[Xen-devel] [PATCH v6 0/5] prevent QEMU from waking up needlessly

[Stefano Stabellini <Stefano.Stabellini@xxxxxxxxxxxxx>]

Hi all,
this small patch series prevents QEMU from waking up needlessly on Xen
several times a second in order to check some timers.



The first patch stops QEMU from emulating the PIT on Xen, the second
patch disables the rtc_clock entirely.

The third patch fixes win32_rearm_timer and mm_rearm_timer that
risk an overflow if INT64_MAX is passed as delta.

The fourth patch changes qemu_next_alarm_deadline only to check the
expire time of a clock if it is enabled.

Finally the last patch makes main_loop_wait wait indefinitely on select
unless we actually need a timeout.



Changes in v6:

- rebase on 7672725d41d1a04195affc1a7bd5676ba6314b14;

- dropped the buffered IO patch, that has been handled separately from
this series.


Changes in v5:

- remove the last patch to increase the timeout to 1h, replace it with a
patch to wait indefinitely on select unless we need a timeout.


Changes in v4:

- do not initialize pcspk on xen;

- disable rtc_clock only when it points to the host_clock (the default);

- make sure it compiles on older xen versions.


Changes in v3:

- added a new patch to fix win32_rearm_timer and mm_rearm_timer, that
risk an overflow if INT64_MAX is passed as delta.



Shortlog and diffstat follow:

Stefano Stabellini (5):
      xen: do not initialize the interval timer and PCSPK emulator
      xen: disable rtc_clock
      timers: the rearm function should be able to handle delta = INT64_MAX
      qemu_next_alarm_deadline: check the expire time of a clock only if it is 
enabled
      main_loop_wait: block indefinitely

 async.c          |    2 +-
 hw/pc.c          |    9 ++++++---
 main-loop.c      |   23 ++++++++++++++---------
 main-loop.h      |    2 +-
 qemu-timer.c     |   33 +++++++++++++++++----------------
 qemu-timer.h     |    1 -
 qemu-tool.c      |    4 ++++
 slirp/libslirp.h |    1 +
 slirp/slirp.c    |    7 +++++++
 xen-all.c        |    4 ++++
 10 files changed, 55 insertions(+), 31 deletions(-)


A git tree, based on 7672725d41d1a04195affc1a7bd5676ba6314b14, is available 
here:

git://xenbits.xen.org/people/sstabellini/qemu-dm.git timers-6

Cheers,

Stefano

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