* [Qemu-devel] eventfd_signal()
@ 2015-05-08 10:58 Catalin Vasile
2015-05-08 11:24 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Catalin Vasile @ 2015-05-08 10:58 UTC (permalink / raw)
To: qemu-devel
Is eventfd blocking? By that I mean: If I signal the guest for
something, will that thread remain blocked till the guest clears the
interrupt?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] eventfd_signal()
2015-05-08 10:58 [Qemu-devel] eventfd_signal() Catalin Vasile
@ 2015-05-08 11:24 ` Paolo Bonzini
2015-05-08 11:32 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2015-05-08 11:24 UTC (permalink / raw)
To: Catalin Vasile, qemu-devel
On 08/05/2015 12:58, Catalin Vasile wrote:
> Is eventfd blocking? By that I mean: If I signal the guest for
> something, will that thread remain blocked till the guest clears the
> interrupt?
No. If you want that, write 2^64-2 to the eventfd and do a
pfd.fd = ...
pfd.events = POLLOUT;
poll(&pfd, 1, -1);
after the write.
With this algorithm, a write will fail with EINVAL if there is already
another pending write somewhere. The "poll" will still work after the
failed write.
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] eventfd_signal()
2015-05-08 11:24 ` Paolo Bonzini
@ 2015-05-08 11:32 ` Paolo Bonzini
0 siblings, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2015-05-08 11:32 UTC (permalink / raw)
To: Catalin Vasile, qemu-devel
On 08/05/2015 13:24, Paolo Bonzini wrote:
>
>
> On 08/05/2015 12:58, Catalin Vasile wrote:
>> Is eventfd blocking? By that I mean: If I signal the guest for
>> something, will that thread remain blocked till the guest clears the
>> interrupt?
>
> No. If you want that, write 2^64-2 to the eventfd and do a
>
> pfd.fd = ...
> pfd.events = POLLOUT;
> poll(&pfd, 1, -1);
>
> after the write.
>
> With this algorithm, a write will fail with EINVAL if there is already
> another pending write somewhere. The "poll" will still work after the
> failed write.
Oops, EAGAIN...
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-05-08 11:32 UTC | newest]
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2015-05-08 10:58 [Qemu-devel] eventfd_signal() Catalin Vasile
2015-05-08 11:24 ` Paolo Bonzini
2015-05-08 11:32 ` Paolo Bonzini
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