Messages in this thread | | | Date | Sun, 9 Aug 1998 03:21:58 +0200 | From | Andi Kleen <> | Subject | Re: 100Mbps TCP stalls in 2.1.115 |
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On Sun, Aug 09, 1998 at 02:36:49AM +0200, Zlatko Calusic wrote: > Andi Kleen <ak@muc.de> writes: > > > Zlatko Calusic <Zlatko.Calusic@CARNet.hr> writes: > > > > > > E. g. FTP between two 100mbit hosts, transfer rate is ~50kb/sec, but > > > many times it recovers after few (or few tens of) seconds. > > > > > > Sometimes it works, sometimes not. Tcpdump logs available on request. > > > > > > Any clue? > > > > What does /proc/net/netstat say after such a stall? > > {atlas} [~]% cat /proc/net/netstat > TcpExt: SyncookiesSent SyncookiesRecv SyncookiesFailedEmbryonicRsts > TcpExt: 0 0 0 0
You need a kernel >= 2.1.114 for useful output, sorry.
> > > > Also could you try to reproduce it with sockets that have the SO_DEBUG > > flag set ? > > > > I should take my favorite TCP application and recompile with one > additional setsockopt in code, am I right? > I never did SO_DEBUG's. :) > > I noticed that stalls are periodical, with period of about 2-3 > minutes. > > I made a long ping session, and came up with this: > > PING div.srce.hr (161.53.3.13): 56 data bytes > 64 bytes from 161.53.3.13: icmp_seq=0 ttl=253 time=1.3 ms > 64 bytes from 161.53.3.13: icmp_seq=1 ttl=253 time=1.1 ms > 64 bytes from 161.53.3.13: icmp_seq=2 ttl=253 time=1.1 ms > 64 bytes from 161.53.3.13: icmp_seq=3 ttl=253 time=1.0 ms > 64 bytes from 161.53.3.13: icmp_seq=4 ttl=253 time=1.1 ms > ... everything's ok, when ping times are around 1ms > 64 bytes from 161.53.3.13: icmp_seq=147 ttl=253 time=1.0 ms > 64 bytes from 161.53.3.13: icmp_seq=148 ttl=253 time=1.0 ms > ... from now on, things are dog slow... > 64 bytes from 161.53.3.13: icmp_seq=150 ttl=253 time=2.1 ms > 64 bytes from 161.53.3.13: icmp_seq=151 ttl=253 time=2.0 ms > 64 bytes from 161.53.3.13: icmp_seq=152 ttl=253 time=2.0 ms > 64 bytes from 161.53.3.13: icmp_seq=153 ttl=253 time=2.1 ms > 64 bytes from 161.53.3.13: icmp_seq=154 ttl=253 time=2.1 ms > 64 bytes from 161.53.3.13: icmp_seq=155 ttl=253 time=2.1 ms > 64 bytes from 161.53.3.13: icmp_seq=156 ttl=253 time=2.1 ms > 64 bytes from 161.53.3.13: icmp_seq=157 ttl=253 time=74.9 ms > 64 bytes from 161.53.3.13: icmp_seq=158 ttl=253 time=28.1 ms > 64 bytes from 161.53.3.13: icmp_seq=161 ttl=253 time=2.2 ms > 64 bytes from 161.53.3.13: icmp_seq=163 ttl=253 time=2.1 ms > ... > 64 bytes from 161.53.3.13: icmp_seq=335 ttl=253 time=2.1 ms > 64 bytes from 161.53.3.13: icmp_seq=336 ttl=253 time=2.0 ms > ... from now on, things are working correctly again... > 64 bytes from 161.53.3.13: icmp_seq=337 ttl=253 time=1.1 ms > 64 bytes from 161.53.3.13: icmp_seq=338 ttl=253 time=1.1 ms > ... and so on...
If ping is slow too it is probably a network driver problem, not a TCP problem.
-Andi
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