Re: [Qemu-devel] [PATCH v4 01/15] coroutine: add co_sleep_ns() coroutine sleep function

[Stefan Hajnoczi]

On Thu, Jan 12, 2012 at 10:13 AM, Kevin Wolf <address@hidden> wrote:
> Am 06.01.2012 15:01, schrieb Stefan Hajnoczi:
>> Signed-off-by: Stefan Hajnoczi <address@hidden>
>> ---
>>  Makefile.objs          |    1 +
>>  qemu-coroutine-sleep.c |   38 ++++++++++++++++++++++++++++++++++++++
>>  qemu-coroutine.h       |    6 ++++++
>>  3 files changed, 45 insertions(+), 0 deletions(-)
>>  create mode 100644 qemu-coroutine-sleep.c
>
>> diff --git a/qemu-coroutine.h b/qemu-coroutine.h
>> index 8a55fe1..bae1ffe 100644
>> --- a/qemu-coroutine.h
>> +++ b/qemu-coroutine.h
>> @@ -17,6 +17,7 @@
>>
>>  #include <stdbool.h>
>>  #include "qemu-queue.h"
>> +#include "qemu-timer.h"
>>
>>  /**
>>   * Coroutines are a mechanism for stack switching and can be used for
>> @@ -199,4 +200,9 @@ void qemu_co_rwlock_wrlock(CoRwlock *lock);
>>   */
>>  void qemu_co_rwlock_unlock(CoRwlock *lock);
>>
>> +/**
>> + * Yield the coroutine for a given duration
>> + */
>> +void coroutine_fn co_sleep_ns(QEMUClock *clock, int64_t ns);
>> +
>>  #endif /* QEMU_COROUTINE_H */
>
> As you mentioned on IRC yesterday, timers don't work in the tools. There
> should probably be a warning in the comment (or a fix before this is merged)

This is something I'm looking at right now and will probably want to
discuss with Paolo.

In a coroutine we're probably using a main loop and timers should be
available there.  In general, the problem we're starting to see is
that some block layer features are using timers (I/O throttling, QED
deferred dirty bit clearing, image streaming).  The question is do we
isolate this functionality so it is unavailable from a qemu-tool world
when there's no main loop, or do we move everything into a main loop?

Stefan