[Big list of testing , rebuilding kernel follows]

Dual Opteron 2212, Recompiled kernel with 7-STABLE and removed a lot of junk in the config, added options NO_ADAPTIVE_MUTEXES not sure if that makes any difference or not, will test without.
Used ULE scheduler, used preemption, CPUTYPE=opteron in /etc/make.conf
7.0-STABLE FreeBSD 7.0-STABLE #4: Tue Jul  1 01:22:18 CDT 2008 amd64
Max input rate .. 587kpps? Take into consideration that these packets are being forwarded out em1 interface which causes a great impact on cpu usage. If I set up a firewall rule to block the packets it can do over 1mpps on em0 input.

          input          (em0)           output
  packets  errs      bytes    packets  errs      bytes colls
   587425 67677   35435456        466     0      25616     0
   587412 26629   35434766        453     0      24866     0
   587043 26874   35412442        410     0      22544     0
   536117 30264   32347300        440     0      24164     0
   546240 61521   32951060        459     0      25350     0
   563568 66881   33998676        435     0      23894     0
   572766 43243   34550840        440     0      24164     0
   572336 44411   34525836        445     0      24558     0
   572539 37013   34536222        457     0      25136     0
   571340 39512   34459008        440     0      24110     0
   572673 55137   34540576        438     0      24056     0
   555506 49918   33505764        457     0      25330     0
   545744 69010   32916908        461     0      25298     0
   559472 75650   33745636        429     0      23694     0
   564358 60130   34039104        433     0      23786     0

last pid: 1134; load averages: 1.04, 0.94, 0.59 up 0+00:14:13 01:49:59
70 processes:  6 running, 46 sleeping, 17 waiting, 1 lock
CPU:  0.0% user,  0.0% nice, 25.6% system,  0.0% interrupt, 74.4% idle
Mem: 11M Active, 6596K Inact, 45M Wired, 156K Cache, 9072K Buf, 1917M Free
Swap: 8192M Total, 8192M Free

 PID USERNAME PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
  12 root     171 ki31     0K    16K RUN    1  12:40 97.56% idle: cpu1
  36 root     -68    -     0K    16K *em1   2   9:44 85.06% em0 taskq
  10 root     171 ki31     0K    16K CPU3   3  11:10 82.47% idle: cpu3
  13 root     171 ki31     0K    16K CPU0   0  12:25 73.88% idle: cpu0
  11 root     171 ki31     0K    16K RUN    2   6:43 50.10% idle: cpu2
  37 root     -68    -     0K    16K CPU3   3   1:58 16.46% em1 taskq


I noticed.. em0 taskq isn't using 100% cpu like it was on the generic kernel.. What's up with that? Why do I still have all 4 CPUs pretty idle and em0 taskq isn't near 100%? I'm going to try 4bsd and see if that makes it go back to the other way.

em0: Excessive collisions = 0
em0: Sequence errors = 0
em0: Defer count = 0
em0: Missed Packets = 45395545
em0: Receive No Buffers = 95916690
em0: Receive Length Errors = 0
em0: Receive errors = 0
em0: Crc errors = 0
em0: Alignment errors = 0
em0: Collision/Carrier extension errors = 0
em0: RX overruns = 2740181
em0: watchdog timeouts = 0
em0: RX MSIX IRQ = 0 TX MSIX IRQ = 0 LINK MSIX IRQ = 0
em0: XON Rcvd = 0
em0: XON Xmtd = 0
em0: XOFF Rcvd = 0
em0: XOFF Xmtd = 0
em0: Good Packets Rcvd = 450913688
em0: Good Packets Xmtd = 304777
em0: TSO Contexts Xmtd = 94
em0: TSO Contexts Failed = 0

-----Rebooting with:
kern.hz=2000
hw.em.rxd=512
hw.em.txd=512

Seems maybe a little bit slower but it's hard to tell since i'm generating random packets the pps varies about 50k +/- probably depending
on the randomness..  About the same PPS/errors.. here's a vmstat 1
procs      memory      page                    disks     faults         cpu
r b w avm fre flt re pi po fr sr ad4 ad6 in sy cs us sy id 0 0 1 52276K 1922M 286 0 1 0 277 0 0 0 7686 838 19436 0 15 85 0 0 0 52276K 1922M 0 0 0 0 0 0 0 0 13431 127 33430 0 27 73 0 0 0 52276K 1922M 0 0 0 0 0 0 0 0 13406 115 33222 0 27 73 0 0 0 52276K 1922M 0 0 0 0 0 0 0 0 13430 115 33393 0 26 74 0 0 0 52276K 1922M 0 0 0 0 0 0 0 0 13411 115 33322 0 26 74 0 0 0 52276K 1922M 0 0 0 0 0 0 0 0 13576 123 33415 0 25 75 0 0 0 52276K 1922M 0 0 0 0 0 0 0 0 13842 115 33354 0 26 74

