Date: Thu, 18 Mar 1999 21:25:12 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Bill Paul <wpaul@skynet.ctr.columbia.edu> Cc: hackers@FreeBSD.ORG Subject: Re: Gigabit ethernet revisited Message-ID: <199903190525.VAA44097@apollo.backplane.com> References: <199903190356.WAA02769@skynet.ctr.columbia.edu>
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:it's about half what I think it should be. The nic stats counters
:show quite a few nicDmaWriteRingFull and nicNoMoreWrDMADescriptors
:errors, which means that the NIC is receiving the frames but the
:bus isn't transfering them to the host fast enough.
:
:The machines I'm using now are Dell Precision 410 workstations, each
:with one 450Mhz Pentium II CPU, 128MB of RAM and Intel 82443BX PCI
:chipsets.
It sounds like the DMA is working fine, but the host computer
is not able to drain the receive ring ( which I presume is the
'write ring' ) quickly enough.
Your current code appears to allocate a sufficient number of buffers,
but your ti_refill_rx_rings() optimization is suspect... you do not
call it until you have *COMPLETELY* drained the RX ring of packets.
What happens if new packets are streaming in faster then you can drain
them? You will completely exhaust your RX ring before you reallocate
it's buffers.
I would also suggest figuring out *exactly* why you are getting the
error message... i.e. is the RX ring actually completely used up as of
the time the error occurs?
-Matt
Matthew Dillon
<dillon@backplane.com>
:http://www.freebsd.org/~wpaul/Alteon/3.0/tigon.tar.gz. The manuals
:for the Tigon chip are at http://www.alteon.com/support/openkits.
:
:-Bill
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