On Wed, Nov 24, 2021 at 6:06 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Mon, Nov 22, 2021 at 01:13:21PM -0800, Peter Oskolkov wrote: > > User Managed Concurrency Groups (UMCG) is an M:N threading > > subsystem/toolkit that lets user space application developers implement > > in-process user space schedulers. > > > > This v0.9.1 patchset is the same as v0.9, where u32/u64 in > > uapi/linux/umcg.h are replaced with __u32/__u64, as test robot/lkp > > does not recognize u32/u64 for some reason. > > > > v0.9 is v0.8 rebased on top of the current tip/sched/core, > > with a fix in umcg_update_state of an issue reported by Tao Zhou. > > > > Key changes from patchset v0.7: > > https://lore.kernel.org/all/20211012232522.714898-1-posk@xxxxxxxxxx/: > > > > - added libumcg tools/lib/umcg; > > - worker "wakeup" is reworked so that it is now purely a userspace op, > > instead of waking the thread in order for it to block on return > > to the userspace immediately; > > - a couple of minor fixes and refactorings. > > > > These big things remain to be addressed (in no particular order): > > - support tracing/debugging > > - make context switches faster (see umcg_do_context_switch in umcg.c) > > - support other architectures > > - cleanup and post selftests in tools/testing/selftests/umcg/ > > - allow cross-mm wakeups (securely) > > *groan*... so these patches do *NOT* support the very thing this all > started with, namely block + wakeup notifications. I'm really not sure > how that happened, as that was the sole purpose of the exercise. I'm not sure why you say this - in-process block/wakeup is very much supported - please see the third patch. Cross-process (cross-mm) wakeups are not supported at the moment, as the security story has to be fleshed out. > > Aside of that, the whole uaccess stuff is horrific :-( I'll reply to > that email separately, but the alternative is also included in the > random hackery below. Thanks - I'll try to make uaccess more to your liking, unless you say the whole thing is a no-go. > > I'm still trying to make sense of it all, but I'm really not seeing how > any of this satisfies the initial goals, also it is once again 100% new > code :/ I believe the initial goals of in-process block/wakeup detection, on-cpu context switching, etc. are all achieved here. Re: new code: the code in the third patch evolved into what it is today based on feedback/discussions in this list. [...]
