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tcp.setsockopt probe seems to be returning incorrect optval
- From: "MacCana, Mike" <mike dot maccana at credit-suisse dot com>
- To: <systemtap at sources dot redhat dot com>
- Date: Thu, 25 Mar 2010 14:48:58 -0000
- Subject: tcp.setsockopt probe seems to be returning incorrect optval
Hi SystemTap folks,
I have a simple stap I'm documenting (see
http://sourceware.org/systemtap/wiki/WSTCPSocketOptions
<http://sourceware.org/systemtap/wiki/WSTCPSocketOptions> ) to find apps
that use the TCP_NODELAY option on their sockets.
When I run:
probe tcp.setsockopt
{
printf (" App '%s' (PID %d) set socket option %s with value %d ...",
execname(), pid(), optstr, optval) }
I always get the result:
App 'python2.4' (PID 29279) set socket option TCP_NODELAY with value 0
...success
When when my app is setting the value to true, not false:
mysocket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
So optval doesn't seem to be the value I understand it is from the docs
- does anyone have any ideas why, or how I can get my stap to report the
correct value ?
Thanks,
Mike MacCana
Mike MacCana
Engineer
RDO Low Latency Infrastructure
CREDIT SUISSE
Phone: +44 (0)20 7883 5907
Mobile: +44 (0)7547 004474
mike.maccana@credit-suisse.com
Five Canada Square, London, E14 4QJ.
www.credit-suisse.com
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