Felipe Martinez Hermo wrote:
Scott Lovenberg escribió:
On Feb 6, 2008 4:19 AM, Felipe Martinez Hermo <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Sinisa Bandin escribió:
>
>
> Felipe Martinez Hermo wrote:
>>
>>>> OK, so we're apples to apples, so to speak; the servers are
tuned
>>>> the same. I'll assume your disks are tuned from hdparm and
up to
>>>> snuff, otherwise you wouldn't be tuning sockets ;). Did
your old
>>>> server have samba settings for oplocks set?
>>>>
>>>>
>>>> --
>>>> Peace and Blessings,
>>>> -Scott.
>>>>
>>>> "Of course, that's just my opinion; I could be wrong"
>>>> -Dennis Miller
>>> Erm, sorry, I didn't catch that you had 2 .conf files there.
I'm
>>> back to the drawing board. Sorry about that. Anyone else
have any
>>> ideas?
>> Yes, that's whats shocking me. Apparently we're apples to apples.
>> Except for the kernel (new&slow 2.6.18-4-686 vs old&fast 2.6.8)
>>
>> I've sniffed both eth0 interfaces and I've got some more
information.
>> When talking to the slow server, the client needs to send 76 "TCP
>> segment of a reassembled PDU" that are not sent when talking
to the
>> old and fast server.
>>
>> How can I workaround this issue? Should I lower server's MTU?
How much?
>>
>> Thank you
> Do you happen to have a Realtek 8169 based gigabit ethernet in new
> server?
>
> If you do, I had the same problem several times last year, and
solved
> all of them by changing motherboards (all were integrated, and I
like
> them to stay that way because I can achieve full gigabit speed
with
> several concurent clients)
>
> Best regards,
> Sinisa Bandin
>
>
No, machines are out-of-the-box HP DL servers:
Ethernet controller: Broadcom Corporation NetXtreme BCM5705_2
Gigabit
Ethernet (rev 03)
I've made a spreadsheet with summarizing wireshark results and
comparing
results for both servers. You can see it here:
http://spreadsheets.google.com/ccc?key=pnLL2fInqFq2YKuZIphtQdA
It's meaningful that fast server makes 406 Trans2 calls, while slow
server makes 616 calls to perform the same operation. The
difference is
mainly in QUERY_PATH_INFO (200 vs 305) and FIND_FIRST2 (94 vs 199)
calls.
Next try: change ethernet wire? :-?
--
==============================
Felipe Martínez Hermo
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
==============================
Servicios Informáticos
UGT Galicia
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
==============================
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Hrm, are you using SACKs or DSACKs or tcp_low_delay in
/proc/sys/net/somethingOrOther? They didn't change congestion
control default in your upstream kernel, did they? Should be "reno"
by default. Doing a netstat -a, do you have many packets queued in
either direction? This one is puzzling me.
--
Peace and Blessings,
-Scott.
Apparently everything is configured the same way in /proc/sys/net
(both sack & dsack = 1). Regarding the kernel, Old&fast kernel is
2.6.8 (no /proc/sys/net/ipv4/tcp_congestion_control) while new&slow is
2.6.18-4-686 and congestion control is bic:
[EMAIL PROTECTED]:~$ cat /proc/sys/net/ipv4/tcp_congestion_control
bic
Should I try other congestion control algorithm?
I've made this rudimentary test, and old server is a little bit
faster, but I don't know if it is meaningful at all.
[EMAIL PROTECTED]:~$ ping -i 0.2 fast_server --- fast_server ping
statistics ---
2156 packets transmitted, 2156 received, 0% packet loss, time 431208ms
rtt min/avg/max/mdev = 0.135/0.171/0.245/0.018 ms
[EMAIL PROTECTED]:~$ ping -i 0.2 slow_server
--- slow_server ping statistics ---
2146 packets transmitted, 2146 received, 0% packet loss, time 429165ms
rtt min/avg/max/mdev = 0.152/0.179/0.333/0.021 ms
Regards,
try:
echo "reno" > /proc/sys/net/ipv4/tcp_congestion_control
That'll make sure the tcp/ip stack isn't messing with the tests by doing
window scaling and such. OK, that's one more variable isolated... let's
see what happens. Sorry that this is taking to long to troubleshoot;
I'm an armchair administrator. Actually I'm a software development
major in college, but either way, I'm a bit out of my element as
compared to the professional administrators.
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