[systemd-devel] Significant performance loss caused by commit a65f06b: journal: return -ECHILD after a fork

[Lennart Poettering]

On Tue, 11.07.17 16:55, Tomasz Torcz (tomek at pipebreaker.pl) wrote:

> On Tue, Jul 11, 2017 at 04:10:38PM +0200, Lennart Poettering wrote:
> > On Tue, 11.07.17 16:07, Lennart Poettering (lennart at poettering.net) wrote:
> > > Hmm, so I run a slightly older glibc, as I haven#t updated my system
> > > in a while:
> > > 
> > > $ strace -c journalctl --since -1hour 2>&1 >/dev/null | head -10
> > > % time     seconds  usecs/call     calls    errors syscall
> > > ------ ----------- ----------- --------- --------- ----------------
> > >  25.95    0.001276           7       195           mmap
> > >  23.21    0.001141           7       164        30 open
> > >  22.29    0.001096           9       119           munmap
> > >   6.53    0.000321           2       134           close
> > >   6.10    0.000300           2       135           fstat
> > >   5.15    0.000253           5        56           mprotect
> > >   4.88    0.000240           2       102           fstatfs
> > >   2.30    0.000113           4        32           read
> > > 
> > > getpid() is nowhere to be seen in this... Seems Fedora regressed on
> > > this too recently. Meh.
> > 
> > Forgot to mention:
> > 
> > $ rpm -qa glibc
> > glibc-2.24-4.fc25.x86_64
> > 
> > Apparently, this regressed between this version and
> > glibc-2.24-9.fc25.x86_64 hence.
> > 
> 
>   From glibc changelog:
> 
> * Wed Jun 07 2017 Arjun Shankar <arjun.is at lostca.se> - 2.24-6
> - Auto-sync with upstream release/2.24/master,
>   commit 7b60553e360731338631ccdda71590ac5deca137, fixing:
> - Remove the PID cache  (#1443976)

I commented on that bug now. It doesn#t really have a proper
explanation, all it says is that "The glibc PID cache negatively
interacts with setting up containers and namespaces."...

Lennart

-- 
Lennart Poettering, Red Hat