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s390/dasd: fix performance drop

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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 <sth@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stefan Haberland 2016-02-12 14:50:52 +01:00 • committed by Greg Kroah-Hartman
parent 2e80d52bc8
commit a90ad5c546
1 changed files with 1 additions and 0 deletions
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drivers/s390/block/dasd.c
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@ -3031,6 +3031,7 @@ static void dasd_setup_queue(struct dasd_block *block)
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);