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[Mathew Hodson <1861177@xxxxxxxxxxxxxxxxxx>]

** Project changed: snapd => ubuntu-translations

** No longer affects: ubuntu-translations

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https://bugs.launchpad.net/bugs/1861177

Title:
  seccomp_rule_add is very slow

Status in libseccomp package in Ubuntu:
  Fix Released
Status in libseccomp source package in Xenial:
  Fix Released
Status in libseccomp source package in Bionic:
  Fix Released
Status in libseccomp source package in Eoan:
  Won't Fix
Status in libseccomp source package in Focal:
  Fix Released
Status in libseccomp source package in Groovy:
  Fix Released

Bug description:
  [IMPACT]
  There is a known and patched issue with version 2.4 of libseccomp where certain operations have a large performance regression. This is causing some packages that use libseccomp such as container orchestration systems to occasionally time out or otherwise fail under certain workloads.

  Please consider porting the patch into the various Ubuntu versions
  that have version 2.4 of libseccomp and into the backports. The
  performance patch from version 2.5 (yet to be released) applies
  cleanly on top of the 2.4 branch of libseccomp.

  For more information, and for a copy of the patch (which can also be
  cherry picked from the upstream libseccomp repos) see the similar
  Debian issue: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=943913

  Upstream issue : https://github.com/seccomp/libseccomp/issues/153
  Upstream fix : https://github.com/seccomp/libseccomp/pull/180/

  [Test Case]

  For this test case we use Docker on Ubuntu Groovy (20.10) :

  --> Current libseccomp version
  #dpkg -l | grep libseccomp
  ii  libseccomp2:amd64                          2.4.3-1ubuntu3                      amd64        high level interface to Linux seccomp filter

  ## pull ubuntu image
  # docker pull ubuntu
  ## create a container
  # docker run --name test_seccomp -it 74435f89ab78 /bin/bash

  ## run test case
  # for i in `seq 1 40`; do (time sudo docker exec test_seccomp true &); done
  ...
  MAX TIME :
  real	0m10,319s
  user	0m0,018s
  sys	0m0,033s

  
  --> Patched libseccomp version

  # dpkg -l | grep libseccomp
  ii  libseccomp2:amd64                          2.4.3-1ubuntu4                      amd64        high level interface to Linux seccomp filter

  # docker start test_seccomp
  ## run test case
  # for i in `seq 1 40`; do (time sudo docker exec test_seccomp true &); done
  ...
  MAX TIME :
  real	0m3,650s
  user	0m0,025s
  sys	0m0,028s

  [Regression Potential]

  The first of the 2 patches cleans up the code that adds rules to a
  single filter without changing the logic of the code. The second patch
  introduces the idea of shadow transactions. On a successful
  transaction commit the old transaction checkpoint is preserved and is
  brought up to date with the current filter. The next time a new
  transaction starts, it checks is the a shadow transaction exist and if
  so the shadow is used instead of creating a new checkpoint from
  scratch [1]. This is the patch that mitigates the performance
  regression. Any potential regression will involve the parts of the
  code that add rules to filters and/or the code that creates and checks
  the shadow transactions.

  
  [Other]

  Affected releases : Groovy, Focal, Eoan, Bionic, Xenial.

  [1]
  https://github.com/seccomp/libseccomp/pull/180/commits/bc3a6c0453b0350ee43e4925482f705a2fbf5a4d

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