These let a user anticipate the deadline of a timer, atomically with
other sites that call the function. This helps avoiding complicated
lock hierarchies.
Reviewed-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
After disabling the QemuClock, we should make sure that no QemuTimers
are still in flight. To implement that with light overhead, we resort
to QemuEvent. The caller of disabling will wait on QemuEvent of each
timerlist.
Note, qemu_clock_enable(foo,false) can _not_ be called from timer's cb.
Also, the callers of qemu_clock_enable() should be protected by the BQL.
Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We can deduce the result from expire_time, by making it always -1 if
the timer is not in the active_timers list. We need to check against
negative times passed to timer_mod_ns; clamping them to zero is not
a problem because the only clock that has a zero value at VM startup
is QEMU_CLOCK_VIRTUAL, and it is monotonic so it cannot be non-zero.
QEMU_CLOCK_HOST, instead, is not monotonic but it cannot go to negative
values unless the host time is seriously screwed up and points to
the 1960s.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Introduce QEMUTimerList->active_timers_lock to protect the linked list
of active timers. This allows qemu_timer_mod_ns() to be called from any
thread.
Note that vm_clock is not thread-safe and its use of
qemu_clock_has_timers() works fine today but is also not thread-safe.
The purpose of this patch is to eventually let device models set or
cancel timers from a vcpu thread without holding the global mutex.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
host_alarm_handler() is invoked from the signal processing thread
(currently the iothread). Previously we did processing in a real signal
handler with signalfd and therefore needed signal-safe timer code.
Today host_alarm_handler() just marks the alarm timer as expired/pending
and notifies the main loop using qemu_notify_event().
Therefore these outdated comments about signal safety can be dropped.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Remove the legacy interface from include/qemu/timers.h.
Ensure struct QEMUClock is not exposed at all.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Now we have timerlistgroups implemented and main_loop_tlg, we
no longer need the concept of a default timer list associated
with each clock. Remove it and simplify initialisation of
clocks and timer lists.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Rearrange timer.h so it is in order by function type.
Make legacy functions call non-legacy functions rather than vice-versa.
Convert cpus.c to use new API.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Remove qemu_clock_deadline and qemu_timerlist_deadline now we are using
the ns functions throughout.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Remove alarm timers from qemu-timers.c now we use g_poll / ppoll
instead.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Notify all timerlists derived from vm_clock in icount warp
calculations.
When calculating timer delay based on vm_clock deadline, use
all timerlists.
For compatibility, maintain an apparent bug where when using
icount, if no vm_clock timer was set, qemu_clock_deadline
would return INT32_MAX and always set an icount clock expiry
about 2 seconds ahead.
NB: thread safety - when different timerlists sit on different
threads, this will need some locking.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
On qemu_mod_timer_ns, ensure qemu_notify or aio_notify is called to
end the appropriate poll(), irrespective of use_icount value.
On qemu_clock_enable, ensure qemu_notify or aio_notify is called for
all QEMUTimerLists attached to the QEMUClock.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Add a notify pointer to QEMUTimerList so it knows what to notify
on a timer change.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Add QEMUTimerListGroup and helper functions, to represent
a QEMUTimerList associated with each clock. Add a default
QEMUTimerListGroup representing the default timer lists
which are not associated with any other object (e.g.
an AioContext as added by future patches).
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Split QEMUClock into QEMUClock and QEMUTimerList so that we can
have more than one QEMUTimerList associated with the same clock.
Introduce a main_loop_timerlist concept and make existing
qemu_clock_* calls that actually should operate on a QEMUTimerList
call the relevant QEMUTimerList implementations, using the clock's
default timerlist. This vastly reduces the invasiveness of this
change and means the API stays constant for existing users.
Introduce a list of QEMUTimerLists associated with each clock
so that reenabling the clock can cause all the notifiers
to be called. Note the code to do the notifications is added
in a later patch.
Switch QEMUClockType to an enum. Remove global variables vm_clock,
host_clock and rt_clock and add compatibility defines. Do not
fix qemu_next_alarm_deadline as it's going to be deleted.
