Messages in this thread Patch in this message | | | Date | Thu, 30 Aug 2001 13:49:30 -0700 | From | Jonathan Lahr <> | Subject | io_request_lock/queue_lock patch |
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Included below is a snapshot of a patch I am developing to reduce io_request_lock contention in 2.4.
This patch changes __make_request to take the device-specific queue_lock instead of io_request_lock and changes generic_unplug_device to take queue_lock in addition to io_request_lock to serialize access to the request queue. Also, locking in various functions has been modified in accordance with this new scheme.
I have done some testing of this with aic7xxx, qla2x00, and lpfc adapters.
To apply it to 2.4.6 or 2.4.7, from linux/ "patch -p1 < iorlv0_247".
Comments and suggestions are welcome and invited.
Jonathan
----- patch ----- diff -Naur linux.base/drivers/block/ll_rw_blk.c linux.mod/drivers/block/ll_rw_blk.c --- linux.base/drivers/block/ll_rw_blk.c Thu Jul 19 20:51:23 2001 +++ linux.mod/drivers/block/ll_rw_blk.c Fri Aug 24 10:17:38 2001 @@ -343,11 +343,13 @@ void generic_unplug_device(void *data) { request_queue_t *q = (request_queue_t *) data; - unsigned long flags; + unsigned long flags[2]; - spin_lock_irqsave(&io_request_lock, flags); + spin_lock_irqsave(&io_request_lock, flags[0]); + spin_lock_irqsave(&q->queue_lock, flags[1]); __generic_unplug_device(q); - spin_unlock_irqrestore(&io_request_lock, flags); + spin_unlock_irqrestore(&q->queue_lock, flags[1]); + spin_unlock_irqrestore(&io_request_lock, flags[0]); } static void blk_init_free_list(request_queue_t *q) @@ -470,9 +472,9 @@ add_wait_queue_exclusive(&q->wait_for_request, &wait); for (;;) { __set_current_state(TASK_UNINTERRUPTIBLE); - spin_lock_irq(&io_request_lock); + spin_lock_irq(&q->queue_lock); rq = get_request(q, rw); - spin_unlock_irq(&io_request_lock); + spin_unlock_irq(&q->queue_lock); if (rq) break; generic_unplug_device(q); @@ -487,9 +489,9 @@ { register struct request *rq; - spin_lock_irq(&io_request_lock); + spin_lock_irq(&q->queue_lock); rq = get_request(q, rw); - spin_unlock_irq(&io_request_lock); + spin_unlock_irq(&q->queue_lock); if (rq) return rq; return __get_request_wait(q, rw); @@ -555,7 +557,7 @@ drive_stat_acct(req->rq_dev, req->cmd, req->nr_sectors, 1); if (!q->plugged && q->head_active && insert_here == &q->queue_head) { - spin_unlock_irq(&io_request_lock); + spin_unlock_irq(&q->queue_lock); BUG(); } @@ -727,7 +729,7 @@ * Now we acquire the request spinlock, we have to be mega careful * not to schedule or do something nonatomic */ - spin_lock_irq(&io_request_lock); + spin_lock_irq(&q->queue_lock); insert_here = head->prev; if (list_empty(head)) { @@ -794,7 +796,7 @@ req = freereq; freereq = NULL; } else if ((req = get_request(q, rw)) == NULL) { - spin_unlock_irq(&io_request_lock); + spin_unlock_irq(&q->queue_lock); if (rw_ahead) goto end_io; @@ -821,7 +823,7 @@ out: if (freereq) blkdev_release_request(freereq); - spin_unlock_irq(&io_request_lock); + spin_unlock_irq(&q->queue_lock); return 0; end_io: bh->b_end_io(bh, test_bit(BH_Uptodate, &bh->b_state)); diff -Naur linux.base/drivers/scsi/scsi.c linux.mod/drivers/scsi/scsi.c --- linux.base/drivers/scsi/scsi.c Thu Jul 19 21:07:04 2001 +++ linux.mod/drivers/scsi/scsi.c Fri Aug 24 11:06:25 2001 @@ -678,41 +678,33 @@ * passes a meaningful return value. */ if (host->hostt->use_new_eh_code) { - spin_lock_irqsave(&io_request_lock, flags); rtn = host->hostt->queuecommand(SCpnt, scsi_done); - spin_unlock_irqrestore(&io_request_lock, flags); if (rtn != 0) { scsi_delete_timer(SCpnt); scsi_mlqueue_insert(SCpnt, SCSI_MLQUEUE_HOST_BUSY); SCSI_LOG_MLQUEUE(3, printk("queuecommand : request rejected\n")); } } else { - spin_lock_irqsave(&io_request_lock, flags); host->hostt->queuecommand(SCpnt, scsi_old_done); - spin_unlock_irqrestore(&io_request_lock, flags); } } else { int