On Wed, Jul 03, 2019 at 09:19:17AM +0200, Michal Privoznik wrote:
If the limit for max opened files is way bigger than the default (1024), say 3 orders bigger then spawning a child through virCommand can be expensive because we iterate over ALL FDs within the limit and close them. There's no need to that since we can learn the list of opened FDs from /proc/self/fd/.
Yeah I've seen this in docker containers in particular where the nfiles limit is something like 2 million. Hopefully Linux will finally get something equiv to BSD's closefrom() syscall we can use in the future: https://lwn.net/Articles/593778/ meanwhile relying on /proc is reasonable I guess. The extra syscalls to read the dir should be balanced by fewer close syscalls quite easily. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|