Add qemu_clock_use_for_deadline to indicate whether a particular
clock should be used for deadline calculations. When use_icount
is true, vm_clock should not be used for deadline calculations
as it does not contain a nanosecond count. Instead, icount
timeouts come from the execution thread doing aio_notify or
qemu_notify as appropriate. This function is used in the next
patch.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Make qemu_run_timers and qemu_run_all_timers return progress
so that aio_poll etc. can determine whether a timer has been
run.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Where supported, called prctl(PR_SET_TIMERSLACK, 1, ...) to
set one nanosecond timer slack to increase precision of timer
calls.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Add qemu_poll_ns which works like g_poll but takes a nanosecond
timeout.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Make treatment of disabled clocks consistent in deadline calculation
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Add utility functions to qemu-timer.c for nanosecond timing.
Add qemu_clock_deadline_ns to calculate deadlines to
nanosecond accuracy.
Add utility function qemu_soonest_timeout to calculate soonest deadline.
Add qemu_timeout_ns_to_ms to convert a timeout in nanoseconds back to
milliseconds for when ppoll is not used.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Rename qemu_new_clock to qemu_clock_new.
Expose clock types.
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Rename four functions in preparation for new API.
Rename qemu_timer_expired to timer_expired
Rename qemu_timer_expire_time_ns to timer_expire_time_ns
Rename qemu_timer_pending to timer_pending
Rename qemu_timer_expired_ns to timer_expired_ns
Signed-off-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
These are needed for any of the Win32 alarm timer implementations.
They are not tied to mmtimer exclusively.
Jacob tested this patch with both mmtimer and Win32 timers.
Cc: qemu-stable@nongnu.org
Tested-by: Jacob Kroon <jacob.kroon@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
A compiler warning is caused by the unused local function reinit_timers
on non-POSIX hosts. Include that function only for POSIX hosts.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Timers are not inherited by the child of a fork(2), so just use
pthread_atfork to reinstate them after daemonize.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Older glibc (RHEL 5.x, Debian 5.x) does not have the _sigev_un._tid
member in its structure definition, while the accompanying kernel
headers do define SIGEV_THREAD_ID. We need configure to check for
both before using it.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
ptimer_head is an invariant pointer to clock->active_timers.
Remove it, and just reference clock->active_timers directly.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
QEMU will hang when fed the following command-line
qemu-system-mips -kernel vmlinux-2.6.32-5-4kc-malta -append "console=ttyS0" -nographic -net none
The -net none is important otherwise it seems some events are generated
causing the things to work. When it doesn't work, the guest hangs when
measuring the CPU frequency, after the following line:
[ 0.000000] NR_IRQS:256
Pressing a key on the serial port unblocks it, hinting that the problem
is due to the recent elimination of the 1 second timeout in the main
loop.
The problem is that because init_timer_alarm sets the timer's pending
flag to true, the alarm timer is never armed until after the first time
through the main loop. Thus the bug started when QEMU started testing
the pending flag in qemu_mod_timer (commit 1828be3, more alarm timer
cleanup, 2010-03-10).
But actually, it isn't true at all that a timer is pending when the
alarm timer is created, and the real bug has been latent forever: the
fix is to remove the bogus setting of pending flag.
Reported-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
qemu_rearm_alarm_timer partially duplicates the code in
qemu_next_alarm_deadline to figure out if it needs to rearm the timer.
If it calls qemu_next_alarm_deadline, it always rearms the timer even if
the next deadline is INT64_MAX.
This patch simplifies the behavior of qemu_rearm_alarm_timer and removes
the duplicated code, always calling qemu_next_alarm_deadline and only
rearming the timer if the deadline is less than INT64_MAX.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Tested-by: Andreas Färber <andreas.faerber@web.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
For command line options which permit '?' meaning 'please list the
permitted values', add support for 'help' as a synonym, by abstracting
the check out into a helper function.
This change means that in some cases where we were being lazy in
our string parsing, "?junk" will now be rejected as an invalid option
rather than being (undocumentedly) treated the same way as "?".
