[systemd-devel] [RFC/PATCH 3/3] coredump: compress core files

[Lennart Poettering]

On Wed, 25.06.14 07:28, Zbigniew Jędrzejewski-Szmek (zbyszek at in.waw.pl) wrote:

> Hi,
> a POC patch to compress coredumps after they are written. In my simple
> tests, this brings huge savings, because the compressed coredump can
> compress to ~5%.
> 
> Unfortunately the core is first written uncompressed, then compressed
> by reading from disk and writing to the output file. This is ugly and
> slow, but I don't see a way around, if we want to get the backtrace
> without keeping everything in memory.

I have the suspicion that there indeed is no other nice way for
this... Hence looks good to me.

> 'coredumpctl gdb' is not implemented yet (the decompression part is
> missing).

Hmm, we probably should add a coredump.conf option for this to turn on.

Hmm, thinking about this, another idea might be to simply let the fs
solve this by adding a high-level coredump.conf option to turn on
FS_COMPR_FL for the coredump. This should do the right thing on btrfs
(afaics at least), but of course would leave other file systems out. But
then again, we develop the OS for tomorrow, not for yesterday here...

But then again, maybe this stuff shouldn't be exclusive. Maybe a new
coredump.conf option Compress=(filesystem|file|no) or so? (and maybe
even Compress=auto, which does the right thing automatically, depending
if the fs supports compression) After all, doing both file-level and
filesystem-level compression makes little sense...

Lennart

-- 
Lennart Poettering, Red Hat