Comment on Me at CES today
Alk@sh.itjust.works 2 weeks ago9950x3d. It has double the cores of the 9800x3d, with an extra CCD that has 8 cores, but the 2nd CCD has no 3d cache. Which was known, to be fair, but still is disappointing.
Comment on Me at CES today
Alk@sh.itjust.works 2 weeks ago9950x3d. It has double the cores of the 9800x3d, with an extra CCD that has 8 cores, but the 2nd CCD has no 3d cache. Which was known, to be fair, but still is disappointing.
ggtdbz@lemmy.dbzer0.com 2 weeks ago
My understanding of the tech is that there are virtually no scenarios where having the 3D cache on the second CCD would actually help right now, unless I’ve got something wrong? Like even applications with enough threads to saturate the 3D CCD couldn’t possibly need that many threads that that
Unless you’re running multiple high-thread-count programs that benefit from the lower latency, and I don’t know what a realistic scenario for that would be. Some kind of multi-user scenario.
Granted I would have liked to see identical CCDs. I’m sure asymmetry is something they’ve figured out by now, but for the $$$ they’re asking for, a few extra overkill headroom can’t be a ridiculous ask.
empireOfLove2@lemmy.dbzer0.com 2 weeks ago
The single CCD cache stack was a huge problem with the original x3d dual ccd chips (7900/12coreand 7950/16core) as OS’es were not “ccd aware” about which chiplet has the cache. There is a huge access penalty for cache traversal between chiplets as the data has to travel across the infinity fabric rather than inside the CCD only. When the OS would distribute threads across both ccd’s because it only saw threads, you would never get the full benefit of x3d due to loads being placed on cores without x3d and incurring the traversal penalty. This has largely been fixed in Windows and Linux by now, but it still limits the true potential of the non-x3d ccd.
Dual cache stacks would allow both CCD’s to utilize the full benefits of a massive cache rather than just one.
Alk@sh.itjust.works 2 weeks ago
Exactly what I said in my comment at exactly the same time, but you worded it better 😅
Alk@sh.itjust.works 2 weeks ago
The main issue is having the 3d cache at all helps performance, and for gaming you’d want your game processes exclusively on the CCD with the 3d cache. So either you disable the other CCD (like windows’ game mode feature) or use software to force your game processes onto only the 3d CCD, which effectively turns the CPU into the 9800x3d anyway. Having processes for a single game split between both CCDs can cause jittering. From what I’ve heard, having a 3d cache on the 2nd CCD can eliminate that jittering, removing the need to manually keep game processes on the first CCD.