Hi, On 25 May 2015 at 16:58, Julian Andres Klode <[email protected]> wrote: > Those seem to be uncached or on compressed indices, and thus not > relevant for this bug.
fair enough. Still, even with cached and uncompressed indices a single apt-cache show takes about 1.6 seconds on jessie and about 1.2 seconds on wheezy. >> How about using the O_CLOEXEC flag when opening files? > > We do, AFAIK. Wouldn't that render the fcntl calls superfluous? Also I can't find any relevant occurences of O_CLOEXEC in the codebase (apart from one in pkgDPkgPM::StartPtyMagic). > I'm wondering a bit because show only does about 38 fcntl() calls for > me, it does not seem to ForkExec() here at all (and I don't know why > it should do that at all). Interesting. You haven't set your Apt::ARCHITECTURES to a single arch by any chance, have you? > I just tested the closing call, and it took about 4 ms (or 10-12 in > jessie) for the program to start up, call fcntl() on the 65533 file > descriptors, and exit. I cannot believe that this is the major > performance difference you are experiencing between wheezy and jessie. > > Anyway, I fixed this in > http://anonscm.debian.org/cgit/apt/apt.git/commit/?id=870a2b6d683e58c0584bbd3614a76cf25a055928 > to use /proc/self/fd where available. This brings us down to 0.72 ms > in my optimal test case. While this version is still a bit slower than the one in wheezy, it is significantly faster than the one currently in jessie: Most recent git version: ~ # time apt-cache show mg > /dev/null apt-cache policy mg > /dev/null 0.01s user 0.00s system 51% cpu 0.015 total apt 1.0.9.8 (jessie): ~ # time apt-cache show mg > /dev/null apt-cache show mg > /dev/null 0.01s user 0.04s system 92% cpu 0.061 total On the docker instance on my laptop with uncompressed indices I'm down from 2.2s to 1.4s. All in all a noticeable improvement. Thank you for the quick response; next time I'll make sure to start testing in time for the stable release. Best, Sebastian -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
