[Bug 1951032] Autopkgtest regression report (glibc/2.31-0ubuntu9.4)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted glibc (2.31-0ubuntu9.4) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

snapd-glib/1.58-0ubuntu0.20.04.0 (armhf)
apt/2.0.6 (armhf)
libmath-mpfr-perl/4.13-1 (armhf)
art-nextgen-simulation-tools/20160605+dfsg-4 (armhf)
ruby-nokogiri/1.10.7+dfsg1-2build1 (armhf)
r-cran-rgdal/1.4-8-1build2 (armhf)
arrayfire/3.3.2+dfsg1-4ubuntu4 (armhf)
libpango-perl/1.227-3build1 (armhf)
libimage-sane-perl/5-1 (s390x)
ruby-bootsnap/1.4.6-1 (arm64)
mle/1.4.3-1 (ppc64el, arm64)
libsyntax-keyword-try-perl/0.11-1build1 (armhf)
awesome/4.3-4 (armhf)
cysignals/1.10.2+ds-4 (arm64)
gvfs/1.44.1-1ubuntu1 (ppc64el)
libuv1/1.34.2-1ubuntu1.3 (amd64)
bali-phy/3.4.1+dfsg-2build1 (arm64, s390x)
g10k/0.5.7-1 (armhf)
litl/0.1.9-7 (amd64)
ruby-libxml/3.1.0-2 (armhf)
ffmpeg/7:4.2.4-1ubuntu0.1 (armhf)
yorick/2.2.04+dfsg1-10 (ppc64el, s390x)
linux-ibm/5.4.0-1010.11 (amd64)
liborcus/0.15.3-3build2 (armhf)
node-nodedbi/1.0.13+dfsg-1build1 (amd64)
r-bioc-delayedarray/0.12.2+dfsg-1 (armhf)
postgresql-unit/7.2-2 (armhf)
python-freecontact/1.1-5build2 (armhf)
r-cran-rwave/2.4-8-2 (armhf)
libproc-fastspawn-perl/1.2-1build2 (armhf)
linux-hwe-5.11/5.11.0-44.48~20.04.2 (armhf)
foo2zjs/20171202dfsg0-4 (armhf)
r-cran-erm/1.0-0-1 (armhf)
libsys-cpuload-perl/0.03-8build5 (armhf)
libhttp-parser-xs-perl/0.17-1build5 (armhf)
php-luasandbox/3.0.3-2build2 (armhf)
pynfft/1.3.2-3build1 (armhf)
r-cran-processx/3.4.2-1 (ppc64el)
r-bioc-multtest/2.42.0-1 (armhf)
linux-hwe-5.13/5.13.0-23.23~20.04.2 (armhf)
python-blosc/1.7.0+ds1-2ubuntu2 (armhf)
gyoto/1.4.4-3 (armhf)
r-cran-sem/3.1.9-2build1 (armhf)
libtext-reflow-perl/1.17-1build3 (armhf)
python3.9/3.9.5-3ubuntu0~20.04.1 (armhf)
r-cran-samr/3.0-1 (armhf)
r-cran-dplyr/0.8.4-1 (armhf)
python3.8/3.8.10-0ubuntu1~20.04.2 (armhf)
findent/3.1.1-1build1 (armhf)
mercurial/5.3.1-1ubuntu1 (amd64)
libmemcached-libmemcached-perl/1.001801+dfsg-2build4 (armhf)
openbabel/3.0.0+dfsg-3ubuntu3 (armhf)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/focal/update_excuses.html#glibc

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/1951032

Title:
  AArch64: Backport memcpy improvements

Status in glibc package in Ubuntu:
  Fix Released
Status in glibc source package in Focal:
  Fix Committed

Bug description:
  [impact]
  glibc 2.32 contained a number of improvements to the memcpy routines for server-grade AArch64 implementations (in particular, graviton2 & graviton3). They should be backported to focal, as the LTS releases are by far the most used on servers.

  [test case]
  Compile the test_memcpy.c that is attached to bug 1928508:

  $ gcc -g -O3 test_memcpy.c -o test_memcpy64

  This should be run before and after installing the libc packages from
  proposed. On graviton2 systems, this should show a substantial
  improvement. On other arm64 systems (raspberry pis of various vintage,
  thunderx2, xgene, etc etc) at least no significant regression should
  be seen.

  [regression potential]
  Rebuilding glibc is always a little risky (toolchain bugs and incompatibilities between the old and new versions can be surprising). But the autopkgtests and some manual general testing can help here.

  For this specific change, there is a potential risk that the new
  memcpy implementation could be used on a system where it is not in
  fact the fastest. We should run the test case not only on the systems
  where it is expected to help, but other systems such as the RPi4 and
  the launchpad build farm to ensure performance is not regressed there.

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