replace the default scheduler code with a udev rule

Quoted 4 lines

I leave it up to Stefan W. and Stefan H. to make comments to your suggestion. Thanks!

also, why deadline over cfq ?

_old_ IBM papers show a little gain of deadline in _some_ cases, but *today* ??

-thanks-

Quoted 48 lines

Full quote:

Quoted 46 lines

hi,

udev can handle it, as do 60-readahead.rules with read_ahead_kb in s390-tools.

change part of this, drivers/s390/block/dasd.c:

/*
* Allocate and initialize request queue and default I/O scheduler. */
static int dasd_alloc_queue(struct dasd_block *block)

{
	int rc;

	block->request_queue = blk_init_queue(do_dasd_request,
					&block->request_queue_lock);
	if (block->request_queue == NULL)
		return -ENOMEM;

	block->request_queue->queuedata = block;

	elevator_exit(block->request_queue->elevator);
	block->request_queue->elevator = NULL;
	rc = elevator_init(block->request_queue, "deadline");
	if (rc) {
		blk_cleanup_queue(block->request_queue);
		return rc;
	}
	return 0;
}

for this other, 61-scheduler.rules :

#
# Rules to change the default scheduler to deadline # This file should be installed in /etc/udev/rules.d #

SUBSYSTEM!="block", GOTO="ra_end"

ACTION!="add", GOTO="ra_end"

# on device add change the default scheduler to deadline
KERNEL=="sd*[!0-9]", ATTR{queue/scheduler}="deadline"
KERNEL=="dasd*[!0-9]", ATTR{queue/scheduler}="deadline"

Quoted 6 lines

Quoted 6 lines

LABEL="ra_end"

simpler, more flexible and less C code.

-thanks-