On Tue, Jan 18, 2022 at 10:19:21AM -0800, Peter Oskolkov wrote: > =========== signals and the general approach > > My version of the patchset has all of these things working. What it > does not have, > compared to the new approach we are discussing here, is runqueues per server > and proper signal handling (and potential integration with proxy execution). > > Runqueues per server, in the LAZY mode, are easy to emulate in my patchset: > nothing prevents the userspace to partition workers among servers, and have > servers that "own" their workers to be pointed at by idle_server_tid_ptr. > > The only thing that is missing is proper treating of signals. But my patchset > does ensure a single running worker per server, had pagefaults and preemptions > sorted out, etc. Basically, everything works except signals. This patchet > has issues with pagefaults, Already fixed pagefaults per: YeGvovSckivQnKX8@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx > worker timeouts I still have no clear answer as to what you actually want there. > , worker-to-worker context > switches (do workers move runqueues when they context switch?), etc. Not in kernel, if they need to be migrated, userspace needs to do that. > And my patchset now actually looks smaller and simpler, on the kernel side, > that what this patchset is shaping up to be. > > What if I fix signals in my patchset? I think the way you deal with signals > will work in my approach equally well; I'll also use umcg_kick() to preempt > workers instead of sending them a signal. > > What do you think? I still absolutely hate how long you do page pinning, it *will* wreck things like CMA which are somewhat latency critical for silly things like Android camera apps and who knows what else. You've also forgotten about this: YcWutpu7BDeG+dQ2@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx That's not optional given how you're using page-pinning. Also, I think we need at least one direct access to the page after getting the pin in order to make it work. That also very much limits it to Anon pages.
