On Fri, Dec 22 2006, Christoph Hellwig wrote: > On Wed, Dec 20, 2006 at 12:50:02PM -0500, Kiyoshi Ueda wrote: > > Because I'd like to use blk_get_request() in q->request_fn() > > which can be called from interrupt context like below: > > scsi_io_completion -> scsi_end_request -> scsi_next_command > > -> scsi_run_queue -> blk_run_queue -> q->request_fn > > > Or request should not be allocated in q->request_fn() anyway? > > Do you have any other ideas? > > The right long-term fix is to make sure request_fn is only ever called > from process context. This means moving retry handling to a thread instead > of a softirq, but this will need careful performance testing and tweaking. It's a lot more than just retry handling. Most driver reinvoke queueing from the completion handling, so basically most of the time request_fn is run from either softirq (like SCSI) or interrupt context (like IDE). -- Jens Axboe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
