Palmer Dabbelt <palmer@xxxxxxxxxxx> writes: > On Tue, 30 Jan 2024 12:28:27 PST (-0800), stefanha@xxxxxxxxx wrote: >> On Tue, 30 Jan 2024 at 14:40, Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote: >>> >>> On Mon, 15 Jan 2024 08:32:59 PST (-0800), stefanha@xxxxxxxxx wrote: >>> > Dear QEMU and KVM communities, >>> > QEMU will apply for the Google Summer of Code and Outreachy internship >>> > programs again this year. Regular contributors can submit project >>> > ideas that they'd like to mentor by replying to this email before >>> > January 30th. >>> >>> It's the 30th, sorry if this is late but I just saw it today. +Alistair >>> and Daniel, as I didn't sync up with anyone about this so not sure if >>> someone else is looking already (we're not internally). <snip> >> Hi Palmer, >> Performance optimization can be challenging for newcomers. I wouldn't >> recommend it for a GSoC project unless you have time to seed the >> project idea with specific optimizations to implement based on your >> experience and profiling. That way the intern has a solid starting >> point where they can have a few successes before venturing out to do >> their own performance analysis. > > Ya, I agree. That's part of the reason why I wasn't sure if it's a > good idea. At least for this one I think there should be some easy to > understand performance issue, as the loops that go very slowly consist > of a small number of instructions and go a lot slower. > > I'm actually more worried about this running into a rabbit hole of > adding new TCG operations or even just having no well defined mappings > between RVV and AVX, those might make the project really hard. You shouldn't have a hard guest-target mapping. But are you already using the TCGVec types and they are not expanding to AVX when its available? Remember for anything float we will end up with softfloat anyway so we can't use SIMD on the backend. > >> Do you have the time to profile and add specifics to the project idea >> by Feb 21st? If that sounds good to you, I'll add it to the project >> ideas list and you can add more detailed tasks in the coming weeks. > > I can at least dig up some of the examples I ran into, there's been a > handful filtering in over the last year or so. > > This one > <https://gist.github.com/compnerd/daa7e68f7b4910cb6b27f856e6c2beba> > still has a much more than 10x slowdown (73ms -> 13s) with > vectorization, for example. > >> Thanks, >> Stefan -- Alex Bennée Virtualisation Tech Lead @ Linaro
