Messages in this thread |  | | Date | Wed, 27 Sep 2000 15:42:12 +0200 | From | Arnaud Installe <> | Subject | Re: 3c59x problems solved -- mostly |
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On Wed, Sep 27, 2000 at 11:26:09PM +1100, Andrew Morton wrote: > > Any suggestions to reduce those even further > > more than welcome, as I suppose this might cause some Multicast UDP > > packets to get dropped. :-/ > > Yes, you'll be dropping packets.
Hmm... Not good.
> > Would using SCSI instead of IDE help, do you think ? > > It depends upon the SCSI driver. I haven't measured kernel interrupt > latencies for a while. Back in March, IDE beat the pants off SCSI in > this regard. > > The IDE system was UDMA-66 (using hdparm -u1 -d1). The SCSI sytem was > from Advansys (I don't know how good this driver is). The numbers are > at http://www.uow.edu.au/~andrewm/linux/intlat/intlat-disk.html. This > was for the 2.3.99 kernel. > > IDE: 27 usecs > SCSI: 42 usecs > > Still, these aren't large enough to explain this behaviour.
What we're seeing is we stress the hd's so much the whole system becomes terribly slow whenever a disk access is needed. Simply logging in on the console takes ages then. Perhaps this could explain those buffer overruns ?
> Are you sending much output to the console? You'll see from Doug > Gilbert's numbers that the console driver can block interrupts for a > millisecond. Try running X, or otherwise prevent things from writing to > the console.
Nope. Just X clients running on a remote X server.
> The sensible alternative, of course, is to use a multicast filter. The > 3c905B/C does have a 256 slot hash filter. Unfortunately (and > uncharacteristically), 3com forgot to document it. However it _is_ > implemented in 3com's own GPL'ed driver. This driver is bundled in > RedHat 6.x and is available at > http://support.3com.com/infodeli/tools/nic/linux.htm . It's worth > visiting that site just for the amusement factor of having to click on > "I agree" for the license. It's the GPL!
Thanks for the info. So the standard driver uses a software filter for multicasts then ? What does that mean ? Not promiscuous mode, I suppose ?
> > The 2.2.17 driver still seems to have a few bugs though: we get messages > > like: "Too much work in interrupt, status e401". This seems to happen > > more on machines with RX buffer overruns. > > hmm.. Yes, something is wrong. I see this could perhaps silently > happen if the driver is hopelessly out of memory. And this would > explain the failure you saw in the 2.2.16 driver. It had an > Rx-stops-working-on-OOM bug. > > Could you please, before doing anything else, see if > > echo '512 1024 1536' > /proc/sys/vm/freepages > > makes a difference?
I've been using '512 1024 2048' for the last series of tests. I suppose that's ok as well, or isn't it ?
Arnaud
-- Arnaud Installe <ainstalle@filepool.com>
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