Update the documentation to use 'help' rather than '?', since '?'
is a shell metacharacter and thus prone to fail confusingly if there
is a single character filename in the current working directory and
the '?' has not been escaped. It's therefore better to steer users
towards 'help', though '?' is retained for backwards compatibility.
We do not, however, update the output of the system emulator's -help
(or any documentation autogenerated from the qemu-options.hx which
is the source of the -help text) because libvirt parses our -help
output and will break. At a later date when QEMU provides a better
interface so libvirt can avoid having to do this, we can update the
-help text too.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Function timeSetEvent returns 0 when it fails, but it does not set
an error code which can be retrieved by GetLastError.
Therefore calling GetLastError is useless.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
sys/param.h is needed for __FreeBSD_version.
Pointed out by Juergen, thanks.
Signed-off-by: Andreas Faerber <andreas.faerber@web.de>
Cc: Juergen Lock <nox@jelal.kn-bremen.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
timeSetEvent only accepts delays in the range which is returned by
timeGetDevCaps.
The lower limit is typically 1 (= 1 ms), so the constant value of 1
in the old code usually worked.
The upper limit can be as low as 10000 ms, so the latest changes in
QEMU's timer handling which introduced timeout values above that limit
could result in failures of timeSetEvent when the timer was re-armed.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Remove all holes which were found by pahole on Linux x86_64
(and replace "struct QEMUTimer" by "QEMUTimer").
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Some time ago, the last time which did not have dynticks was removed,
so now all timers have dynticks.
I also removed a misleading error message for the dynticks timer.
If timer_create fails, there is already an error message, and
QEMU will use the unix timer which also provides dynamic ticks,
therefore dynamic ticks are not disabled.
v2:
Remove two if statements because they were always true
(thanks to Paolo Bonzini for this correction).
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
This avoids conversions between int and bool / char.
It also makes the code more readable.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
The last user of this function was removed by commit
12d4536f7d.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
qemu-timer.h includes qemu-common.h which already includes time.h,
sys/time.h, windows.h, unistd.h, fcntl.h, errno.h and signal.h.
Therefore those include statements are redundant and can be removed.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
- remove qemu_calculate_timeout;
- explicitly size timeout to uint32_t;
- introduce slirp_update_timeout;
- pass NULL as timeout argument to select in case timeout is the maximum
value;
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Paul Brook <paul@codesourcery.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Also delta in qemu_next_alarm_deadline is a 64 bit value so set the
default to INT64_MAX instead of INT32_MAX.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Fix win32_rearm_timer and mm_rearm_timer: they should be able to handle
INT64_MAX as a delta parameter without overflowing.
Also, the next deadline in ms should be calculated rounding down rather
than up (see unix_rearm_timer and dynticks_rearm_timer).
Finally ChangeTimerQueueTimer takes an unsigned long and timeSetEvent
takes an unsigned int as delta, so cast the ms delta to the appropriate
unsigned integer.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Basically, the main wait loop calls qemu_run_all_timers() unconditionally. The
first thing this routine used to do is to see if a timer had been serviced,
and then reset the loop timeout to the next deadline.
However, the new deadlines had not been calculated at that point, as
qemu_run_timers() had not been called yet for each of the clocks. So
qemu_rearm_alarm_timer() would end up with a negative or zero deadline, and
default to setting a 250us timeout for the loop.
As qemu_run_timers() is called for each clock, the real deadlines would be put
in place, but because a loop timeout was already set, the loop timeout would
not be changed.
Once that 250us timeout fired, the real deadline would be used for the
subsequent timeout.
For idle VMs, this effectively doubles the number of times through the loop,
doubling the number of select() system calls, timer calls, etc. putting added
scheduling pressure on the kernel. And under cgroups, this really causes a big
problem because the cgroup code does not scale well.
By simply running the timers before trying to rearm the timer, we always rearm
with a non-zero deadline, effectively halving the number of system calls.
Signed-off-by: Peter Portante <pportant@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Paolo Bonzini
Liu Ping Fan
Stefan Hajnoczi
Alex Bligh
Stefan Weil
Anthony Liguori
Richard Henderson
Stefano Stabellini
Peter Maydell
Andreas Faerber
Peter Portante