Re: [gentoo-user] How to determine if a NIC is playing gigabit?

[YoYo siska]

On Mon, Jan 18, 2010 at 11:50:55AM +0000, Stroller wrote:
> Hi there,
>
> Yesterday I reseated the network cable between my server cupboard and my
> desk, and it now lights up on the switch by my desk as gigabit. But a
> file-transfer today is slower than I might have hoped.
>
> I'm not ruling out the cable, because it's pretty beat up (but the
> switch *is* lighting up as 1000), but how do I determine, please, that
> the Linux server at the other end is recognising the NIC and negotiating
> as gigabit speeds?

mii-tool (net-tools) or ethtool should be able to tell you that


> The hard-drives on the server are using an older PCI SATA card, and the
> NIC is also PCI. But I would have expected it to be a bit faster than
> 100Mbps.
>
> Any estimates over what kind of speed I should be seeing for large
> file-transfers over Samba? Wildly ball-park is fine - I wouldn't expect a
> 10x speed increase, but maybe 2x or 3x - 4x would be great!

don't know about samba, but with scp or nfs I can get about 20MByte/s which is
the speed of my disk (and for scp almost what my cpu can manage ;)
scp-ing /dev/zero gets me something short of 30MBye/s but that is
because my CPU cannot manage more ;)

You can see an estimate of your "raw" speed between the two machines by
running 
nc -l -p 7777 | pv >/dev/null
on one computer and 
pv /dev/zero | nc OTHER_COMPUTER 7777
on the other. I don't have a 1gbit  switch here right now, so can't give
you an estimate (with two notebooks connected directly by cable I just
got 100MByte/s, which is near enough to the theoretical maximum ;)
(pv is like cat, but displays a progressbar with act. speed, sys-apps/pv)

you can also try netperf for more precise benchmarks 

>
> I'll be testing between my Macs (both on the desktop switch, ruling out
> both the Linux box and the suspicious cable) later today, I'd just like
> some ideas of where I should be starting from.
>
> Right now I'm seeing 10 gigs of .mp4 files (1gb - 2gb per video file)
> taking about an hour - that's about what I'd expect from old 100Mbps
> networking, not this shiny new stuff.

hmm, that seems a bit low even for 100mbit, I have usually no problem getting
cca 10 MByte/s with 100mbit switches (without other traffic), though I
use either nfs or scp
the only time I remember using samba was with a winxp server, which
didn't go above 1MB/s, but I suspect that the problem was either on the
win side or some misunderstanding between win and linux ;)

>
> I'm not seeing any difference commenting & uncommenting "aio read size =
> 1, aio write size = 1" (separate lines) from /etc/samba/smb.conf and
> then running `/etc/init.d/samba reload`, but maybe I shouldn't expect
> that to make any difference on an existing transfer. I just don't want
> to interfere with this right now - I just want to copy as much as
> possible on to my laptop before I go out, and I'll take a look at this
> performance issue when I get home.
>
> Thanks in advance for any suggestions or pointers,
>
> Stroller.
>



yoyo