On Fri, Feb 02, 2018 at 06:05:56PM +0100, Peter Krempa wrote:
On Fri, Feb 02, 2018 at 15:27:22 +0100, Martin Kletzander wrote:Since one of the things in capabilities (info from resctrl updated with data about caches) can be change on the system by remounting the /sys/fs/resctrl with different options, the capabilities need to be refreshed. There is a better fix in the works, but it's going to be way bigger than this (hence the XXX note there), so for the time being let's workaround this. And in order not to slow down the domain starting, only get the capabilities if there are any cachetunes. Relates-to: https://bugzilla.redhat.com/show_bug.cgi?id=1540780 Signed-off-by: Martin Kletzander <mkletzan@xxxxxxxxxx> --- src/qemu/qemu_process.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 5a364730c8c1..2ab242b7634d 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -2514,9 +2514,15 @@ qemuProcessResctrlCreate(virQEMUDriverPtr driver, { int ret = -1; size_t i = 0; - virCapsPtr caps = virQEMUDriverGetCapabilities(driver, false); + virCapsPtr caps = NULL; qemuDomainObjPrivatePtr priv = vm->privateData; + if (!vm->def->ncachetunes) + return 0; + + /* Force capability refresh since resctrl info can change + * XXX: move cache info into virresctrl so caps are not needed */ + caps = virQEMUDriverGetCapabilities(driver, true);I hope that your upcoming fix will also deal with the hugepage and NUMa data which is more often used than this.
Actually, it will just deal with resctrl info being as consistent as possible. I mean you can always remount the directory between libvirtd reading the two files, there will always be a window of opportunity. The fix I have in mind (and code) is just going to make rid of the capability usage from the driver in resctrl-related code. Do you have any pointers to the numa and hugepage faults that we ought to fix? Maybe it can be dealt with the same way.
My feelings towards doing this are slightly mixed, but ACK
Thanks, pinky swear that I'll remove it in near future ;)
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