(no subject)

On Wed, 23 Oct 2002, bert hubert wrote:

On Wed, Oct 23, 2002 at 03:42:48PM +0200, Roy Sigurd Karlsbakk wrote:

quoted

quoted

The e1000 can very well do hardware checksumming on transmit.

The missing piece of the puzzle is that his application is not
using sendfile(), without which no transmit checksum offload
can take place.

As far as I've understood, sendfile() won't do much good with large files. Is 
this right?

I still refuse to believe that a 1.8GHz Pentium4 can only checksum
250megabits/second. MD Raid5 does better and they probably don't use a
checksum as braindead as that used by TCP.

If the checksumming is not the problem, the copying is, which would be a
weakness of your hardware. The function profiled does both the copying and
the checksumming.

But 250megabits/second also seems low.

Dave? 

Ordinary DUAL Pentium 400 MHz machine does this...


Calculating CPU speed...done
Testing checksum speed...done
Testing RAM copy...done
Testing I/O port speed...done

                     CPU Clock = 400  MHz
                checksum speed = 685  Mb/s
                      RAM copy = 1549 Mb/s
                I/O port speed = 654  kb/s


This is 685 megaBYTES per second.

                checksum speed = 685  Mb/s



Cheers,
Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
   Bush : The Fourth Reich of America