* [PATCH] docs: Update xen-tscmode.pod.7 to reflect default TSC mode changes
@ 2017-03-29 14:49 Boris Ostrovsky
2017-03-30 11:24 ` Wei Liu
0 siblings, 1 reply; 2+ messages in thread
From: Boris Ostrovsky @ 2017-03-29 14:49 UTC (permalink / raw)
To: xen-devel
Cc: olaf, wei.liu2, andrew.cooper3, ian.jackson, jbeulich, Boris Ostrovsky
A number of changes have been made to how we determine whether TSC
is emulated (e.g. commit 4fc380ac0077 ("x86/time: don't use virtual TSC
if host and guest frequencies are equal")).
Update the man page to reflect those changes
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Suggested-by: Olaf Hering <olaf@aepfle.de>
---
docs/man/xen-tscmode.pod.7 | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/docs/man/xen-tscmode.pod.7 b/docs/man/xen-tscmode.pod.7
index 0da57e5..0f93453 100644
--- a/docs/man/xen-tscmode.pod.7
+++ b/docs/man/xen-tscmode.pod.7
@@ -203,12 +203,12 @@ The default mode (tsc_mode==0) checks TSC-safeness of the underlying
hardware on which the virtual machine is launched. If it is
TSC-safe, rdtsc will execute at hardware speed; if it is not, rdtsc
will be emulated. Once a virtual machine is save/restored or migrated,
-however, there are two possibilities: For a paravirtualized (PV) domain,
-TSC will always be emulated. For a fully-virtualized (HVM) domain,
-TSC remains native IF the source physical machine and target physical machine
-have the same TSC frequency; else TSC is emulated. Note that, though
-emulated, the "apparent" TSC frequency will be the TSC frequency
-of the initial physical machine, even after migration.
+however, there are two possibilities: TSC remains native IF the source
+physical machine and target physical machine have the same TSC frequency
+(or, for HVM/PVH guests, if TSC scaling support is available); else TSC
+is emulated. Note that, though emulated, the "apparent" TSC frequency
+will be the TSC frequency of the initial physical machine, even after
+migration.
For environments where both TSC-safeness AND highest performance
even across migration is a requirement, application code can be specially
--
2.7.4
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] docs: Update xen-tscmode.pod.7 to reflect default TSC mode changes
2017-03-29 14:49 [PATCH] docs: Update xen-tscmode.pod.7 to reflect default TSC mode changes Boris Ostrovsky
@ 2017-03-30 11:24 ` Wei Liu
0 siblings, 0 replies; 2+ messages in thread
From: Wei Liu @ 2017-03-30 11:24 UTC (permalink / raw)
To: Boris Ostrovsky
Cc: olaf, wei.liu2, andrew.cooper3, ian.jackson, xen-devel, jbeulich
On Wed, Mar 29, 2017 at 10:49:34AM -0400, Boris Ostrovsky wrote:
> A number of changes have been made to how we determine whether TSC
> is emulated (e.g. commit 4fc380ac0077 ("x86/time: don't use virtual TSC
> if host and guest frequencies are equal")).
>
> Update the man page to reflect those changes
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Suggested-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wei.liu2@citrix.com>
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https://lists.xen.org/xen-devel
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2017-03-29 14:49 [PATCH] docs: Update xen-tscmode.pod.7 to reflect default TSC mode changes Boris Ostrovsky
2017-03-30 11:24 ` Wei Liu
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