On Thu, Sep 30, 2021, at 10:24 AM, Sohil Mehta wrote: > On 9/30/2021 9:30 AM, Stefan Hajnoczi wrote: >> On Tue, Sep 28, 2021 at 09:31:34PM -0700, Andy Lutomirski wrote: >>> >>> I spent some time reviewing the docs (ISE) and contemplating how this all fits together, and I have a high level question: >>> >>> Can someone give an example of a realistic workload that would benefit from SENDUIPI and precisely how it would use SENDUIPI? Or an example of a realistic workload that would benefit from hypothetical device-initiated user interrupts and how it would use them? I'm having trouble imagining something that wouldn't work as well or better by simply polling, at least on DMA-coherent architectures like x86. >> I was wondering the same thing. One thing came to mind: >> >> An application that wants to be *interrupted* from what it's doing >> rather than waiting until the next polling point. For example, >> applications that are CPU-intensive and have green threads. I can't name >> a real application like this though :P. > > Thank you Stefan and Andy for giving this some thought. > > We are consolidating the information internally on where and how exactly > we expect to see benefits with real workloads for the various sources of > User Interrupts. It will take a few days to get back on this one. Thanks! > > >> (I can imagine some benefit to a hypothetical improved SENDUIPI with idential user semantics but that supported a proper interaction with the scheduler and blocking syscalls. But that's not what's documented in the ISE...) > > Andy, can you please provide some more context/details on this? Is this > regarding the blocking syscalls discussion (in patch 11) or something else? > Yes, and I'll follow up there. I hereby upgrade my opinion of SENDUIPI wakeups to "probably doable but maybe not in a nice way."
