Red Hat Bugzilla – Bug 619001
It sometimes takes 3 seconds to connect to a TCP server [rhel-6.0]
Last modified: 2014-06-18 04:30:30 EDT
This issue has been proposed when we are only considering blocker
issues in the current Red Hat Enterprise Linux release.
** If you would still like this issue considered for the current
release, ask your support representative to file as a blocker on
your behalf. Otherwise ask that it be considered for the next
Red Hat Enterprise Linux release. **
The difference in behaviour of RHEL5 and RHEL6 was caused by commit:
Author: Mike Galbraith <email@example.com>
Date: Wed Sep 9 15:41:37 2009 +0200
sched: Turn off child_runs_first
Set child_runs_first default to off.
It hurts 'optimal' make -j<NR_CPUS> workloads as make jobs
get preempted by child tasks, reducing parallelism.
With child_runs_first it takes longer for the backlog of the listening socket to fill.
Still, this is an application bug. The reason for some packets being dropped is that the backlog limit is reached. Applications increasing their backlog limit from the traditional limit of 128 to something that fits modern architectures will no longer be affected by this issue.