On Sat, Mar 30, 2024 at 12:13:35PM -0400, D. Hugh Redelmeier via talk wrote: > Fun fact: Mac folks never cease to brag about how great Unified Memory > is on the M1 etc. That seems silly when you realize that integrated > GPUs have always had this. But there is apparently a case where the > performance benefit is great:
Unified memory is a great idea when designed with the bandwidth it requires. The integrated video on PCs never was, it has no more bandwidth than the CPU without the integrated GPU had, so it was always costing you bandwidth your CPU needed. What the MAC has done, and what SGI did as well as some of the Xbox models, is design the system with lots of memory bandwidth, more than the CPU itself could ever take advantage of, which means anything you now put in ram is also useable directly by the GPU and neither is getting starved for bandwidth. So unified memory with high bandwidth is good. Unified memory with low bandwidth is bad. I remember a laptop my wife had with intel integrated video where doubling the ram made the machine way way faster because it allowed it to switch from single to dual channel access and doubled the bandwidth and suddenly the video wasn't starving the CPU as much anymore. It made way more difference than a bit more ram normally should have done. -- Len Sorensen --- Post to this mailing list talk@gtalug.org Unsubscribe from this mailing list https://gtalug.org/mailman/listinfo/talk
