[PATCH 4.4 098/342] s390/dasd: fix performance drop
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-03-02 01:06:15
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4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Stefan Haberland <redacted>
commit 12d319b920fa673a4d5e7c1785c5dc82dcd15257 upstream.
Commit ca369d51b ("sd: Fix device-imposed transfer length limits")
introduced a new queue limit max_dev_sectors which limits the maximum
sectors for requests. The default value leads to small dasd requests
and therefor to a performance drop.
Set the max_dev_sectors value to the same value as the max_hw_sectors
to use the maximum available request size for DASD devices.
Signed-off-by: Stefan Haberland <redacted>
Signed-off-by: Martin Schwidefsky <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/s390/block/dasd.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c@@ -3031,6 +3031,7 @@ static void dasd_setup_queue(struct dasd max = block->base->discipline->max_blocks << block->s2b_shift; } queue_flag_set_unlocked(QUEUE_FLAG_NONROT, block->request_queue); + block->request_queue->limits.max_dev_sectors = max; blk_queue_logical_block_size(block->request_queue, block->bp_block); blk_queue_max_hw_sectors(block->request_queue, max);