From: "Mariusz Janiak" <mariuszjaniak@wp.pl>
To: Zhoupeng <zhoupeng1982@qq.com>
Cc: xenomai <xenomai@xenomai.org>
Subject: Re: [Xenomai] Rtnet e1000e 82583: slow writel(tx_ring->tail), takes above 1us?
Date: Thu, 16 Apr 2015 14:26:19 +0200 [thread overview]
Message-ID: <552faa6bf2d134.92118662@wp.pl> (raw)
Dnia Czwartek, 16 Kwietnia 2015 13:30 Zhoupeng <zhoupeng1982@qq.com> napisał(a)
> I'm using Rtnet with 82583 ethernet card.
> It takes about 2us to send AF_PACKET using rt_dev_sendmsg(), about 200 bytes of data.
>
> It is pretty fast, but I want to find what takes so long.
> At last I find that "writel(tx_ring->tail)" spend above 1us to complete.
>
> This is just MMIO write to 82583, of course MMIO is uncache.
> And PCIE ASPM is disabled, so L0s is not the problem.
>
> I think PCIE Memory Write TLPs is fast enough, but why spend so much time?
Hi,
There is an interesting article that may be relevant to this issue
"PCI Express as a Killer of Software-based Real-Time Ethernet"
You can find copy in the attachment.
Best
Mariusz
> thanks,
> _______________________________________________
> Xenomai mailing list
> Xenomai@xenomai.org
> http://www.xenomai.org/mailman/listinfo/xenomai
-------------- next part --------------
A non-text attachment was scrubbed...
Name: rteth_hw_eval.pdf
Type: application/x-unknown
Size: 875870 bytes
Desc: not available
URL: <http://www.xenomai.org/pipermail/xenomai/attachments/20150416/f9dc8e97/attachment.bin>
next reply other threads:[~2015-04-16 12:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-16 12:26 Mariusz Janiak [this message]
2015-04-16 14:39 ` [Xenomai] Rtnet e1000e 82583: slow writel(tx_ring->tail), takes above 1us? Zhoupeng
2015-04-16 14:46 ` Gilles Chanteperdrix
2015-04-16 19:15 ` Gilles Chanteperdrix
-- strict thread matches above, loose matches on Subject: below --
2015-04-16 11:30 Zhoupeng
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=552faa6bf2d134.92118662@wp.pl \
--to=mariuszjaniak@wp.pl \
--cc=xenomai@xenomai.org \
--cc=zhoupeng1982@qq.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.