On 2017.05.15 at 16:24 +0200, Jakub Jelinek wrote: > On Mon, May 15, 2017 at 04:13:44PM +0200, Markus Trippelsdorf wrote: > > On 2017.05.15 at 14:02 +0000, Joseph Myers wrote: > > > The xz manpage warns against blindly using -9 (for which --best is a > > > deprecated alias) because of the implications for memory requirements for > > > decompressing. If there's a reason it's considered appropriate here, I > > > think it needs an explanatory comment. > > > > I think it is unacceptable, because it would increase memory usage when > > decompressing over 20x compared to bz2 (and over 100x while compressing). > > The memory using during compressing isn't that interesting as long as it > isn't prohibitive for sourceware or the machines RMs use. > For the decompression, I guess it matters what is actually the memory needed > for decompression the -9 gcc tarball, and compare that to minimal memory > requirements to compile (not bootstrap) the compiler using typical system > compilers. If compilation of gcc takes more memory than the decompression, > then it should be fine, why would anyone try to decompress gcc not to build > it afterwards?
Ok, it doesn't really matter. With gcc-7.1 tarball: size: 533084160 (uncompressed) -9: xz -d gcc.tar.xz 4.71user 0.26system 0:04.97elapsed 100%CPU (0avgtext+0avgdata 67804maxresident)k size: 60806928 -6 (default): xz -d gcc.tar.xz 4.88user 0.28system 0:05.17elapsed 99%CPU (0avgtext+0avgdata 10324maxresident)k size: 65059664 So -9 is actually just fine. -- Markus
