* [PATCH] libata: add comment documenting PIO latency issues on UP
@ 2009-11-26 16:11 Bartlomiej Zolnierkiewicz
2009-12-03 7:36 ` Jeff Garzik
0 siblings, 1 reply; 2+ messages in thread
From: Bartlomiej Zolnierkiewicz @ 2009-11-26 16:11 UTC (permalink / raw)
To: Jeff Garzik; +Cc: linux-ide, linux-kernel
Based on:
http://lkml.indiana.edu/hypermail/linux/kernel/0908.2/01420.html
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
drivers/ata/libata-core.c | 7 +++++++
1 file changed, 7 insertions(+)
Index: b/drivers/ata/libata-core.c
===================================================================
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6624,6 +6624,13 @@ 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;
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2009-12-03 7:50 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-11-26 16:11 [PATCH] libata: add comment documenting PIO latency issues on UP Bartlomiej Zolnierkiewicz
2009-12-03 7:36 ` Jeff Garzik
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).