------Trying kern.kz=250
procs      memory      page                    disks     faults         cpu
r b w avm fre flt re pi po fr sr ad4 ad6 in sy cs us sy id 0 0 1 52288K 1923M 607 1 2 0 582 0 0 0 4885 789 12073 0 8 92 0 0 0 52288K 1923M 0 0 0 0 0 0 0 0 13793 119 33552 0 27 73 0 0 0 52288K 1923M 0 0 0 0 0 0 0 0 13959 115 33446 0 26 74 0 0 0 52288K 1923M 0 0 0 0 0 0 0 0 13861 115 33707 0 30 70 0 0 0 52288K 1923M 0 0 0 0 0 0 0 0 13784 115 33602 0 26 74 0 0 0 52288K 1923M 0 0 0 0 0 0 0 0 13886 123 33843 0 26 74 0 0 0 52288K 1923M 0 0 0 0 0 0 0 0 13913 115 33711 0 26 74 0 0 0 52288K 1923M 0 0 0 0 0 0 0 0 13920 115 33766 0 27 73

pps still no major difference..
jumps between 530k-580k

-----Putting HZ back to 1000,
recompiling kernel with 4BSD SCHED..
many minutes later.. (can't do make -j with the kernel or it errors)
Well, I have to say.. 4BSD is less pps, it will not go over 530k however it seems much, more consistent and not jumping around as much it stays between 520-530 most of the time and i see some ticks
at 480's in netstat..
em0 taskq still not using 100%, max around 75-80

-----Building same as above but with preemption off
procs      memory      page                    disks     faults         cpu
r b w avm fre flt re pi po fr sr ad4 ad6 in sy cs us sy id 0 0 0 52288K 1922M 563 1 2 0 540 0 0 0 6724 725 22195 0 12 88 0 0 0 52288K 1922M 0 0 0 0 0 0 0 0 13200 119 48075 0 27 73 0 0 0 52288K 1922M 0 0 0 0 0 0 0 0 13243 123 49137 0 24 76 0 0 0 52288K 1922M 0 0 0 0 0 0 0 0 13260 115 48633 0 26 74 0 0 0 52288K 1922M 0 0 0 0 0 0 0 0 13247 115 48625 0 25 75 0 0 0 52288K 1922M 0 0 0 0 0 0 0 0 13248 115 48687 0 24 76

hmm more context switches..
pps same, maybe a shade lower..

PID USERNAME PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
  11 root     171 ki31     0K    16K RUN    2   3:39 97.12% idle: cpu2
  12 root     171 ki31     0K    16K CPU1   1   3:45 95.70% idle: cpu1
  36 root     -68    -     0K    16K CPU0   0   2:18 82.67% em0 taskq
  10 root     171 ki31     0K    16K CPU3   3   3:24 82.57% idle: cpu3
  13 root     171 ki31     0K    16K RUN    0   2:01 20.07% idle: cpu0
  37 root     -68    -     0K    16K -      3   0:31 15.58% em1 taskq


-------rebuilding with ULE, keeping preemption off
Hmm.. what the?
450-480kpps seems to be max here.  That's.. weird..
I'm going to have to rebuild with Preemption on again just to double check this..
         input          (em0)           output
  packets  errs      bytes    packets  errs      bytes colls
   464020 95690   28009004        434     0      23728     0
   455318 90105   27484456        469     0      25778     0
   455720 99914   27511970        462     0      25384     0
   465019 86021   28071946        428     0      23392     0
   456024 78336   27528862        440     0      24040     0
   455018 93526   27468908        440     0      24040     0
   461235 91218   27841604        464     0      25336     0
   454345 89812   27427262        424     0      23176     0
   452661 96937   27327392        441     0      24094     0
   456584 90393   27561138        459     0      25222     0
   455021 97441   27470158        450     0      24736     0

procs      memory      page                    disks     faults         cpu
r b w avm fre flt re pi po fr sr ad4 ad6 in sy cs us sy id 0 0 1 52276K 1655M 456 1 1 0 441 0 0 0 9775 3598 26256 0 20 80 0 0 0 52276K 1655M 0 0 0 0 0 0 0 0 12817 119 33056 0 25 75 0 0 0 52276K 1655M 0 0 0 0 0 0 0 0 12700 123 32975 0 27 73 0 0 0 52276K 1655M 0 0 0 0 0 0 0 0 12659 115 32897 0 27 73


------OK I'm stumped now.. Rebuilt with preemption and ULE and preemption again and it's not doing what it did before..
How could that be? Now about 500kpps..

That kind of inconsistency almost invalidates all my testing.. why would it be so much different after trying a bunch of kernel options and rebooting a bunch of times and then going back to the original config doesn't get you what it did in the beginning..

I'll have to dig into this further.. never seen anything like it :)

Hopefully the ip_input fix will help free up a few cpu cycles.


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