I had plenty of time this weekend so i have been doing a _lot_ of
testing. My next emails will send a set of patches:
Patch 1: Introduces explicit tx locking
Patch 2: Introduces batching interface
Patch 3: Core uses batching interface
Patch 4: get rid of dev->gso_skb
Testing
-------
Each of these patches has been performance tested and the results
are in the logs on a per-patch basis.
My system under test hardware is a 2xdual core opteron with a couple of
tg3s.
My test tool generates udp traffic of different sizes for upto 60
seconds per run or a total of 30M packets. I have 4 threads each
running on a specific CPU which keep all the CPUs as busy as they can
sending packets targetted at a directly connected box's udp discard
port.
All 4 CPUs target a single tg3 to send. The receiving box has a tc rule
which counts and drops all incoming udp packets to discard port - this
allows me to make sure that the receiver is not the bottleneck in the
testing. Packet sizes sent are {64B, 128B, 256B, 512B, 1024B}. Each
packet size run is repeated 10 times to ensure that there are no
transients. The average of all 10 runs is then computed and collected.
I have not run testing on patch #4 because i had to let the machine
go, but will have some access to it tommorow early morning where i can
run some tests.
Comments
--------
Iam trying to kill ->hard_batch_xmit() but it would be tricky to do
without it for LLTX drivers. Anything i try will require a few extra
checks. OTOH, I could kill LLTX for the drivers i am using that
are LLTX and then drop that interface or I could say "no support
for LLTX". I am in a dilema.
Dave please let me know if this meets your desires to allow devices
which are SG and able to compute CSUM benefit just in case i
misunderstood.
Herbert, if you can look at at least patch 4 i will appreaciate it.
More patches to follow - i didnt want to overload people by dumping
too many patches. Most of these patches below are ready to go; some are
need some testing and others need a little porting from an earlier
kernel:
- tg3 driver (tested and works well, but dont want to send
- tun driver
- pktgen
- netiron driver
- e1000 driver
- ethtool interface
- There is at least one other driver promised to me
I am also going to update the two documents i posted earlier.
Hopefully i can do that today.
cheers,
jamal
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