| From: |
| Glauber Costa <glommer@redhat.com> |
| To: |
| kvm@vger.kernel.org |
| Subject: |
| [PATCH 0/2] Automatically grab wallclock time updates from hypervisor |
| Date: |
| Tue, 1 Sep 2009 07:50:46 -0400 |
| Message-ID: |
| <1251805848-17451-1-git-send-email-glommer@redhat.com> |
| Cc: |
| linux-kernel@vger.kernel.org, avi@redhat.com |
| Archive‑link: | |
Article |
Hi folks,
In this proposed patch, I am introducing a worker fired by kvmclock that updates
guest wallclock periodically to reflect changes in the host's wallclock. With this
patch, a large pool of VMs will no longer have to run NTP in all of its guests.
The worker does that at a configurable interval, with a minimum granularity of 1
second. So, although not exactly cheap, the msr write needed to get an updated
wallclock value won't pose a heavy burden on the system.
It is also possible to disable it completely if this behaviour is undesired for
a specific scenario.
diffstat follows:
arch/x86/include/asm/kvm_para.h | 6 +++
arch/x86/kernel/kvmclock.c | 77 ++++++++++++++++++++++++++++++++++-----
kernel/sysctl.c | 13 +++++++
3 files changed, 87 insertions(+), 9 deletions(-)
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