From 201bffa46466b4afdf7d29db8eca3fa5decb39c8 Mon Sep 17 00:00:00 2001 From: Bartlomiej Zolnierkiewicz Date: Fri, 2 Jan 2009 16:12:50 +0100 Subject: [PATCH] ide: use per-device request queue locks (v2) * Move hack for flush requests from choose_drive() to do_ide_request(). * Add ide_plug_device() helper and convert core IDE code from using per-hwgroup lock as a request lock to use the ->queue_lock instead. * Remove no longer needed: - choose_drive() function - WAKEUP() macro - 'sleeping' flag from ide_hwif_t - 'service_{start,time}' fields from ide_drive_t This patch results in much simpler and more maintainable code (besides being a scalability improvement). v2: * Fixes/improvements based on review from Elias: - take as many requests off the queue as possible - remove now redundant BUG_ON() Cc: Elias Oltmanns Signed-off-by: Bartlomiej Zolnierkiewicz --- drivers/ide/ide-io.c | 214 +++++++++++++--------------------------- drivers/ide/ide-park.c | 13 ++- drivers/ide/ide-probe.c | 3 +- include/linux/ide.h | 4 - 4 files changed, 77 insertions(+), 157 deletions(-) diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c index ab480042757a..bb3248abf47d 100644 --- a/drivers/ide/ide-io.c +++ b/drivers/ide/ide-io.c @@ -667,85 +667,10 @@ void ide_stall_queue (ide_drive_t *drive, unsigned long timeout) drive->sleep = timeout + jiffies; drive->dev_flags |= IDE_DFLAG_SLEEPING; } - EXPORT_SYMBOL(ide_stall_queue); -#define WAKEUP(drive) ((drive)->service_start + 2 * (drive)->service_time) - -/** - * choose_drive - select a drive to service - * @hwgroup: hardware group to select on - * - * choose_drive() selects the next drive which will be serviced. - * This is necessary because the IDE layer can't issue commands - * to both drives on the same cable, unlike SCSI. - */ - -static inline ide_drive_t *choose_drive (ide_hwgroup_t *hwgroup) -{ - ide_drive_t *drive, *best; - -repeat: - best = NULL; - drive = hwgroup->drive; - - /* - * drive is doing pre-flush, ordered write, post-flush sequence. even - * though that is 3 requests, it must be seen as a single transaction. - * we must not preempt this drive until that is complete - */ - if (blk_queue_flushing(drive->queue)) { - /* - * small race where queue could get replugged during - * the 3-request flush cycle, just yank the plug since - * we want it to finish asap - */ - blk_remove_plug(drive->queue); - return drive; - } - - do { - u8 dev_s = !!(drive->dev_flags & IDE_DFLAG_SLEEPING); - u8 best_s = (best && !!(best->dev_flags & IDE_DFLAG_SLEEPING)); - - if ((dev_s == 0 || time_after_eq(jiffies, drive->sleep)) && - !elv_queue_empty(drive->queue)) { - if (best == NULL || - (dev_s && (best_s == 0 || time_before(drive->sleep, best->sleep))) || - (best_s == 0 && time_before(WAKEUP(drive), WAKEUP(best)))) { - if (!blk_queue_plugged(drive->queue)) - best = drive; - } - } - } while ((drive = drive->next) != hwgroup->drive); - - if (best && (best->dev_flags & IDE_DFLAG_NICE1) && - (best->dev_flags & IDE_DFLAG_SLEEPING) == 0 && - best != hwgroup->drive && best->service_time > WAIT_MIN_SLEEP) { - long t = (signed long)(WAKEUP(best) - jiffies); - if (t >= WAIT_MIN_SLEEP) { - /* - * We *may* have some time to spare, but first let's see if - * someone can potentially benefit from our nice mood today.. - */ - drive = best->next; - do { - if ((drive->dev_flags & IDE_DFLAG_SLEEPING) == 0 - && time_before(jiffies - best->service_time, WAKEUP(drive)) - && time_before(WAKEUP(drive), jiffies + t)) - { - ide_stall_queue(best, min_t(long, t, 10 * WAIT_MIN_SLEEP)); - goto repeat; - } - } while ((drive = drive->next) != best); - } - } - return best; -} - /* * Issue a new request to a drive from hwgroup - * Caller must have already done spin_lock_irqsave(&hwgroup->lock, ..); * * A hwgroup is a serialized group of IDE interfaces. Usually there is * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640) @@ -757,8 +682,7 @@ repeat: * possibly along with many other devices. This is especially common in * PCI-based systems with off-board IDE controller cards. * - * The IDE driver uses a per-hwgroup spinlock to protect - * access to the request queues, and to protect the hwgroup->busy flag. + * The IDE driver uses a per-hwgroup lock to protect the hwgroup->busy flag. * * The first thread into the driver for a