From mboxrd@z Thu Jan  1 00:00:00 1970
From: bugzilla@dpdk.org
Subject: [Bug 50] Secondary process launch is unreliable
Date: Tue, 22 May 2018 16:15:47 +0000
Message-ID: <bug-50-3@http.dpdk.org/tracker/>
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https://dpdk.org/tracker/show_bug.cgi?id=3D50

            Bug ID: 50
           Summary: Secondary process launch is unreliable
           Product: DPDK
           Version: 18.05
          Hardware: All
                OS: All
            Status: CONFIRMED
          Severity: normal
          Priority: Normal
         Component: core
          Assignee: dev@dpdk.org
          Reporter: anatoly.burakov@intel.com
  Target Milestone: ---

Secondary process initialization was known to be unreliable before, with
numerous workarounds already being available and documented. However, DPDK
version 18.05 has introduced memory subsystem rework, which has made situat=
ion
worse due to much more memory being pre-reserved at initialization.

In addition, following investigation, it was revealed that DPDK secondary
processes ran with fork()/execv() method from within another DPDK applicati=
on
(such as is the case with some DPDK unit tests) carry an additional risk of
initialization failures due to how pthread library appears to be working un=
der
these conditions. Specifically, two IPC threads created by EAL will take up=
 a
lot of address space (more than 10x of the usual amount), thereby interferi=
ng
with secondary process mappings and causing initialization failure. In this
case, disabling ASLR may actually make the situation worse, as
non-deterministic but sometimes lucky memory layout will be replaced by
deterministically wrong address mappings.

Things to try when affected by this issue:

* Using --base-virtaddr to relocate DPDK memory segments at initialization
* Not running DPDK applications using fork()/execv() method
* Enabling or disabling ASLR
* Recompiling the binary with different configuration
* Reducing the amount of preallocated memory (adjusting config options
CONFIG_RTE_MAX_MEM_MB_PER_TYPE and/or RTE_MAX_MEM_MB_PER_LIST)

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