[kronosnet/kronosnet] 1dfc82: [PMTUd] fix external API and PMTUd interaction - Commits

19 Dec 2017


      Branch: refs/heads/master
  Home:   https://github.com/kronosnet/kronosnet
  Commit: 1dfc8220a3f090e5ca6f8b922c63ae64e09260d1
      https://github.com/kronosnet/kronosnet/commit/1dfc8220a3f090e5ca6f8b922c63ae...
  Author: Fabio M. Di Nitto fdinitto@redhat.com
  Date:   2017-12-18 (Mon, 18 Dec 2017)
Changed paths:
    M libknet/handle.c
    M libknet/host.c
    M libknet/internals.h
    M libknet/links.c
    M libknet/logging.c
    M libknet/tests/Makefile.am
    M libknet/threads_common.c
    M libknet/threads_common.h
    M libknet/threads_dsthandler.c
    M libknet/threads_pmtud.c
    M libknet/transport_sctp.c
    M libknet/transports.c
Log Message:
  -----------
  [PMTUd] fix external API and PMTUd interaction
The problem:
PMTUd can take a long time to release the global read lock, mostly due
to the pthread_cond_timedwait required to ack/nack packets from the
other hosts. This delay could block any wrlock operation for several seconds
if not more.
The solution:
each call to the global pthread_rwlock_wrlock has been changed to a wrapper
that will notify the PMTUd to interrupt its operations (and restart) first,
then get a global write lock that is queued as soon as PMTUd is going out.
This solution also improves a lot shutdown speed.
How to test:
This is not super simple to test and verify. I used 2 VMs with known MTU of
1500. Start knet_bench on both (normal ping_data -C is more than enough).
Once they have established data exchange, change the MTU on one of the nodes
to 1600 (or higher). This should guarantee that the PMTUd process will take
a very long time to complete.
First verify that the PMTUd process takes several seconds.
Once the next PMTUd run starts, hit ctrl+c on the node that is executing
the PMTUd and the process should exit much faster than before this patch.
Signed-off-by: Fabio M. Di Nitto fdinitto@redhat.com
Commit: f8465e758969e2d4d9b5ed4a486890499419fb09
      https://github.com/kronosnet/kronosnet/commit/f8465e758969e2d4d9b5ed4a486890...
  Author: Fabio M. Di Nitto fdinitto@redhat.com
  Date:   2017-12-19 (Tue, 19 Dec 2017)
Changed paths:
    M libknet/handle.c
    M libknet/host.c
    M libknet/internals.h
    M libknet/links.c
    M libknet/logging.c
    M libknet/tests/Makefile.am
    M libknet/threads_common.c
    M libknet/threads_common.h
    M libknet/threads_dsthandler.c
    M libknet/threads_pmtud.c
    M libknet/transport_sctp.c
    M libknet/transports.c
Log Message:
  -----------
  Merge pull request #103 from kronosnet/mtu-lock
[PMTUd] fix external API and PMTUd interaction
Compare: https://github.com/kronosnet/kronosnet/compare/0915310bc3da...f8465e758969