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Message #131661
[Bug 1537635] Re: Reduce zlib compression level for massive performance increase
** Tags added: rls-x-incoming
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https://bugs.launchpad.net/bugs/1537635
Title:
Reduce zlib compression level for massive performance increase
Status in Apport:
New
Status in apport package in Ubuntu:
Confirmed
Bug description:
When apport takes a core dump of a large application, it uses 100% CPU
for a _long_ time (often 30 seconds or more) to compress the core
dump. The system is virtually unusable during this time, especially if
the application was the window manager and won’t be restarted until
the core dump is complete.
This is a longstanding known problem; it motivated the switch from
bzip2 to zlib level 9 back in apport 0.24. That made it much better,
but it’s still quite bad. So why not switch from zlib level 9 to zlib
level 1?
I tested this on a core dump of gnome-shell, and while it increased
the size of the .crash file by 24% (68.5 MB to 85.0 MB), it decreased
the needed CPU time by a FACTOR OF EIGHT (58.6 seconds to 7.3
seconds). This tradeoff seems more than worthwhile for this use case.
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References