Op 25 jun. 2014, om 10:59 heeft Lennart Poettering <[email protected]> het volgende geschreven:
> On Wed, 25.06.14 07:28, Zbigniew Jędrzejewski-Szmek ([email protected]) 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... The way btrfs currently does compression is to compress every (iirc 4k) block separately. Compressing the whole file at once will give a much bigger saving, especially when using xz. So btrfs/lzo will give you ~50% compression ratio vs the 5% mentioned above, a huge difference. I don't know how reiser4 or zfs tackle this. regards, Koen _______________________________________________ systemd-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/systemd-devel
