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commit 1a50ba2cb07d8bb2aa724062889deb9efd7ad9e9
Author: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
Date: Mon Nov 26 15:17:13 2012 +0100
qemu: Fix QMP Capabability Probing Failure
which attempted to make sure the QEMU process used for probing
ran as the right user id, caused serious performance regression
and unreliability in probing. The -daemonize switch in QEMU
guarantees that the monitor socket is present before the parent
process exits. This means libvirtd is guaranteed to be able to
connect immediately. By switching from -daemonize to the
virCommandDaemonize API libvirtd was no longer synchronized with
QEMU's startup process. The result was that the QEMU monitor
failed to open and went into its 200ms sleep loop. This happened
for all 25 binaries resulting in 5 seconds worth of sleeping
at libvirtd startup. In addition sometimes when libvirt connected,
QEMU would be partially initialized and crash causing total
failure to probe that binary.
This commit reverts the previous change, ensuring we do use the
-daemonize flag to QEMU. Startup delay is cut from 7 seconds
to 2 seconds on my machine, which is on a par with what it was
prior to the capabilities rewrite.
To deal with the fact that QEMU needs to be able to create the
pidfile, we switch pidfile location fron runDir to libDir, which
QEMU is guaranteed to be able to write to.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>