On Mon, May 19, 2014 at 11:18 PM, Christoph Hellwig <hch@xxxxxx> wrote: > On Mon, May 19, 2014 at 11:05:50PM +0800, Ming Lei wrote: >> Another simple fix is to disable ipi for flush request, but looks >> this one should be better. > > I think the first thing is to bite the bullet and sort out and document > the various unions in struct request for real. I agree, unions should be documented in detail. > > For example the first union has the call_single_data for the blk-mq blk-softirq need rq->csd too in raise_blk_irq(). > completions, while the second one has the ipi_list that is used by > the old blk-softirq code. Also we can put some mq specific fields and legacy fields into one union too. > > If we get this right with a single union that contains a struct for > each phase of the request we might find enough space to keep using > the current way. If we can figure it out, that should be better solution, but changing/ merging fields may affect performance too, and need careful verification. Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html