temp; SCSI_LOG_MLQUEUE(3, printk("command() : routine at %p\n", host->hostt->command)); - spin_lock_irqsave(&io_request_lock, flags); temp = host->hostt->command(SCpnt); SCpnt->result = temp; #ifdef DEBUG_DELAY - spin_unlock_irqrestore(&io_request_lock, flags); clock = jiffies + 4 * HZ; while (time_before(jiffies, clock)) barrier(); printk("done(host = %d, result = %04x) : routine at %p\n", host->host_no, temp, host->hostt->command); - spin_lock_irqsave(&io_request_lock, flags); #endif if (host->hostt->use_new_eh_code) { scsi_done(SCpnt); } else { scsi_old_done(SCpnt); } - spin_unlock_irqrestore(&io_request_lock, flags); } SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n")); return rtn; diff -Naur linux.base/drivers/scsi/scsi_lib.c linux.mod/drivers/scsi/scsi_lib.c --- linux.base/drivers/scsi/scsi_lib.c Thu Jul 19 20:48:04 2001 +++ linux.mod/drivers/scsi/scsi_lib.c Fri Aug 24 10:19:50 2001 @@ -68,7 +68,7 @@ static void __scsi_insert_special(request_queue_t *q, struct request *rq, void *data, int at_head) { - unsigned long flags; + unsigned long flags[2]; ASSERT_LOCK(&io_request_lock, 0); @@ -84,7 +84,8 @@ * head of the queue for things like a QUEUE_FULL message from a * device, or a host that is unable to accept a particular command. */ - spin_lock_irqsave(&io_request_lock, flags); + spin_lock_irqsave(&io_request_lock, flags[0]); + spin_lock_irqsave(&q->queue_lock, flags[1]); if (at_head) list_add(&rq->queue, &q->queue_head); @@ -92,7 +93,8 @@ list_add_tail(&rq->queue, &q->queue_head); q->request_fn(q); - spin_unlock_irqrestore(&io_request_lock, flags); + spin_unlock_irqrestore(&q->queue_lock, flags[1]); + spin_unlock_irqrestore(&io_request_lock, flags[0]); } @@ -246,13 +248,14 @@ void scsi_queue_next_request(request_queue_t * q, Scsi_Cmnd * SCpnt) { int all_clear; - unsigned long flags; + unsigned long flags[2]; Scsi_Device *SDpnt; struct Scsi_Host *SHpnt; ASSERT_LOCK(&io_request_lock, 0); - spin_lock_irqsave(&io_request_lock, flags); + spin_lock_irqsave(&io_request_lock, flags[0]); + spin_lock_irqsave(&q->queue_lock, flags[1]); if (SCpnt != NULL) { /* @@ -328,7 +331,8 @@ SHpnt->some_device_starved = 0; } } - spin_unlock_irqrestore(&io_request_lock, flags); + spin_unlock_irqrestore(&q->queue_lock, flags[1]); + spin_unlock_irqrestore(&io_request_lock, flags[0]); } /* @@ -821,6 +825,7 @@ struct Scsi_Device_Template *STpnt; ASSERT_LOCK(&io_request_lock, 1); + ASSERT_LOCK(&q->queue_lock, 1); SDpnt = (Scsi_Device *) q->queuedata; if (!SDpnt) { @@ -828,6 +833,7 @@ } SHpnt = SDpnt->host; + /* * To start with, we keep looping until the queue is empty, or until * the host is no longer able to accept any more requests. @@ -839,7 +845,7 @@ * we need to check to see if the queue is plugged or not. */ if (SHpnt->in_recovery || q->plugged) - return; + break; /* * If the device cannot accept another request, then quit. @@ -887,9 +893,11 @@ */ SDpnt->was_reset = 0; if (SDpnt->removable && !in_interrupt()) { + spin_unlock_irq(&q->queue_lock); spin_unlock_irq(&io_request_lock); scsi_ioctl(SDpnt, SCSI_IOCTL_DOORLOCK, 0); spin_lock_irq(&io_request_lock); + spin_lock_irq(&q->queue_lock); continue; } } @@ -998,8 +1006,6 @@ * another. */ req = NULL; - spin_unlock_irq(&io_request_lock); - if (SCpnt->request.cmd != SPECIAL) { /* * This will do a couple of things: @@ -1028,7 +1034,6 @@ { panic("Should not have leftover blocks\n"); } - spin_lock_irq(&io_request_lock); SHpnt->host_busy--; SDpnt->device_busy--; continue; @@ -1044,7 +1049,6 @@ { panic("Should not have leftover blocks\n"); } - spin_lock_irq(&io_request_lock); SHpnt->host_busy--; SDpnt->device_busy--; continue; @@ -1065,7 +1069,6 @@ * Now we need to grab the lock again. We are about to mess * with the request queue and try to find another command. */ - spin_lock_irq(&io_request_lock); } } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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