lkml.org 
[lkml]   [2002]   [Oct]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Brust data send problem on gigabit NIC on Linux
Lk Overrun wrote:
> Hi, I am seeking advice on how to best send out huge
> number of packets on a gigabit ethernet interface. I
> am using kernel 2.4.19. I try to send out as many as
> possible 15Kbyte-long ethernet packets to try to
> utilize the giga-bit/sec bandwidth. My CPU is really
> fast (2 GHz) amd I dump the packets to the interface
> in a tight loop in user space. However, I can only
> reach around 400 Mbits/sec before the packets get
> dropped. The queue discipline (qdisc) seems to be
> responsible because the queue length (txqueuelen) is
> only 100 by default, and the queue just cannot store
> so many packets at once. I can eliminate the packet
> drop by raising the queue length to somewhere like
> 60000 but that is not practical because it uses too
> much memory. It seems I need some delay between
> sending packets but I cannot sleep for less than 10 ms
> (1/Hz) in user space and 10 ms is too long.
>
> I am using raw socket bypassing the IP stack and my
> NIC is the Intel Pro1000 (using the e1000.o driver).
>
> What is the best way to send raw ethernet packets,
> reaching gigabit range withuut packet drop on Linux?
> Thanks for any advice.

Make sure the e1000 driver is tuned, try insmodding it with:
TxDescriptors=1024 RxDescriptors=4096

Also, in your user-space app, check the return code of your
packet-sending call. That can let you know that the kernel
dropped it, and that you need to re-send.

How do you know you are dropping packets? (Ie, are you also
reading on another machine?) Usually it's read that drops
more packets than write.

Good luck,
Ben

>
>
>
> __________________________________________________
> Do you Yahoo!?
> Y! Web Hosting - Let the expert host your web site
> http://webhosting.yahoo.com/
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>


--
Ben Greear <greearb@candelatech.com> <Ben_Greear AT excite.com>
President of Candela Technologies Inc http://www.candelatech.com
ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:30    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site