On Tue, Sep 20, 2011 at 2:41 PM, Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> On 19/09/2011 22:21, "Daniel Castro" <evil.dani@xxxxxxxxx> wrote:
>
>> Greetings all.
>>
>> Some small question regarding schedule poll operation hypercall.
>>
>> 1. struct sched_poll poll.timeout is measured in what unit of time?
>> Secs, ms? ns?
>
> It is an absolute system time (rather than a duration), in nanoseconds.
really an absolute system time?
When the timeout is set and the timeout is reached, the system behaves
like if the event had been received? i.e the bit is changed?
>
>> 2. After issuing the hypercall_sched_op(SCHEDOP_poll, &poll); if no
>> timeout is used in poll struct how long will I yield the CPU?
>
> Until one of the specified event channel ports is pending.
If the channel port never changes (the event never arrives) then I
would yield for ever?
>
>> 3. If I issue the hypercall and the event never comes is it possible
>> to to yield the CPU for ever?
>
> Yes, if you do not specify a timeout.
Keir thanks for the answer.
I am trying to read from xenstore, so I have the following:
I write on my xenstore ring the query I want, then,
hypercall_event_channel_op(EVTCHNOP_send ...
If I read the ring inmediatly the answer is not ready so I issue a
hypercall_sched_op(SCHEDOP_poll, &poll);
But while I am entering the yield state the answer comes, so the event
is never seen because it has already been delivered.
If I use some way to wait (just for very brief instant) after the
event_channel_op send then, when I check the ring the answer is there;
And I do not need to yield the CPU.
Should I issue the wait after the send, rather than when I am about to
read the answer?
Thanks,
Daniel
>
> -- Keir
>
>> Thanks you very much for answering these questions.
>>
>> Daniel Castro
>
>
>
--
+-=====---------------------------+
| +---------------------------------+ | This space intentionally blank
for notetaking.
| | | Daniel Castro, |
| | | Consultant/Programmer.|
| | | U Andes |
+-------------------------------------+
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home