From: Paul Fulghum <paulkf@microgate.com>
To: Andrew Morton <akpm@digeo.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
johannes@erdfelt.com
Subject: Re: 2.5.69 Interrupt Latency
Date: 12 May 2003 09:06:09 -0500 [thread overview]
Message-ID: <1052748369.1996.15.camel@diemos> (raw)
In-Reply-To: <1052747862.1996.9.camel@diemos>
On Mon, 2003-05-12 at 08:57, Paul Fulghum wrote:
> On Fri, 2003-05-09 at 16:28, Andrew Morton wrote:
>
> > This code was added to wakeup_hc(). It is called from uhci_irq():
> >
> > + /* Global resume for 20ms */
> > + outw(USBCMD_FGR | USBCMD_EGSM, io_addr + USBCMD);
> > + wait_ms(20);
> >
> > The changelog just says "Minor patch for uhci-hcd.c"
> >
> > Can you delete the wait_ms() and see if that is our culprit?
>
> This is the culprit.
>
> Removing this line corrects the latency problems on
> the server. A 20ms delay seems pretty excessive for an
> interrupt handler. I'm not sure what it is supposed to
> accomplish, but this seems like something that should
> be scheduled to run outside of the ISR.
>
> I must have messed up a test on the laptop that is
> also showing latency problems. On the laptop the
> problem *is* in both 2.5.68/2.5.69 and *is not*
> eliminated by turning off USB. The laptop uses the
> ohci driver anyways which is not effected by this patch.
> The laptop does not show latency problems on 2.4.20.
>
> So the patch above is definately a problem,
> but the problem I am seeing on the laptop
> is something unrelated, but part of 2.5.x
> (which I will investigate further).
>
> Thanks,
> Paul
I forgot to add this snippet from the /var/log/messages file
of the server in case it helps the USB maintainer
in evaluating what to do about the above patch.
kernel: drivers/usb/host/uhci-hcd.c: USB Universal Host Controller Interface driver v2.0
kernel: uhci-hcd 00:04.2: Intel Corp. 82371AB/EB/MB PIIX4
kernel: uhci-hcd 00:04.2: irq 19, io base 0000fce0
kernel: Please use the 'usbfs' filetype instead, the 'usbdevfs' name is deprecated.
kernel: uhci-hcd 00:04.2: new USB bus registered, assigned bus number 1
kernel: hub 1-0:0: USB hub found
kernel: hub 1-0:0: 2 ports detected
--
Paul Fulghum, paulkf@microgate.com
Microgate Corporation, http://www.microgate.com
next prev parent reply other threads:[~2003-05-12 13:53 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-07 16:12 2.5.69 Interrupt Latency Paul Fulghum
2003-05-07 19:41 ` Paul Fulghum
2003-05-07 22:28 ` Andrew Morton
2003-05-08 0:25 ` Paul Fulghum
2003-05-08 13:56 ` Paul Fulghum
2003-05-08 19:22 ` Andrew Morton
2003-05-08 19:35 ` Paul Fulghum
2003-05-08 23:20 ` Brian Gerst
2003-05-09 18:12 ` Paul Fulghum
2003-05-09 20:30 ` Paul Fulghum
2003-05-09 21:28 ` Andrew Morton
2003-05-12 13:57 ` Paul Fulghum
2003-05-12 14:06 ` Paul Fulghum [this message]
2003-05-12 16:24 ` Greg KH
2003-05-12 17:08 ` Paul Fulghum
2003-05-12 17:30 ` Greg KH
2003-05-12 17:49 ` Paul Fulghum
2003-05-12 18:01 ` Greg KH
2003-05-12 18:15 ` Paul Fulghum
2003-05-13 15:26 ` Alan Stern
2003-05-13 15:35 ` Paul Fulghum
2003-05-13 17:30 ` Greg KH
2003-05-13 13:01 ` Paul Fulghum
2003-05-13 18:09 ` Greg KH
2003-05-13 18:11 ` Greg KH
2003-05-13 21:35 ` Alan Stern
2003-05-13 21:48 ` Helge Hafting
2003-05-13 22:09 ` Alan Stern
2003-05-14 21:06 ` Paul Fulghum
2003-05-14 21:15 ` Johannes Erdfelt
2003-05-14 21:30 ` Greg KH
2003-05-14 21:45 ` Paul Fulghum
2003-05-13 20:17 ` Bill Davidsen
2003-05-13 22:39 ` Paul Fulghum
2003-05-14 20:52 ` Test Patch: " Alan Stern
2003-05-15 13:45 ` Paul Fulghum
2003-05-15 14:12 ` Paul Fulghum
2003-05-15 21:07 ` Alan Stern
2003-05-15 15:26 ` Paul Fulghum
2003-05-15 18:11 ` Alan Stern
2003-05-15 18:40 ` Paul Fulghum
2003-05-15 19:42 ` Paul Fulghum
2003-05-15 19:59 ` Paul Fulghum
2003-05-15 21:13 ` Alan Stern
2003-05-15 21:30 ` Paul Fulghum
2003-05-15 19:17 ` Paul Fulghum
2003-05-16 15:33 ` Alan Stern
2003-05-16 15:58 ` Paul Fulghum
2003-05-16 16:18 ` Paul Fulghum
2003-05-16 17:16 ` Alan Stern
2003-05-16 17:48 ` Paul Fulghum
2003-05-16 18:31 ` Paul Fulghum
2003-05-16 18:40 ` Alan Stern
2003-05-16 19:05 ` Paul Fulghum
2003-05-18 0:57 ` Andrew McGregor
2003-05-16 17:20 ` Alan Stern
2003-05-16 17:51 ` Paul Fulghum
2003-05-19 16:41 ` Alan Stern
2003-05-19 18:20 ` Paul Fulghum
2003-05-19 18:49 ` Alan Stern
2003-05-16 18:10 ` Paul Fulghum
2003-05-14 17:50 ` Paul Fulghum
2003-05-09 21:07 ` Andrew Morton
2003-05-09 21:28 ` Paul Fulghum
2003-05-08 14:47 ` Paul Fulghum
[not found] <20030507162013$0b67@gated-at.bofh.it>
[not found] ` <20030507195008$71e6@gated-at.bofh.it>
[not found] ` <20030507224009$4228@gated-at.bofh.it>
[not found] ` <20030508140022$2498@gated-at.bofh.it>
[not found] ` <20030508193016$1083@gated-at.bofh.it>
[not found] ` <20030509182012$49f0@gated-at.bofh.it>
[not found] ` <20030509204010$3c9b@gated-at.bofh.it>
2003-05-09 21:06 ` Arnd Bergmann
2003-05-09 21:25 ` Paul Fulghum
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1052748369.1996.15.camel@diemos \
--to=paulkf@microgate.com \
--cc=akpm@digeo.com \
--cc=arnd@arndb.de \
--cc=johannes@erdfelt.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).