post Points: 5
Not Ranked
Posts 3
Points 15
Joined: Nov 2013

Nice

  • | Post Points: 5
Top 500 Contributor
Posts 276
Points 3,040
Joined: Sep 2009
Location: Port Orchard, WA

Very Interesting about add L4 caches on Intel CPU. Well we will find out in future. I hope Intel will put L4 caches add on next gen Extreme Edition on Desktop. Who know?

  • | Post Points: 5
Top 100 Contributor
Posts 1,077
Points 11,665
Joined: Jul 2009
Joel H replied on Thu, Nov 21 2013 7:23 PM

Mike,

I would be surprised if that shows up for Haswell-E. Remember, Broadwell is the 14nm version, but Haswell-E, which ships next year, is still 22nm. Those chips also have 8 cores already, so integrating a huge EDRAM would be more expensive (relative to die size).

I might expect Intel to integrate the cache into the generation of EE chips after this one.

MichaelJ,

The rule of thumb is that we gain about one cache level per decade. It's not far off. ;)

  • | Post Points: 5
Not Ranked
Posts 41
Points 355
Joined: Sep 2012

MEGAbytes?

  • | Post Points: 5
Not Ranked
Posts 1
Points 5
Joined: Nov 2013
MikeMallen replied on Fri, Nov 22 2013 10:00 PM

CAMPUTER is coming! So long Hard-Drive and SSD!

  • | Post Points: 5
Top 100 Contributor
Posts 1,077
Points 11,665
Joined: Jul 2009
Joel H replied on Fri, Nov 22 2013 11:00 PM

Uh. Don't think we're anywhere near that point yet. Though it'd be hilarious to put DOS + games on the L4 cache of a chip. ;)

  • | Post Points: 5
Page 1 of 1 (8 items) | RSS