Hello, I cannot find a way to retrieve PIDs of QEMU instances from libvirt domains' IDs (I'm using libvirt C API). I recognize it sounds like a bad idea doing so (and I know PIDs are explicitly made not available, as I gathered from the source code and on your IRC channel) but I need that to use the perf_event_open syscall in order to gather statistics on my QEMU/KVM guests. I also know libvirt now supports some perf events but only a few and I need more. I could submit patches to add them and I will definitely consider that but in the meantime... What would be the best way to get those PIDs? I tried using the XML file but PID is hidden in there too. I took a look at QEMU Machine Protocol. Now I'm going to walk /proc and match on guests names but it is not that elegant. Any ideas?

Thanks, Thibaut S. _______________________________________________ libvirt-users mailing list libvirt-users(a)redhat.com https://www.redhat.com/mailman/listinfo/libvirt-users

On Tue, Mar 21, 2017 at 12:06:25 +0100, Martin Kletzander wrote: > On Mon, Mar 20, 2017 at 02:11:21PM +0100, Thibaut SAUTEREAU wrote: > > Hello, > > > > I cannot find a way to retrieve PIDs of QEMU instances from libvirt domains' > > IDs (I'm using libvirt C API). I recognize it sounds like a bad idea doing so > > (and I know PIDs are explicitly made not available, as I gathered from the > > source code and on your IRC channel) but I need that to use the perf_event_open > > syscall in order to gather statistics on my QEMU/KVM guests. I also know > > libvirt now supports some perf events but only a few and I need more. I could > > submit patches to add them and I will definitely consider that but in the > > meantime... Looks like you are looking for: http://libvirt.org/formatdomain.html#elementsPerf and http://libvirt.org/html/libvirt-libvirt-domain.html#virDomainGetPerfEvents > > > > What would be the best way to get those PIDs? I tried using the XML file but > > PID is hidden in there too. I took a look at QEMU Machine Protocol. Now I'm > > going to walk /proc and match on guests names but it is not that elegant. > > Any ideas? Just to re-iterate. We hide it because users should not fiddle with the VMs behind our backs. > > > > `ps aux | grep $UUID | grep -v grep` ?? This will obviously work, but we won't give you an elegant way since we don't want you to know the pid.