particular hwgroup sets the * hwgroup->busy flag to indicate that this hwgroup is now active, @@ -780,61 +704,38 @@ repeat: */ void do_ide_request(struct request_queue *q) { - ide_drive_t *orig_drive = q->queuedata; - ide_hwgroup_t *hwgroup = orig_drive->hwif->hwgroup; - ide_drive_t *drive; - ide_hwif_t *hwif; + ide_drive_t *drive = q->queuedata; + ide_hwif_t *hwif = drive->hwif; + ide_hwgroup_t *hwgroup = hwif->hwgroup; struct request *rq; ide_startstop_t startstop; - /* caller must own hwgroup->lock */ - BUG_ON(!irqs_disabled()); - - while (!ide_lock_hwgroup(hwgroup)) { - drive = choose_drive(hwgroup); - if (drive == NULL) { - int sleeping = 0; - unsigned long sleep = 0; /* shut up, gcc */ - hwgroup->rq = NULL; - drive = hwgroup->drive; - do { - if ((drive->dev_flags & IDE_DFLAG_SLEEPING) && - (sleeping == 0 || - time_before(drive->sleep, sleep))) { - sleeping = 1; - sleep = drive->sleep; - } - } while ((drive = drive->next) != hwgroup->drive); - if (sleeping) { + /* + * drive is doing pre-flush, ordered write, post-flush sequence. even + * though that is 3 requests, it must be seen as a single transaction. + * we must not preempt this drive until that is complete + */ + if (blk_queue_flushing(q)) /* - * Take a short snooze, and then wake up this hwgroup again. - * This gives other hwgroups on the same a chance to - * play fairly with us, just in case there are big differences - * in relative throughputs.. don't want to hog the cpu too much. + * small race where queue could get replugged during + * the 3-request flush cycle, just yank the plug since + * we want it to finish asap */ - if (time_before(sleep, jiffies + WAIT_MIN_SLEEP)) - sleep = jiffies + WAIT_MIN_SLEEP; -#if 1 - if (timer_pending(&hwgroup->timer)) - printk(KERN_CRIT "ide_set_handler: timer already active\n"); -#endif - /* so that ide_timer_expiry knows what to do */ - hwgroup->sleeping = 1; - hwgroup->req_gen_timer = hwgroup->req_gen; - mod_timer(&hwgroup->timer, sleep); - /* we purposely leave hwgroup locked - * while sleeping */ - } else - ide_unlock_hwgroup(hwgroup); + blk_remove_plug(q); - /* no more work for this hwgroup (for now) */ - goto plug_device; - } + spin_unlock_irq(q->queue_lock); + spin_lock_irq(&hwgroup->lock); - if (drive != orig_drive) - goto plug_device; + if (!ide_lock_hwgroup(hwgroup)) { +repeat: + hwgroup->rq = NULL; - hwif = drive->hwif; + if (drive->dev_flags & IDE_DFLAG_SLEEPING) { + if (time_before(drive->sleep, jiffies)) { + ide_unlock_hwgroup(hwgroup); + goto plug_device; + } + } if (hwif != hwgroup->hwif) { /* @@ -847,16 +748,20 @@ void do_ide_request(struct request_queue *q) hwgroup->hwif = hwif; hwgroup->drive = drive; drive->dev_flags &= ~(IDE_DFLAG_SLEEPING | IDE_DFLAG_PARKED); - drive->service_start = jiffies; + spin_unlock_irq(&hwgroup->lock); + spin_lock_irq(q->queue_lock); /* * we know that the queue isn't empty, but this can happen * if the q->prep_rq_fn() decides to kill a request */ rq = elv_next_request(drive->queue); + spin_unlock_irq(q->queue_lock); + spin_lock_irq(&hwgroup->lock); + if (!rq) { ide_unlock_hwgroup(hwgroup); - break; + goto out; } /* @@ -886,17 +791,21 @@ void do_ide_request(struct request_queue *q) startstop = start_request(drive, rq); spin_lock_irq(&hwgroup->lock); - if (startstop == ide_stopped) { - ide_unlock_hwgroup(hwgroup); - if (!elv_queue_empty(orig_drive->queue)) - blk_plug_device(orig_drive->queue); - } - } + if (startstop == ide_stopped) + goto repeat; + } else + goto plug_device; +out: + spin_unlock_irq(&hwgroup->lock); + spin_lock_irq(q->queue_lock); return; plug_device: - if (!elv_queue_empty(orig_drive->queue)) - blk_plug_device(orig_drive->queue); + spin_unlock_irq(&hwgroup->lock); + spin_lock_irq(q->queue_lock); + + if (!elv_queue_empty(q)) + blk_plug_device(q); } /* @@ -957,6 +866,17 @@ out: return ret; } +static void ide_plug_device(ide_drive_t *drive) +{ + struct request_queue *q = drive->queue; + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + if (!elv_queue_empty(q)) + blk_plug_device(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} + /** * ide_timer_expiry - handle lack of an IDE interrupt * @data: timer callback magic (hwgroup) @@ -974,10 +894,12 @@ out: void ide_timer_expiry (unsigned long data) { ide_hwgroup_t *hwgroup = (ide_hwgroup_t *) data; + ide_drive_t *uninitialized_var(drive); ide_handler_t *handler; ide_expiry_t *expiry; unsigned long flags; unsigned long wait = -1; + int plug_device = 0; spin_lock_irqsave(&hwgroup->lock, flags); @@ -989,12 +911,8 @@ void ide_timer_expiry (unsigned long data) * or we were "sleeping" to give other devices a chance. * Either way, we don't really want to complain about anything. */ - if (hwgroup->sleeping) { - hwgroup->sleeping = 0; - ide_unlock_hwgroup(hwgroup); - } } else { - ide_drive_t *drive = hwgroup->drive; + drive = hwgroup->drive; if (!drive) { printk(KERN_ERR "ide_timer_expiry: hwgroup->drive was NULL\n"); hwgroup->handler = NULL; @@ -1042,17 +960,18 @@ void ide_timer_expiry (unsigned long data) ide_error(drive, "irq timeout", hwif->tp_ops->read_status(hwif)); } - drive->service_time = jiffies - drive->service_start; spin_lock_irq(&hwgroup->lock); enable_irq(hwif->irq); if (startstop == ide_stopped) { ide_unlock_hwgroup(hwgroup); - if (!elv_queue_empty(drive->queue)) - blk_plug_device(drive->queue); + plug_device = 1; } } } spin_unlock_irqrestore(&hwgroup->lock, flags); + + if (plug_device) + ide_plug_device(drive); } /** @@ -1146,10 +1065,11 @@ irqreturn_t ide_intr (int irq, void *dev_id) unsigned long flags; ide_hwgroup_t *hwgroup = (ide_hwgroup_t *)dev_id; ide_hwif_t *hwif = hwgroup->hwif; - ide_drive_t *drive; + ide_drive_t *uninitialized_var(drive); ide_handler_t *handler; ide_startstop_t startstop; irqreturn_t irq_ret = IRQ_NONE; + int plug_device = 0; spin_lock_irqsave(&hwgroup->lock, flags); @@ -1236,12 +1156,10 @@ irqreturn_t ide_intr (int irq, void *dev_id) * same irq as is currently being serviced here, and Linux * won't allow another of the same (on any CPU) until we return. */ - drive->service_time = jiffies - drive->service_start; if (startstop == ide_stopped) { if (hwgroup->handler == NULL) { /* paranoia */ ide_unlock_hwgroup(hwgroup); - if (!elv_queue_empty(drive->queue)) - blk_plug_device(drive->queue); + plug_device = 1; } else printk(KERN_ERR "%s: %s: huh? expected NULL handler " "on exit\n", __func__, drive->name); @@ -1250,6 +1168,10 @@ out_handled: irq_ret = IRQ_HANDLED; out: spin_unlock_irqrestore(&hwgroup->lock, flags); + + if (plug_device) + ide_plug_device(drive); + return irq_ret; } diff --git a/drivers/ide/ide-park.c b/drivers/ide/ide-park.c index 44c6787f8aeb..678454ac2483 100644 --- a/drivers/ide/ide-park.c +++ b/drivers/ide/ide-park.c @@ -16,16 +16,19 @@ static void issue_park_cmd(ide_drive_t *drive, unsigned long timeout) spin_lock_irq(&hwgroup->lock); if (drive->dev_flags & IDE_DFLAG_PARKED) { int reset_timer = time_before(timeout, drive->sleep); + int start_queue = 0; drive->sleep = timeout; wake_up_all(&ide_park_wq); - if (reset_timer && hwgroup->sleeping && - del_timer(&hwgroup->timer)) { - hwgroup->sleeping = 0; - ide_unlock_hwgroup(hwgroup); + if (reset_timer && del_timer(&hwgroup->timer)) + start_queue = 1; + spin_unlock_irq(&hwgroup->lock); + + if (start_queue) { + spin_lock_irq(q->queue_lock); blk_start_queueing(q); + spin_unlock_irq(q->queue_lock); } - spin_unlock_irq(&hwgroup->lock); return; } spin_unlock_irq(&hwgroup->lock); diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c index f9efd069edc2..966b74c15773 100644 --- a/drivers/ide/ide-probe.c +++ b/drivers/ide/ide-probe.c @@ -881,8 +881,7 @@ static int ide_init_queue(ide_drive_t *drive) * do not. */ - q = blk_init_queue_node(do_ide_request, &hwif->hwgroup->lock, - hwif_to_node(hwif)); + q = blk_init_queue_node(do_ide_request, NULL, hwif_to_node(hwif)); if (!q) return 1; diff --git a/include/linux/ide.h b/include/linux/ide.h index f408d6123f14..5f86ad40ee7e 100644 --- a/include/linux/ide.h +++ b/include/linux/ide.h @@ -603,8 +603,6 @@ struct ide_drive_s { unsigned long dev_flags; unsigned long sleep; /* sleep until this time */ - unsigned long service_start; /* time we started last request */ - unsigned long service_time; /* service time of last request */ unsigned long timeout; /* max time to wait for irq */ special_t special; /* special action flags */ @@ -872,8 +870,6 @@ typedef struct hwgroup_s { /* BOOL: protects all fields below */ volatile int busy; - /* BOOL: wake us up on timer expiry */ - unsigned int sleeping : 1; /* BOOL: polling active & poll_timeout field valid */ unsigned int polling : 1; -- 2.20.1