Re: [libvirt] [PATCH v2 3/4] log: support logging using shell wildcard syntax

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

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(a)redhat.com&gt; --- src/util/virlog.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)