Instead of a hardcoded DEBUG log level, use the overall daemon log level specified in libvirtd.conf when opening a log stream with libxl. libxl is very verbose when DEBUG log level is set, resulting in huge log files that can potentially fill a disk. Control of libxl verbosity should be placed in the administrator's hands. Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt;

On Tue, Sep 15, 2015 at 09:26:23AM -0600, Jim Fehlig wrote: > Instead of a hardcoded DEBUG log level, use the overall > daemon log level specified in libvirtd.conf when opening > a log stream with libxl. libxl is very verbose when DEBUG > log level is set, resulting in huge log files that can > potentially fill a disk. Control of libxl verbosity should > be placed in the administrator's hands. > > Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; > --- > src/libxl/libxl_conf.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > ACK, this makes sense as default behaviour. As a future enhancement you might also consider supporting a config setting in /etc/libvirt/libxl.conf to explicitly control the libxl library logging behaviour independantly.

On Tue, Sep 15, 2015 at 10:57:50AM -0600, Jim Fehlig wrote: > Daniel P. Berrange wrote: > >> On Tue, Sep 15, 2015 at 09:26:23AM -0600, Jim Fehlig wrote: >> >> >>> Instead of a hardcoded DEBUG log level, use the overall >>> daemon log level specified in libvirtd.conf when opening >>> a log stream with libxl. libxl is very verbose when DEBUG >>> log level is set, resulting in huge log files that can >>> potentially fill a disk. Control of libxl verbosity should >>> be placed in the administrator's hands. >>> >>> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; >>> --- >>> src/libxl/libxl_conf.c | 18 +++++++++++++++++- >>> 1 file changed, 17 insertions(+), 1 deletion(-) >>> >>> >> ACK, this makes sense as default behaviour. As a future enhancement >> you might also consider supporting a config setting in /etc/libvirt/libxl.conf >> to explicitly control the libxl library logging behaviour independantly. >> >> > I had actually thought of adding it there first, but then took this > approach assuming it would be more receptive upstream :-). Personally, > I'm on the fence. I like the idea of a single knob to control log level > throughout the daemon, making it a bit easier on admins. On the other > hand, individual knobs are more friendly to those pouring through logs. > I can add a knob in libxl.conf if preferred. > After thinking about it some more, I could actually see value in create a dedicated virLogSource() instance, solely for libxl library messages. If we then created a virLogSourceGetPriority() method, you could query that to see if to turn on logging for the libxl library. That would ultimately allow you to turn on debug for just the libxl library if desired, eg static virLogSource virLogLibXL = { .name = "libxl.libxl_library", .... } LIBVIRT_LOG_FILTERS="1:libxl_library"

Regardless we should just merge your current patch right now.

On Sep 15, 2015, at 4:06 PM, John Ferlan <jferlan(a)redhat.com&gt; wrote: > On 09/15/2015 01:21 PM, Jim Fehlig wrote: > Daniel P. Berrange wrote: >>> On Tue, Sep 15, 2015 at 10:57:50AM -0600, Jim Fehlig wrote: >>> >>> Daniel P. Berrange wrote: >>> >>>> On Tue, Sep 15, 2015 at 09:26:23AM -0600, Jim Fehlig wrote: >>>> >>>> >>>>> Instead of a hardcoded DEBUG log level, use the overall >>>>> daemon log level specified in libvirtd.conf when opening >>>>> a log stream with libxl. libxl is very verbose when DEBUG >>>>> log level is set, resulting in huge log files that can >>>>> potentially fill a disk. Control of libxl verbosity should >>>>> be placed in the administrator's hands. >>>>> >>>>> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; >>>>> --- >>>>> src/libxl/libxl_conf.c | 18 +++++++++++++++++- >>>>> 1 file changed, 17 insertions(+), 1 deletion(-) >>>> ACK, this makes sense as default behaviour. As a future enhancement >>>> you might also consider supporting a config setting in /etc/libvirt/libxl.conf >>>> to explicitly control the libxl library logging behaviour independantly. >>> I had actually thought of adding it there first, but then took this >>> approach assuming it would be more receptive upstream :-). Personally, >>> I'm on the fence. I like the idea of a single knob to control log level >>> throughout the daemon, making it a bit easier on admins. On the other >>> hand, individual knobs are more friendly to those pouring through logs. >>> I can add a knob in libxl.conf if preferred. >> >> After thinking about it some more, I could actually see value in >> create a dedicated virLogSource() instance, solely for libxl >> library messages. If we then created a virLogSourceGetPriority() >> method, you could query that to see if to turn on logging for >> the libxl library. That would ultimately allow you to turn on >> debug for just the libxl library if desired, eg >> >> static virLogSource virLogLibXL = { >> .name = "libxl.libxl_library", >> .... >> } >> >> LIBVIRT_LOG_FILTERS="1:libxl_library" > > Ah, good idea. I'll look into it. > >> Regardless we should just merge your current patch right now. > > Thanks; done now. > > Regards, > Jim Looks like compilations on Fedora are 'unhappy':

