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Commit 9cd13bdb authored by Bartlomiej Zolnierkiewicz's avatar Bartlomiej Zolnierkiewicz Committed by Jeff Garzik
Browse files

libata: add comment documenting PIO latency issues on UP 

Based on:
http://lkml.indiana.edu/hypermail/linux/kernel/0908.2/01420.html



Signed-off-by: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 5600c70e

drivers/ata/libata-core.c

+7 −0
Original line number Diff line number Diff line
@@ -6616,6 +6616,13 @@ static int __init ata_init(void) 
{

	ata_parse_force_param();



	/*

	 * FIXME: In UP case, there is only one workqueue thread and if you

	 * have more than one PIO device, latency is bloody awful, with

	 * occasional multi-second "hiccups" as one PIO device waits for

	 * another.  It's an ugly wart that users DO occasionally complain

	 * about; luckily most users have at most one PIO polled device.

	 */

	ata_wq = create_workqueue("ata");

	if (!ata_wq)

		goto free_force_tbl;