Hi, > Patch 8 replaces GEM VRAM with GEM SHMEM. The new memory manager > is more reliable and allows for larger resolutions. Valid point. > Display updates were so slow that Gnome was unmanageable with a > flickering cursor and single FPS. The new memory management makes > Gnome at least useable. Hmm? I'm wondering where this huge improvement comes from? With enough video memory VRAM performance should be ok. If video memory is tight and ttm is forced to shuffle around framebuffers between vram and system memory on each page flip (touching much of vram along the way which causes additional overhead on the qemu side), that is obviously very bad for performance. One of the reasons why cirrus uses SHMEM + shadowing since years. Shadow buffering comes with some overhead too, so the switch isn't an obvious win (assuming enough vram). Hiding the page flips from qemu might reduce the work qemu has to do though, especially if the shadowing uses dirty tracking and only touches the vram pages which have actually changed content. So there is a fair chance that this outweighs the shadowing overhead and ends up being a net win. I don't expect the difference being very big though. Also different display usage patterns might yield different results (fbcon vs. gnome for example). So this probably makes sense, but I'd like to see a bit more background information ... On vram sizes: The default qemu vram size (16M) should be fine for the default display resolution (1280x800). For FullHD vram size should be doubled (-device VGA,vgamem_mb=32). Skimmed the other patches, looks sane overall, but I don't follow drm close enough any more to do an full review. So I leave this here: Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx> take care, Gerd
