On Mon, Apr 30, 2018 at 11:05:48AM -0400, John Ferlan wrote: > > > On 04/23/2018 08:28 AM, Daniel P. Berrangé wrote: > > Rather than specialcasing handling of the '*' character, use fnmatch() > > to get normal shell wildcard syntax, as described in 'man glob(7)'. > > > > To get an indication of the performance impact of using globs instead > > of plain string matches, a test program was written. The list of all > > 260 log categories was extracted from the source. Then a typical log > > filters setup was picked by creating an array of the strings "qemu", > > "security", "util", "cgroup", "event", "object". Every filter string > > was matched against every log category. Timing information showed that > > using strstr() this took 8 microseconds, while fnmatch() took 114 > > microseconds. > > > > IOW, fnmatch is 14 times slower than our existing strstr check. These > > numbers show a worst case scenario that wil never be hit, because it > > s/wil/will > > > is rare that every log category would have data output. The log category > > matches are cached, so each category is only checked once no matter how > > many log statements are emitted. IOW despite being slower, this will > > be lost in the noise and have no consequence on real world logging > > performance. > > > > Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx> > > --- > > src/util/virlog.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > Reviewed-by: John Ferlan <jferlan@xxxxxxxxxx> > > John > > BTW: So whether this is available "everywhere" is a bit of an unknown to > me - as in strstr would seemingly work on every arch, but fnmatch has > this linux-ism wildcard thing going on which leaves a slight bit of > doubt in my mind... NB, we rely on gnulib to provide us fnmatch on all platforms 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 :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