Daniel P. Berrange wrote: > On Tue, Sep 15, 2015 at 10:57:50AM -0600, Jim Fehlig wrote: > >> Daniel P. Berrange wrote: >> >>> On Tue, Sep 15, 2015 at 09:26:23AM -0600, Jim Fehlig wrote: >>> >>> >>>> Instead of a hardcoded DEBUG log level, use the overall >>>> daemon log level specified in libvirtd.conf when opening >>>> a log stream with libxl. libxl is very verbose when DEBUG >>>> log level is set, resulting in huge log files that can >>>> potentially fill a disk. Control of libxl verbosity should >>>> be placed in the administrator's hands. >>>> >>>> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; >>>> --- >>>> src/libxl/libxl_conf.c | 18 +++++++++++++++++- >>>> 1 file changed, 17 insertions(+), 1 deletion(-) >>>> >>>> >>> ACK, this makes sense as default behaviour. As a future enhancement >>> you might also consider supporting a config setting in /etc/libvirt/libxl.conf >>> to explicitly control the libxl library logging behaviour independantly. >>> >>> >> I had actually thought of adding it there first, but then took this >> approach assuming it would be more receptive upstream :-). Personally, >> I'm on the fence. I like the idea of a single knob to control log level >> throughout the daemon, making it a bit easier on admins. On the other >> hand, individual knobs are more friendly to those pouring through logs. >> I can add a knob in libxl.conf if preferred. >> > > After thinking about it some more, I could actually see value in > create a dedicated virLogSource() instance, solely for libxl > library messages. If we then created a virLogSourceGetPriority() > method, you could query that to see if to turn on logging for > the libxl library. That would ultimately allow you to turn on > debug for just the libxl library if desired, eg > > static virLogSource virLogLibXL = { > .name = "libxl.libxl_library", > .... > } > > LIBVIRT_LOG_FILTERS="1:libxl_library" > Ah, good idea. I'll look into it.

On Wed, Nov 11, 2015 at 04:57:59PM +0100, Marek Marczykowski-Górecki wrote: > On Tue, Sep 15, 2015 at 11:21:00AM -0600, Jim Fehlig wrote: > > Daniel P. Berrange wrote: > > > On Tue, Sep 15, 2015 at 10:57:50AM -0600, Jim Fehlig wrote: > > > > > >> Daniel P. Berrange wrote: > > >> > > >>> On Tue, Sep 15, 2015 at 09:26:23AM -0600, Jim Fehlig wrote: > > >>> > > >>> > > >>>> Instead of a hardcoded DEBUG log level, use the overall > > >>>> daemon log level specified in libvirtd.conf when opening > > >>>> a log stream with libxl. libxl is very verbose when DEBUG > > >>>> log level is set, resulting in huge log files that can > > >>>> potentially fill a disk. Control of libxl verbosity should > > >>>> be placed in the administrator's hands. > > >>>> > > >>>> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; > > >>>> --- > > >>>> src/libxl/libxl_conf.c | 18 +++++++++++++++++- > > >>>> 1 file changed, 17 insertions(+), 1 deletion(-) > > >>>> > > >>>> > > >>> ACK, this makes sense as default behaviour. As a future enhancement > > >>> you might also consider supporting a config setting in /etc/libvirt/libxl.conf > > >>> to explicitly control the libxl library logging behaviour independantly. > > >>> > > >>> > > >> I had actually thought of adding it there first, but then took this > > >> approach assuming it would be more receptive upstream :-). Personally, > > >> I'm on the fence. I like the idea of a single knob to control log level > > >> throughout the daemon, making it a bit easier on admins. On the other > > >> hand, individual knobs are more friendly to those pouring through logs. > > >> I can add a knob in libxl.conf if preferred. > > >> > > > > > > After thinking about it some more, I could actually see value in > > > create a dedicated virLogSource() instance, solely for libxl > > > library messages. If we then created a virLogSourceGetPriority() > > > method, you could query that to see if to turn on logging for > > > the libxl library. That would ultimately allow you to turn on > > > debug for just the libxl library if desired, eg > > > > > > static virLogSource virLogLibXL = { > > > .name = "libxl.libxl_library", > > > .... > > > } > > > > > > LIBVIRT_LOG_FILTERS="1:libxl_library" > > > > > > > Ah, good idea. I'll look into it. > > Is it done anywhere? If not, how can I help? > > This the above change (setting libxl log level to libvirtd global one), > makes almost impossible to get libxl debug, because the rest of libvirtd > trashes the logs (hundreds virEvent* and virObject* messages, at > "info"(!) level). Presumably that's because you are using LIBVIRT_DEBUG=1 or setting log_debug=1 in /etc/libvirt/libvirtd.log. That is generally discouraged because it turns on all logging, which is essentially unusably verbose. It is also better to use more specific log settings, eg when I debug the QEMU driver I usually use log_filters="1:qemu 1:security 3:event 3:object 1:util" log_outputs="1:file:/var/log/libvirt/libvirtd.log" This generates log messages from every source file in qemu and security directories, and also log messages from every file in the util/ directory *except* for event & object files. So it is much more managable to read.

The log filter strings just do a wildcard match against the VIR_LOG_INIT("...."); lines in each source file, so you can make things more or less specific as you desire. Regards, Daniel