The custom_sched_clock hook is broken. The result from sched_clock needs to
be in nanoseconds, not in CPU cycles. The TSC is insufficient for this
purpose, because TSC is poorly defined in a virtual environment, and mostly
represents real world time instead of scheduled process time (which can be
interrupted without notice when a virtual machine is descheduled).
To make the scheduler consistent, we must expose a different nature of time,
that is scheduled time. So deprecate this custom_sched_clock hack and turn it
into a paravirt-op, as it should have been all along. This allows the tsc.c
code which converts cycles to nanoseconds to be shared by all paravirt-ops
backends.
It is unfortunate to add a new paravirt-op, but this is a very distinct
abstraction which is clearly different for all virtual machine
implementations, and it gets rid of an ugly indirect function which I
ashamedly admit I hacked in to try to get this to work earlier, and then even
got in the wrong units.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
VMI timer code. It works by taking over the local APIC clock when APIC is
configured, which requires a couple hooks into the APIC code. The backend
timer code could be commonized into the timer infrastructure, but there are
some pieces missing (stolen time, in particular), and the exact semantics of
when to do accounting for NO_IDLE need to be shared between different
hypervisors as well. So for now, VMI timer is a separate module.
[Adrian Bunk: cleanups]
Subject: VMI timer patches
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Create a paravirt.h header for all the critical operations which need to be
replaced with hypervisor calls, and include that instead of defining native
operations, when CONFIG_PARAVIRT.
This patch does the dumbest possible replacement of paravirtualized
instructions: calls through a "paravirt_ops" structure. Currently these are
function implementations of native hardware: hypervisors will override the ops
structure with their own variants.
All the pv-ops functions are declared "fastcall" so that a specific
register-based ABI is used, to make inlining assember easier.
And:
+From: Andy Whitcroft <apw@shadowen.org>
The paravirt ops introduce a 'weak' attribute onto memory_setup().
Code ordering leads to the following warnings on x86:
arch/i386/kernel/setup.c:651: warning: weak declaration of
`memory_setup' after first use results in unspecified behavior
Move memory_setup() to avoid this.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
