From owner-freebsd-mobile Sat Oct 19 12: 8: 8 2002 Delivered-To: freebsd-mobile@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5A82637B401 for ; Sat, 19 Oct 2002 12:08:07 -0700 (PDT) Received: from fiinbeck.math.ntnu.no (fiinbeck.math.ntnu.no [129.241.15.140]) by mx1.FreeBSD.org (Postfix) with SMTP id 24FE843E8A for ; Sat, 19 Oct 2002 12:08:06 -0700 (PDT) (envelope-from hanche@math.ntnu.no) Received: (qmail 517 invoked from network); 19 Oct 2002 19:08:04 -0000 Received: from localhost (127.0.0.1) by localhost with SMTP; 19 Oct 2002 19:08:04 -0000 To: freebsd-mobile@FreeBSD.ORG Subject: 100 Mbit/s is (a lot) slower than 10 Mbit/s X-Mailer: Mew version 1.94.2 on Emacs 21.2 / Mule 5.0 (SAKAKI) X-URL: http://www.math.ntnu.no/~hanche/ Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 8bit Message-Id: <20021019210804P.hanche@math.ntnu.no> Date: Sat, 19 Oct 2002 21:08:04 +0200 From: Harald Hanche-Olsen X-Dispatcher: imput version 20000228(IM140) Lines: 37 Sender: owner-freebsd-mobile@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org I have a Linksys ethernet card in my laptop. It can to 10 or 100 Mbit/s. But when it's in 100 Mbit/s mode, transfers into the laptop are lots slower than at 10 Mbit/s, at least as long as the sender is on the same local net and has a 100 Mbit/s interface. The reason is obvious enough: Snooping on the ethernet traffic reveals that packets are lost, with frequent timeouts and waits for retransmissions as a result. The timeouts are easily visible by watching the blinkenlights on the dongle. I am assuming this is a result of the Linksys' puny buffer being overrun, perhaps due to the bandwidth from the PCMCIA slot to the CPU not being big enough to cope. So why don't I just use 10 Mbit/s then? Well, at home that is what I do, since I can tell my stationary PC to run its interface at 10 Mbit/s, and the Linksys will automatically follow suit. But at work we recently upgraded our network to 100 Mbit/s, and hence the difficulty: The ed driver has no provision (it seems) for setting the speed. (Maybe there is no way to ask the card to pick the lower speed.) Could anyone suggest a reasonable workaround? I though maybe I could set some kernel variables to make the window size in TCP smaller and hence stop the buffer overrun from happening so often, but I am not sure what knob to twiddle or even if there is one. (Yes, recompiling the kernel is okay, too.) Is this a common problem? I don't see a lot of complaints about it on the list. Maybe it's just the card that's crappy, and I should get another one? FWIW, the card calls itself an EtherFast (ha!) 10/100 PC Card. I got it back in 1999 because it was cheap, so I have got enough use out of it and won't be unduly upset if I need to scrap it. - Harald PS. If the ethernet cable or dongle is disconnected for any reason, the laptop hangs until I lean on the power button. Very annoying. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message