The noop elevator is still too fat for db transaction processing workload.
Since the db application already merged all blocks before sending it down,
the I/O presented to the elevator are actually not merge-able anymore. Since
I/O are also random, we don't want to sort them either. However the noop
elevator is still doing a linear search on the entire list of requests in
the queue. A noop elevator after all isn't really noop.
We are proposing a true no-op elevator algorithm, no merge, no nothing. Just
do first in and first out list management for the I/O request. The best name
I can come up with is "FIFO". I also piggy backed the code onto noop-iosched.c.
I can easily pull those code into a separate file if people object. Though, I
hope Jens is OK with it.
--- linux-2.6.11/drivers/block/noop-iosched.c.orig 2005-03-28 16:37:30.000000000 -0800
+++ linux-2.6.11/drivers/block/noop-iosched.c 2005-03-28 16:43:57.000000000 -0800
@@ -74,6 +74,21 @@ static struct request *elevator_noop_nex
return NULL;
}
+static void elevator_fifo_add_request(request_queue_t *q, struct request *rq,
+ int where)
+{
+ list_add_tail(&rq->queuelist, &q->queue_head);
+}
+
+static struct elevator_type elevator_fifo = {
+ .ops = {
+ .elevator_next_req_fn = elevator_noop_next_request,
+ .elevator_add_req_fn = elevator_fifo_add_request,
+ },
+ .elevator_name = "fifo",
+ .elevator_owner = THIS_MODULE,
+};
+
static struct elevator_type elevator_noop = {
.ops = {
.elevator_merge_fn = elevator_noop_merge,
@@ -87,12 +102,14 @@ static struct elevator_type elevator_noo
static int __init noop_init(void)
{
- return elv_register(&elevator_noop);
+ return (elv_register(&elevator_noop) ||
+ elv_register(&elevator_fifo));
}
static void __exit noop_exit(void)
{
elv_unregister(&elevator_noop);
+ elv_unregister(&elevator_fifo);
}
module_init(noop_init);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
