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RE: [Xen-devel] [PATCH] time-xen : Reset monotonic time when sync up tim

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH] time-xen : Reset monotonic time when sync up time from dom0 to domU
From: "Du, Hang" <hdu@xxxxxxxxxxxx>
Date: Tue, 12 Oct 2010 20:24:35 -0700
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Cc: "Liu, Saipu" <saliu@xxxxxxxxxxxx>, "Yi, Shunli" <syi@xxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] [PATCH] time-xen : Reset monotonic time when sync up time from dom0 to domU

Sorry for my brief description in previous mail and missing 
is_initial_xendomain check. The kernel I submit this patch is 
linux-2.6.18-xen-3.4.2, I submit the patch again with in_initial-xendomain 

In this patch, we support the backward time changing sync to all domUs which 
configured to use "dependent wall clock".
Currently, without the backward time syncing, when we change the time backward 
in Dom0, the time in DomU would be froze. 
And this cause some commands hang and don't executed until the time catch up 
with the domU time.
For example:
"rpm -q kernel-xen"
"sleep 1"
Monotonic time should be reset when sync up time from dom0 to domU to support 
domU backward time syncing.

diff -urN a/arch/i386/kernel/time-xen.c   b/arch/i386/kernel/time-xen.c   

--- a/arch/i386/kernel/time-xen.c   2010-10-11 10:41:06.000000000 +0800
+++ b/arch/i386/kernel/time-xen.c   2010-10-11 10:43:32.000000000 +0800
@@ -715,6 +715,8 @@
    if (shadow_tv_version != HYPERVISOR_shared_info->wc_version) {
+        if (!is_initial_xendomain() && !independent_wallclock)
+            monotonic_reset();
        schedule_clock_was_set_work = 1;

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Attachment: time-xen.patch
Description: time-xen.patch

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