On Thu, Sep 22, 2016 at 10:59:30PM +0200, Thomas Gleixner wrote: > On Thu, 22 Sep 2016, Mikulas Patocka wrote: > > On Mon, 19 Sep 2016, Peter Zijlstra wrote: > > > > > On Tue, Sep 13, 2016 at 09:39:59AM -0400, Mike Snitzer wrote: > > > > So I'm not sure how this dm-bufio local cond_resched() wrapper still got > > > > in... happy to take your patch. > > > > > > > > Please respond with whatever SOB you'd like applied to the patch header. > > > > > > Sorry, for the delay, here goes. > > > > Why not change it to might_sleep()? - that would be almost equivalent to > > You mean might_resched(). might_sleep() is not even remotely equivalent. It is, might_sleep() implies might_resched(). In fact, that's all what PREEMPT_VOLUNTARY is, make the might_sleep() debug test imply a resched point. > > If we call the cond_resched() function in tight loops such as walking all > > buffers in a list, there may be performance penalty due to the call, so > > the call should be done only if it is really needed (i.e. in > > CONFIG_PREEMPT_VOLUNTARY case). > > Makes sense. Is anybody still using PREEMPT_NONE? Most workloads also care about latency to some extend. Lots of code has explicit cond_resched() and doesn't worry. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
