qemu_cond_wait polling

qemu_cond_wait polling

[Jan Kiszka]

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Hi,

why do we wait on condition variables with silly timeouts (both in
upstream as in qemu-kvm)? There used to be some qemu_aio_poll in
qemu-kvm, but it's no longer there, and upstream never had (unless I
missed something). Is this polling legacy now? Remove it?

Jan


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[Qemu-devel] qemu_cond_wait polling

[Jan Kiszka]

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Hi,

why do we wait on condition variables with silly timeouts (both in
upstream as in qemu-kvm)? There used to be some qemu_aio_poll in
qemu-kvm, but it's no longer there, and upstream never had (unless I
missed something). Is this polling legacy now? Remove it?

Jan


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Re: qemu_cond_wait polling

[Avi Kivity]

On 07/28/2009 10:16 AM, Jan Kiszka wrote:
> Hi,
>
> why do we wait on condition variables with silly timeouts (both in
> upstream as in qemu-kvm)? There used to be some qemu_aio_poll in
> qemu-kvm, but it's no longer there, and upstream never had (unless I
> missed something). Is this polling legacy now? Remove it?
>
>    

Given that all uses are inside while loops, the timeouts are ignored.  
It's completely pointless now.

-- 
error compiling committee.c: too many arguments to function

[Qemu-devel] Re: qemu_cond_wait polling

[Avi Kivity]

On 07/28/2009 10:16 AM, Jan Kiszka wrote:
> Hi,
>
> why do we wait on condition variables with silly timeouts (both in
> upstream as in qemu-kvm)? There used to be some qemu_aio_poll in
> qemu-kvm, but it's no longer there, and upstream never had (unless I
> missed something). Is this polling legacy now? Remove it?
>
>    

Given that all uses are inside while loops, the timeouts are ignored.  
It's completely pointless now.

-- 
error compiling committee.c: too many arguments to function

[PATCH] qemu-kvm: Drop polling property from qemu_cond_wait

[Jan Kiszka]

Avi Kivity wrote:
> On 07/28/2009 10:16 AM, Jan Kiszka wrote:
>> Hi,
>>
>> why do we wait on condition variables with silly timeouts (both in
>> upstream as in qemu-kvm)? There used to be some qemu_aio_poll in
>> qemu-kvm, but it's no longer there, and upstream never had (unless I
>> missed something). Is this polling legacy now? Remove it?
>>
>>    
> 
> Given that all uses are inside while loops, the timeouts are ignored. 
> It's completely pointless now.
> 

Then let's start with removing it from qemu-kvm:

------------>

No caller of qemu_cond_wait makes use of this polling anymore. Remove
it.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

 qemu-kvm.c |    6 +-----
 1 files changed, 1 insertions(+), 5 deletions(-)

diff --git a/qemu-kvm.c b/qemu-kvm.c
index 32dce4a..0615d06 100644
--- a/qemu-kvm.c
+++ b/qemu-kvm.c
@@ -1557,12 +1557,8 @@ static inline unsigned long kvm_get_thread_id(void)
 static void qemu_cond_wait(pthread_cond_t *cond)
 {
     CPUState *env = cpu_single_env;
-    static const struct timespec ts = {
-        .tv_sec = 0,
-        .tv_nsec = 100000,
-    };
 
-    pthread_cond_timedwait(cond, &qemu_mutex, &ts);
+    pthread_cond_wait(cond, &qemu_mutex);
     cpu_single_env = env;
 }
 

Re: [PATCH] qemu-kvm: Drop polling property from qemu_cond_wait

[Avi Kivity]

On 07/28/2009 12:32 PM, Jan Kiszka wrote:
> No caller of qemu_cond_wait makes use of this polling anymore. Remove
> it.
>
>    

Applied, thanks.

-- 
error compiling committee.c: too many arguments to function