4 ms·
More RAM could help us with a scale test, or maybe with a storage-related benchmark. Regarding the GIC, first I think we should spend some time examining the b
by _ananos_ 7y ago
More RAM could help us with a scale test, or maybe with a storage-related benchmark.
Regarding the GIC, first I think we should spend some time examining the benefits from the A72 upgrade. Then, breaking down the time spent on each step of the VM lifecycle should be fairly straightforward (annotate EL changes, capture numbers with perf or something similar).
- vardump 7y agoI have two 4 GB RPi4s, and can run any tests if you like. Or is this about some 1GB barrier DMA limitation? I did notice VideoCore can only access maximum 1GB of RAM. Related to that?
- _ananos_ 7y agothe issue about the available RAM is this: https://github.com/raspberrypi/linux/commit/cdb78ce891f6c6367a69c0a46b5779a58164bd4b#diff-634f284364ba43ef69912111615b08ef https://github.com/raspberrypi/linux/commit/cdb78ce891f6c636... probably some kind of address mapping, but I'm no expert on this stuff ;-)
- vardump 7y agoSaw that, but that doesn't really tell why, and how much effort is required to solve this. Maybe SD stuff is in the VideoCore side, and it simply can't DMA above 1 GB limit, and requires to have below 1GB DMA buffers + copy for transfers to upper memory. Maybe.