* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > On Mon, Sep 28, 2015 at 10:47 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > >> It gets set by preemption - and, > >> somewhat illogically, by cond_resched(). > > > > I suspect that was done to make cond_resched() (voluntary preemption) > > more robust and only have a single preemption path/logic. But all that > > was done well before I got involved. > > So I think it's actually the name that is bad, not necessarily the behavior. > > We tend to put "cond_resched()" (and particularly > "cond_resched_lock()") in some fairly awkward places, and it's not > always entirely clear that task->state == TASK_RUNNING there. > > So the preemptive behavior of not *really* putting the task to sleep > may actually be the right one. But it is rather non-intuitive given > the name - because "cond_resched()" basically is not at all equivalent > to "if (need_resched()) schedule()", which you'd kind of expect. > > An explicit schedule will actually act on the task->state, and make us > go to sleep. "cond_resched()" really is just a "voluntary preemption > point". And I think it would be better if it got named that way. cond_preempt() perhaps? That would allude to preempt_schedule() and such, and would make it clearer that it's supposed to be an invariant on the sleep state (which schedule() is not). Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
