Jens Axboe <axboe@xxxxxxxxx> writes: >> I was curious about writes. ;-) Anyway, it's good to validate that the >> read case is also relevant. > > You mean O_DIRECT writes? Most of the buffered writes will come out of > the associated threads, so I don't think it's a big of an issue > there. We've only seen it for reads. Well, you had me confused with your initial report: "... because eg meta data updates..." So I assumed that meant REQ_META WRITES. My bad. [snip] >> Interesting. I would have thought that the cfqd->active_queue would >> have been preempted by a request marked with REQ_PRIO. But you're >> suggesting that did not happen? [snip] > We seem to handily mostly ignore prio_pending for the idle class. If Right, I forgot we were talking about idle class. Sorry. > the new queue is idle, then we don't look at prio pending. I'd rather > make this more explicit, the patch is pretty similar to what we had in > the past. It's somewhat of a regression caused by commit 4aede84b33d, > except I like using the request flags for this a lot more than the old > current->fs_excl. REQ_PRIO should always be set for cases where we > hold fs (or even directory) specific resources. Ah, thanks for the reference! Now I'll go back and finish reviewing the actual patch. -Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
