From: Lee Revell <rlrevell@joe-job.com>
To: Open Source <opensource3141@yahoo.com>
Cc: linux-usb-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: USB performance bug since kernel 2.6.13 (CRITICAL???)
Date: Thu, 12 Oct 2006 16:19:12 -0400 [thread overview]
Message-ID: <1160684353.24931.79.camel@mindpipe> (raw)
In-Reply-To: <20061012200527.14579.qmail@web58107.mail.re3.yahoo.com>
On Thu, 2006-10-12 at 13:05 -0700, Open Source wrote:
> Hi,
>
> Thanks for the rapid response! But...I'm a bit confused. Why is there any software OS timer involved at all? Bulk messages should be scheduled by the host controller and for USB 2.0 the microframe period is 125 us. When I submit an URB, it should be sent to the host controller and scheduled for the next microframe. When the URB completes I should get an interrupt from the hardware. Hence, my transactions (WRITE followed by READ) should at worst be approximately 250 us plus some overhead to process the transaction itself, provided there aren't any other time consuming processes running on my OS. My overhead is less than 250 us. I was willing to tolerate 1 ms per transaction, but 4 ms just doesn't make any sense. Therefore I'm not sure if CONFIG_HZ is an appropriate excuse for this issue.
>
I don't know, it just seemed likely because 1ms vs 4ms is close to the
change in the timer tick rate. Try it.
Lee
next prev parent reply other threads:[~2006-10-12 20:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-12 20:05 USB performance bug since kernel 2.6.13 (CRITICAL???) Open Source
2006-10-12 20:19 ` Lee Revell [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-10-14 16:33 Open Source
2006-10-13 23:30 Open Source
2006-10-14 0:24 ` Alan Cox
2006-10-13 19:31 Open Source
2006-10-12 20:56 Open Source
2006-10-12 21:26 ` Lee Revell
2006-10-13 12:12 ` Ed Tomlinson
2006-10-12 19:33 Open Source
2006-10-12 19:55 ` Lee Revell
2006-10-12 19:21 Open Source
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=1160684353.24931.79.camel@mindpipe \
--to=rlrevell@joe-job.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb-devel@lists.sourceforge.net \
--cc=opensource3141@yahoo.com \
/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