QEMU_CLOCK_HOST is based on the system time which may jump backward in
case the admin or NTP adjusts it. RTC emulations and other device models
can suffer in this case as timers will stall for the period the clock
was tuned back.
This adds a detection mechanism that checks on every host clock readout
if the new time is before the last result. If that is the case a
notifier list is informed. Device models interested in this event can
register a notifier with the clock.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
It was a half conversion. Finish it.
enabled can only get values of 0, 1 or 2, was declared as an int but
sent as an unint8_t, change its type.
Signed-off-by: Juan Quintela <quintela@redhat.com>
It is purely for icount-based virtual timers. And now that we got the
code right, rename the function to clarify the intended scope.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
The previous patch however is not enough, because if the virtual CPU
goes to sleep waiting for a future timer interrupt to wake it up, qemu
deadlocks. The timer interrupt never comes because time is driven by
icount, but the vCPU doesn't run any insns.
You could say that VCPUs should never go to sleep in icount
mode if there is a pending vm_clock timer; rather time should
just warp to the next vm_clock event with no sleep ever taking place.
Even better, you can sleep for some time related to the
time left until the next event, to avoid that the warps are too visible
externally; for example, you could be sending network packets continously
instead of every 100ms.
This is what this patch implements. qemu_clock_warp is called: 1)
whenever a vm_clock timer is adjusted, to ensure the warp_timer is
synchronized; 2) at strategic points in the CPU thread, to make sure
the insn counter is synchronized before the CPU starts running.
In any case, the warp_timer is disabled while the CPU is running,
because the insn counter will then be making progress on its own.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
These patches are already not doing a great service to out-of-tree
modifications to QEMU. However, at least we can warn them by getting
rid of the old confusing functions, or otherwise causing compilation
errors. This patch removes qemu_get_clock; the previous one changed
qemu_new_timer's signature.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This enables rt_clock timers to use nanosecond resolution, just by
using the _ns functions; there is really no reason to forbid that.
Migrated timers are all using vm_clock (of course; but I checked that
anyway) so the timers in the savevm files are already in nanosecond
resolution. So this patch makes no change to the migration format.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The code doesn't make much sense right now, but it will as
soon as timers will be able to scale their resolution arbitrarily.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move timer init functions to a new file, qemu-timer-common.c. Make other
critical timer functions inlined to preserve performance in
qemu-timer.c, also move muldiv64() (used by the inline functions)
to qemu-timer.h.
Adjust block/raw-posix.c and simpletrace.c to use get_clock() directly.
Remove a similar/duplicate definition in qemu-tool.c.
Adjust hw/omap_clk.c to include qemu-timer.h because muldiv64() is used
there.
After this change, tracing can be used also for user code and
simpletrace on Win32.
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Acked-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
There's a header file inclusion ordering problem between cpu-all.h
and qemu-timer.h, such that cpu_get_real_ticks is not defined when
we attempt to use it in profile_getclock.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
PowerPC CPUs have had two ways to read the time base for quite some time now.
They provide it using the mfspr instruction or - if a special bit is set in
that opcode - using mftb. For timekeeping we're currently using mftb.
While trying to get Qemu up and running on an e500v2 system, I stumbled over
the CPU not supporting mftbu. It just throws an illegal instruction trap.
So let's read the SPR values instead. All PPC CPUs should support them anyways.
I tested this patch on an e500v2 system where it makes qemu work and on my 970MP
system with 32-bit user space where everything still works with this patch
applied.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: malc <av1474@comtv.ru>
Arrange various declarations so that also non-CPU code can access
them, adjust users.
Move CPU specific code to cpus.c.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Some places use get_clock directly because they want to access the
rt_clock with nanosecond precision. Add a function to do exactly that
instead of using internal interfaces.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Despite its name QEMU_CLOCK_REALTIME is (normally) not using
CLOCK_REALTIME / the host system time as base. In order to allow also
non-trivial RTC emulations (MC146818) to follow the host time instead of
the virtual guest time, introduce the new clock type QEMU_CLOCK_HOST. It
is unconditionally based on CLOCK_REALTIME, thus will follow system time
changes of the host.
The only limitation of its current implementation is that pending
host_clock timers may not fire early if the host time is pushed forward
beyond their expiry. So far no urgent need to overcome this limitation
was identified, so it's left as simple as it is (expiry on next alarm
timer tick).
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
ticks_per_sec is a constant. There's no need to store it as a variable as it
never changes since our time is based on units.
Convert get_ticks_per_sec() to a static inline and move the constant into
qemu-timer.h. Remove all references to QEMU_TIMER_BASE so that we consistently
use this interface.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch introduces dynamic timer intervals: we slow down the refresh
rate when there in no much activity but we get back to a fast refresh
rate when the activity resume.
Please note that qemu_timer_expired is not an inline function any more
because I needed to call it from vnc.c however I don't think this change
should have any serious consequence.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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