On 3/13/23 11:50?AM, Pavel Begunkov wrote: > On 3/13/23 14:16, Jens Axboe wrote: >> On 3/12/23 9:45?PM, Pavel Begunkov wrote: >>>>>> Didn't take a closer look just yet, but I grok the concept. One >>>>>> immediate thing I'd want to change is the FACILE part of it. Let's call >>>>>> it something a bit more straightforward, perhaps LIGHT? Or LIGHTWEIGHT? >>>>> >>>>> I don't really care, will change, but let me also ask why? >>>>> They're more or less synonyms, though facile is much less >>>>> popular. Is that your reasoning? >>> >>>> Yep, it's not very common and the name should be self-explanatory >>>> immediately for most people. >>> >>> That's exactly the problem. Someone will think that it's >>> like normal tw but "better" and blindly apply it. Same happened >>> before with priority tw lists. >> >> But the way to fix that is not through obscure naming, it's through >> better and more frequent review. Naming is hard, but naming should be >> basically self-explanatory in terms of why it differs from not setting >> that flag. LIGHTWEIGHT and friends isn't great either, maybe it should >> just be explicit in that this task_work just posts a CQE and hence it's >> pointless to wake the task to run it unless it'll then meet the criteria >> of having that task exit its wait loop as it now has enough CQEs >> available. IO_UF_TWQ_CQE_POST or something like that. Then if it at some > > There are 2 expectations (will add a comment) > 1) it's posts no more that 1 CQE, 0 is fine > > 2) it's not urgent, including that it doesn't lock out scarce > [system wide] resources. DMA mappings come to mind as an example. > > IIRC is a problem even now with nvme passthrough and DEFER_TASKRUN DMA mappings aren't really scarce, only on weird/crappy setups with a very limited IOMMU space where and IOMMU is being used. So not a huge deal I think. >> point gets modified to also encompass different types of task_work that >> should not cause wakes, then it can change again. Just tossing >> suggestions out there... > > I honestly don't see how LIGHTWEIGHT is better. I think a proper > name would be _LAZY_WAKE or maybe _DEFERRED_WAKE. It doesn't tell > much about why you would want it, but at least sets expectations > what it does. Only needs a comment that multishot is not supported. Agree, and this is what I said too, LIGHTWEIGHT isn't a great word either. DEFERRED_WAKE seems like a good candidate, and it'd be great to also include a code comment there on what it does. That'll help future contributors. -- Jens Axboe
