Re: [libvirt] [PATCH RFC] qemu: caps: invalidate kvm capable qemu binaries on every restart
On Fri, Dec 28, 2018 at 15:06:36 +0300, Nikolay Shirokovskiy wrote:
If qemu binary exposes kvm then caps depends heavily on host state.
We are already check explicitly some host features - kernel version,
microcode version, nested flag state. This won't nesserily help if somebody
change CPU on host. Let's instead invalidate such caps on every daemon
Well, that isn't something that happens regularly. Also usually in that
case the OS is reinstalled as well.
restart. This makes kernel version and microcode version check
excessive but nested flag is still need to be checked.
Cache invalidating on restart is archived by keeping list of
binaries that whose caps cache was validated at least once.
If binary in not yet validated and supports kvm then we need to
invalidate it's caps cache.
Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy(a)virtuozzo.com>
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If the patch will be accepted then I'll send a patch which removes mentioned
excessive checks also.
Well, the whole point of this is to shorten the startup time of the
daemon if nothing changed.
In some cases I would agree that we can do it on a host restart, but
dropping caches on daemon restart is too excessive. Also in that case
all caching on disk can be removed.
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