X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=docs%2Ftroubleshooting%2Freportingissues%2Freportingissues.rst;h=9192e20f49e88de246200d4e12855b78b5741a33;hb=328631d4eeac808d761471777f2bea5e64387e5e;hp=261dec9013a4c012e60c4df07cd98d0512a9191b;hpb=b93452b531f8c4d3fdcd77a3b3c8ede1a511cbc6;p=vpp.git

diff --git a/docs/troubleshooting/reportingissues/reportingissues.rst b/docs/troubleshooting/reportingissues/reportingissues.rst
index 261dec9013a..9192e20f49e 100644
--- a/docs/troubleshooting/reportingissues/reportingissues.rst
+++ b/docs/troubleshooting/reportingissues/reportingissues.rst
@@ -194,9 +194,20 @@ will capture usable vpp core files in /tmp/dumps.
     # ulimit -c unlimited
     # echo 2 > /proc/sys/fs/suid_dumpable
 
-Vpp core files often appear enormous. Gzip typically compresses them
-to manageable sizes. A multi-GByte corefile often compresses to 10-20
-Mbytes.
+If you start VPP from systemd, you also need to edit
+/lib/systemd/system/vpp.service and uncomment the "LimitCORE=infinity"
+line before restarting VPP.
+
+Vpp core files often appear enormous, but they are invariably
+sparse. Gzip compresses them to manageable sizes. A multi-GByte
+corefile often compresses to 10-20 Mbytes.
+
+When decompressing a vpp core file, we suggest using "dd" as shown to
+create a sparse, uncompressed core file:
+
+.. code-block:: console
+
+   $ zcat vpp_core.gz | dd conv=sparse of=vpp_core
 
 Please remember to put compressed core files in accessible places.
 
@@ -205,6 +216,9 @@ Make sure to leave the default stanza "... unix { ... full-coredump
 /etc/vpp/startup.conf, or to include it in the command line arguments
 passed by orchestration software.
 
+Core files from Private Images
+==============================
+
 Core files from private images require special handling. If it's
 necessary to go that route, copy the **exact** Debian packages (or
 RPMs) which correspond to the core file to the same public place as
@@ -234,6 +248,33 @@ Even given a byte-for-byte identical source tree, it's easy to build
 dramatically different binary artifacts. All it takes is a different
 toolchain version.
 
+
+On-the-fly Core File Compression
+--------------------------------
+
+Depending on operational requirements, it's possible to compress
+corefiles as they are generated. Please note that it takes several
+seconds' worth of wall-clock time to compress a vpp core file on the
+fly, during which all packet processing activities are suspended.
+
+To create compressed core files on the fly, create the following
+script, e.g. in /usr/local/bin/compressed_corefiles, owned by root,
+executable:
+
+.. code-block:: console
+
+  #!/bin/sh
+  exec /bin/gzip -f - >"/tmp/dumps/core-$1.$2.gz"
+
+Adjust the kernel core file pattern as shown:
+
+.. code-block:: console
+
+  sysctl -w kernel.core_pattern="|/usr/local/bin/compressed_corefiles %e %t"
+
+Core File Summary
+-----------------
+
 Bottom line: please follow core file handling instructions to the
 letter. It's not complicated. Simply copy the exact Debian packages or
 RPMs which correspond to core files to accessible locations.