[Samba] Aplication slow after migration

[Felipe Martinez Hermo]

Scott Lovenberg escribió:
>
>
> On Feb 6, 2008 4:19 AM, Felipe Martinez Hermo <felipe at galicia.ugt.org 
> <mailto:felipe at galicia.ugt.org>> 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
>     felipe at galicia.ugt.org <mailto:felipe at galicia.ugt.org>
>     fmartinez at galicia.ugt.org <mailto:fmartinez at galicia.ugt.org>
>     ==============================
>     Servicios Informáticos
>     UGT Galicia
>     informatica at galicia.ugt.org <mailto:informatica at galicia.ugt.org>
>     ugtgalicia at gmail.com <mailto:ugtgalicia at gmail.com>
>     ==============================
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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:

ugtgalicia at max:~$ 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.

felipe at nils:~$ 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

felipe at nils:~$ 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,

-- 
==============================
Felipe Martínez Hermo
felipe at galicia.ugt.org
fmartinez at galicia.ugt.org
==============================
Servicios Informáticos
UGT Galicia
informatica at galicia.ugt.org
ugtgalicia at gmail.com
==============================