On 2020-05-13 9:46 a.m., Christian König wrote:
Am 12.05.20 um 23:12 schrieb Alex Deucher:
On Tue, May 12, 2020 at 4:52 PM Roy Spliet nouveau@spliet.org wrote:
I'll volunteer to be the one asking: how big is this performance difference? Have any benchmarks been run before and after removal of AGP GART code on affected nouveau/radeon systems? Or is this code being dropped _just_ because it's cumbersome, with no regard for metrics that determine the value of AGP GART support?
I don't think anyone has any solid numbers, just anecdotal from memory. I certainly don't have any functional AGP systems at this point. It's mostly just cumbersome and would allow us to clean ttm and probably improve stability at the same time. At least on the radeon side, the only native AGP cards were r1xx, r2xx, and some of the early r3xx boards. Once we switched to pcie mid-way through r3xx, everything was native pcie and the AGP cards used a pcie to AGP bridge chip so they had a decent on chip MMU. Those older cards topped out at maybe 32 or 64 MB of vram, so they are going to be hard pressed to deal with modern desktops anyway. No idea what sort of GART capabilities NV AGP hardware at this time had.
I could only test with an old x86 Mac and an r3xx generation hw and in this case making the switch didn't had any noticeable effect at all.
But I didn't do more than playing around with the desktop effects and playing a video.
Yeah, that's not enough to see a difference. Try an OpenGL game, or even just glxgears.