* Avi Kivity <avi@xxxxxxxxxx> wrote: > > Lets look at the ${HOME}/.qemu/qmp/ enumeration method suggested by > > Anthony. There's numerous ways that this can break: > > I don't like it either. We have libvirt for enumerating guests. Which has pretty much the same problems to the ${HOME}/.qemu/qmp/ solution, obviously. > > - Those special files can get corrupted, mis-setup, get out of sync, or can > > be hard to discover. > > > > - The ${HOME}/.qemu/qmp/ solution suggested by Anthony has a very obvious > > design flaw: it is per user. When i'm root i'd like to query _all_ current > > guest images, not just the ones started by root. A system might not even > > have a notion of '${HOME}'. > > > > - Apps might start KVM vcpu instances without adhering to the > > ${HOME}/.qemu/qmp/ access method. > > - it doesn't work with nfs. So out of a list of 4 disadvantages your reply is that you agree with 3? > > - There is no guarantee for the Qemu process to reply to a request - while > > the kernel can always guarantee an enumeration result. I dont want 'perf > > kvm' to hang or misbehave just because Qemu has hung. > > If qemu doesn't reply, your guest is dead anyway. Erm, but i'm talking about a dead tool here. There's a world of a difference between 'kvm top' not showing new entries (because the guest is dead), and 'perf kvm top' hanging due to Qemu hanging. So it's essentially 4 our of 4. Yet your reply isnt "Ingo you are right" but "hey, too bad" ? > > Really, for such reasons user-space is pretty poor at doing system-wide > > enumeration and resource management. Microkernels lost for a reason. > > Take a look at your desktop, userspace is doing all of that everywhere, from > enumerating users and groups, to deciding how your disks are named. The > kernel only provides the bare facilities. We dont do that for robust system instrumentation, for heaven's sake! By your argument it would be perfectly fine to implement /proc purely via user-space, correct? > > You are committing several grave design mistakes here. > > I am committing on the shoulders of giants. Really, this is getting outright ridiculous. You agree with me that Anothony suggested a technically inferior solution, yet you even seem to be proud of it and are joking about it? And _you_ are complaining about lkml-style hard-talk discussions? Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html