On Wed, 6 Nov 2002, Ben Greear wrote:

Here's an update of the tulip-NAPI and skb-recycle patches.  I made some
changes to get it to compile and work when the RECYCLE define in skbuff.h
was not enabled.

I also got some test runs in.  Nothing really conclusive.

Test setup:  Phobos 4-port NIC in each P-IV 1.8Ghz machine 32/33 PCI bus.
Kernel 2.4.20-rc1 + my patches.  NICs connected to each other over CX cables.
Sending 4k 1514 byte packets per second, send + receive. (48Mbps or so)
RX ring size is 1024 for all of these tests.  No significant errors reported
by the driver.  I don't know where these dropped packets go..no counter
seems to be catching them.

I sent 1 million packets (or very close to that) on every interface (received
the same, mostly)

Without SKB-Recycle:
   dropped 339 out of 1Million, repeated test twice, numbers very similar.
   When packets do drop, they drop on all interfaces in bursts of 10-150, generally.
   Latency was about .3ms

With SKB-Recycle (300 pkt hot-list)
   dropped 230, 500, and 180 in consecutive runs.  They also drop in bursts.
   The middle run may be bad luck...don't know.
   Latency was about .3ms
   While typing, I ran a longer test.  Dropped about 1600 out of 4 million.

Trash the machines harder. Try using smaller packets;

cheers,
jamal