On Fri, Jan 20 2017, Paolo Valente wrote: > > > Il giorno 17 dic 2016, alle ore 01:12, Jens Axboe <axboe@xxxxxx> ha scritto: > > > > This is basically identical to deadline-iosched, except it registers > > as a MQ capable scheduler. This is still a single queue design. > > > > Jens, > no spin_lock_irq* in the code. So, also request dispatches are > guaranteed to never be executed in IRQ context? I'm asking this > question to understand whether I'm missing something that, even in > BFQ, would somehow allow me to not disable irqs in critical sections, > even if there is the slice_idle-expiration handler. Be patient with > my ignorance. Yes, dispatches will never happen from IRQ context. blk-mq was designed so we didn't have to use irq disabling locks. That said, certain parts of the API can be called from IRQ context. put_request and the completion parts, for instance. But blk-mq doesn't need to grab any locks there, and neither does mq-deadline. This might be different from bfq. lockdep can be a big help there. -- Jens Axboe -- 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
