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<DIV>can you post your netstat –s on one of your servers that is having the
problem?</DIV>
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<DIV style="font-color: black"><B>From:</B> <A title=mrk191@gmail.com
href="mailto:mrk191@gmail.com">Michael Krysiak</A> </DIV>
<DIV><B>Sent:</B> Saturday, June 22, 2013 7:00 AM</DIV>
<DIV><B>To:</B> <A title=kernelnewbies@kernelnewbies.org
href="mailto:kernelnewbies@kernelnewbies.org">kernelnewbies@kernelnewbies.org</A>
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<DIV><B>Subject:</B> High Latency during packet transmission</DIV></DIV></DIV>
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<DIV dir=ltr><SPAN style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif">I've
been trying to identify why we're seeing frequent stalls during packet
transmission in our GPFS cluster in the bnx2 driver (as well as other
NICs/drivers), but I am at the limit of my current knowledge. I used perf
netdev events (as described in </SPAN><A
style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif"
href="http://lwn.net/Articles/397654/"
target=_blank>http://lwn.net/Articles/397654/</A><SPAN
style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif">) to measure the tx
times, and see spikes such as the following:</SPAN>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif"> </DIV>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif"><FONT
face="courier new, monospace"> dev
len
Qdisc
netdevice
free<BR></FONT></DIV>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif">
<DIV><FONT face="courier new, monospace">
em2 98
807740.878085sec
0.002msec
0.061msec</FONT></DIV>
<DIV><FONT face="courier new, monospace">
em2 98
807740.878119sec
0.002msec
0.029msec</FONT></DIV>
<DIV><FONT face="courier new, monospace">
em2 98
807741.140600sec
0.005msec
0.092msec</FONT></DIV>
<DIV><FONT face="courier new, monospace"> em2 65226
807742.763833sec
0.007msec
0.436msec</FONT></DIV>
<DIV><FONT face="courier new, monospace">
em2 66
807727.081712sec
0.001msec
16246.072msec</FONT></DIV>
<DIV><FONT face="courier new, monospace">
em2 66
807740.882741sec
0.001msec
3457.625msec</FONT></DIV></DIV>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif"> </DIV>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif"> </DIV>
<DIV style="FONT-SIZE: 13px; FONT-FAMILY: arial,sans-serif">Based on the source
for netdev-times.py, the "free" column is the difference between
trace_net_dev_xmit() and trace_kfree_skb() in net/core/dev.c, but I'm not sure
how to dig any deeper. Are there any common causes for this
behavior? What's the best way to further break down the time difference
between the xmit and kfree trace points?</DIV></DIV>
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