Commit 68d95b58 authored Mar 04, 2008 by Mike Miller Committed by Jens Axboe Mar 04, 2008

cciss: remove READ_AHEAD define and use block layer defaults

This patch removes the #define READ_AHEAD 1024 from the driver and uses the
block layer defaults, instead. We have found that under certain workloads
the setting can cause a disk connected to the e200 controller to go offline.
If the disk hiccups the link may try to downshift but the controller is
never notified that the link successfully completed the renegotiation.
We've also found that performance using the block layer default of 32 pages
was on par with the 1024 setting. We tried setting it to zero at one time
based on info from our firmware guys but that killed performance. Turns out
we were talking about 2 different read ahead settings.
Please consider this for inclusion.

Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

parent ecb80c6a

drivers/block/cciss.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -132,7 +132,6 @@ static struct board_type products[] = {
		/define how many times we will try a command because of bus resets /
		#define MAX_CMD_RETRIES 3

		#define READ_AHEAD 1024
		#define MAX_CTLR 32

		/* Originally cciss driver only supports 8 major numbers */
		@@ -1402,7 +1401,6 @@ geo_inq:
		disk->private_data = &h->drv[drv_index];

		/* Set up queue information */
		disk->queue->backing_dev_info.ra_pages = READ_AHEAD;
		blk_queue_bounce_limit(disk->queue, hba[ctlr]->pdev->dma_mask);

		/* This is a hardware imposed limit. */
		@@ -3495,7 +3493,6 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
		}
		drv->queue = q;

		q->backing_dev_info.ra_pages = READ_AHEAD;
		blk_queue_bounce_limit(q, hba[i]->pdev->dma_mask);

		/* This is a hardware imposed limit. */

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