Linked by Thom Holwerda on Fri 18th Aug 2017 10:51 UTC
AMD

In this mini-test, we compared AMD's Game Mode as originally envisioned by AMD. Game Mode sits as an extra option in the AMD Ryzen Master software, compared to Creator Mode which is enabled by default. Game Mode does two things: firstly, it adjusts the memory configuration. Rather than seeing the DRAM as one uniform block of memory with an ‘average’ latency, the system splits the memory into near memory closest to the active CPU, and far memory for DRAM connected via the other silicon die. The second thing that Game Mode does is disable the cores on one of the silicon dies, but retains the PCIe lanes, IO, and DRAM support. This disables cross-die thread migration, offers faster memory for applications that need it, and aims to lower the latency of the cores used for gaming by simplifying the layout. The downside of Game Mode is raw performance when peak CPU is needed: by disabling half the cores, any throughput limited task is going to be cut by losing half of the throughput resources. The argument here is that Game mode is designed for games, which rarely use above 8 cores, while optimizing the memory latency and PCIe connectivity.

I like how AnandTech calls this a "mini" test.

In any event - even though Threadripper is probably way out of the league of us regular people, I'm really loving how AMD's recent products have lit a fire under the processor market specifically and the self-built desktop market in general. Ever since Ryzen hit the market, now joined by Vega and Threadripper, we're back to comparing numbers and arguing over which numbers are better. We're back to the early 2000s, and it feels comforting and innocent - because everyone is right and everyone is wrong, all at the same time, because everything 100% depends on your personal budget and your personal use cases and no amount of benchmarks or number crunching is going to change your budget or personal use case.

I'm loving every second of this.

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RE[5]: Interesting
by cb88 on Fri 18th Aug 2017 21:38 UTC in reply to "RE[4]: Interesting"
cb88
Member since:
2009-04-23

I wouldn't be surprised if different microcode is loaded for the 2 modes... necessitating a reboot.

There is a lot of stuff most likely the CPU doesn't have to do when there is only 1 die. Also there are probably timing assumptions in the microcode that can be changed on this basis... could they potentially do that on the fly yes probably but that is harder.

Reply Parent Score: 2

RE[6]: Interesting
by Alfman on Fri 18th Aug 2017 22:22 in reply to "RE[5]: Interesting"
Alfman Member since:
2011-01-28

cb88,

I wouldn't be surprised if different microcode is loaded for the 2 modes... necessitating a reboot.

There is a lot of stuff most likely the CPU doesn't have to do when there is only 1 die. Also there are probably timing assumptions in the microcode that can be changed on this basis... could they potentially do that on the fly yes probably but that is harder.



Maybe, but if that's the case, then it really does set the platform back as a general purpose desktop. Nobody wants to reboot to switch to/from "gaming mode".

To make matters worse, end users will be confused about which mode to use for given software. "Gaming mode", despite the name, isn't just for games and "creator mode" isn't just for creation apps apps. It's a misnomer and will depend on the software.


This rebooting mess actually reminds me of the conditional sections in config.sys and autoexec.bat back in the days of DOS when we had to switch EMS/TSR settings depending on the software. This was a process of painstaking trial and error with many reboots to see which configurations worked with which programs.

Reply Parent Score: 2

RE[6]: Interesting
by tylerdurden on Sat 19th Aug 2017 01:32 in reply to "RE[5]: Interesting"
tylerdurden Member since:
2009-03-17

It's a windows issue, more than anything. I pretty much doubt MS included any core hot swapping/load migration code in the Pro and Home versions of Windows 10.

Reply Parent Score: 2

RE[7]: Interesting
by bert64 on Sat 19th Aug 2017 13:47 in reply to "RE[6]: Interesting"
bert64 Member since:
2007-04-23

It probably doesn't understand NUMA very well, if at all either... Otherwise the OS should take care of all these things, and ensure that processes are located in the correct memory zones for the CPU they're running on.

Linux basically owns the HPC market, which has had NUMA systems for years, so the support there is tried and tested and known to scale to very large NUMA systems. Windows only exists in the lowend where NUMA is far less common, and until now didn't exist at all in single socket desktops.

Reply Parent Score: 2