Hi, thanks for the comments, On Fri, 2 May 2008 16:04:54 +0200 Borislav Petkov <petkovbb@xxxxxxxxxxxxxx> wrote: > Hi, > > On Thu, May 01, 2008 at 09:27:57PM +0900, FUJITA Tomonori wrote: > > This is an updated version of the patchset to clean up the asymmetry > > of blk_get/put_request usage: > > > > http://marc.info/?l=linux-ide&m=120882410712466&w=2 > > > > This patchset removes the code calling blk_put_request against the > > requests that are not allocated via blk_get_request. They can use > > __GFP_WAIT allocation so we can easily convert them to > > use blk_get/put_request properly. > > > > This patchset enables us to remove the following hack in > > blk_put_request: > > > > /* > > * Gee, IDE calls in w/ NULL q. Fix IDE and remove the > > * following if (q) test. > > */ > > if (q) { > > spin_lock_irqsave(q->queue_lock, flags); > > __blk_put_request(q, req); > > spin_unlock_irqrestore(q->queue_lock, flags); > > } > > > > The major changes are: > > > > - I remove the ide_wait/head_wait path in ide_do_drive_cmd(). It does > > the same thing that blk_execute_rq() does. > > Are you sure about that? Not that I'm that familiar with the blk layer internals > but at a glance blk_execute_rq() calls blk_execute_rq_nowait() and in it, the > rq is added to the elevator and the device queue is being plugged (4th arg > to __elv_add_request(...,1)) and after the last returns the device is being > unplugged again: __generic_unplug_device(q). This way no rq's are getting merged > and it might hurt performance, IMHO. Yes, no requests are merged, but 1. the ide_wait/head_wait path in ide_do_drive_cmd() doesn't handle any mergeable requests. All the requests are for kinda management. We like to execute such as soon as possible. 2. I don't think that ide_do_drive_cmd merges requests. In case of ELEVATOR_INSERT_FRONT, it calls ide_do_request right after elv_insert. ide_do_request takes a request from the queue and executes it? In case of ELEVATOR_INSERT_BACK, elv_insert calls q->request_fn, that is, ide_do_request is called. -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
