Hacker News new | ask | show | jobs
by jkampman 419 days ago
This review is an object lesson about why there is so much more to shipping a decent processor than making a CPU core with reasonable performance (and decent is being polite given that we are talking about Bulldozer-class single-threaded perf, which most folks were beyond thrilled to abandon when Zen arrived eight years ago.)

The behavior of the memory controller is wild to see in this day and age. You really don't want to see latency that high in general, but especially not for a client processor. I'd really like to see how it behaves with a reasonably powerful GPU in a CPU-bound gaming workload relative to the competition (to simulate what one of these might see in an internet café setting, for instance).

Power efficiency also seems truly dismal according to PCWatch: https://pc.watch.impress.co.jp/docs/column/hothot/1626253.ht... . In Cinebench MT, it's consuming about the same power as a Ryzen 5 5600G while delivering about 1/3 the performance, and the idle power is much higher than the Core i3-8100/R5 5600G to boot. That's not a huge issue for desktops, but it would not make a good foundation for a mobile system.

Overall an improvement versus past Zhaoxin efforts but people shouldn't kid themselves about the quality of the overall package here. There is a long way to go.

3 comments

Absolutely a lomg way to go.

Interestingly, the chip is rated to run at DDR4-3200 or DDR5, so it's strange C&C got half that.

The power issues are likely from by modern standards pre-historical clocking behavior (single P-state to my understanding)!

It does clock ramp from 800 MHz idle to 3.2 GHz under load, with 900, 1000, 1100, 1300, 1500, 1800, 2200, and 2700 MHz steps in between until it hits 3.2 GHz after 71.6 ms. Article was getting long enough so I just left it at, it reaches 3.2 GHz and stays there even though the spec sheet says it should go higher.

I remoted into the system for testing (Cheese/George had it), and he said it took 3-4 cold reboots for it to come up, and suspected memory wasn't training correctly. So I did all the testing without ever rebooting the system, because it might not come back up if I tried.

Tangential but thank you for always providing such detailed benchmarks and insights. Your work is a treasure!
Memory controllers are the biggest bottleneck (ha) to performant systems these days. The cores themselves are fine, but the memory controllers are slow and buggy.
This appears to be a new x86 design, but why? I thought there was good riscv-64 stuff out there now.
(Binary) compatibility? Not everyone runs Linux, most software can't be recompiled. And emulation tends to come with a heavy speed penalty.
They are "cooperating" with VIA. Basically, they didn't start from 0.