Re: [Qemu-devel] [PATCH 04/12] char: introduce backend tx queue

[Anthony Liguori <anthony@codemonkey.ws>]

On 08/01/2011 10:33 AM, Stefan Hajnoczi wrote:
> On Mon, Aug 1, 2011 at 3:23 PM, Anthony Liguori<aliguori@us.ibm.com>  wrote:
>> While the front tx queue has no flow control, the backend tx queue uses a
>> polling function to determine when the front end can receive data.
>>
>> To convert this to the new queue model, we simply try to flush the backend tx
>> queue whenever we poll.  We then return the remaining space in the queue as
>> the value of the polling function.
>>
>> Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>
>> ---
>>   qemu-char.c |   49 ++++++++++++++++++++++++++++++++++++++++---------
>>   qemu-char.h |    3 ++-
>>   2 files changed, 42 insertions(+), 10 deletions(-)
>>
>> diff --git a/qemu-char.c b/qemu-char.c
>> index 3f9b32c..2746652 100644
>> --- a/qemu-char.c
>> +++ b/qemu-char.c
>> @@ -173,6 +173,11 @@ static size_t char_queue_read(CharQueue *q, void *data, size_t size)
>>      return i;
>>   }
>>
>> +static uint32_t char_queue_get_avail(CharQueue *q)
>> +{
>> +    return sizeof(q->ring) - (q->prod - q->cons);
>> +}
>
> "avail" confuses me.  How many bytes are available for the consumer?
> How many bytes are available for the producer?
>
> How about char_queue_get_space() or char_queue_get_nfree()?

Sure.

Regards,

Anthony Liguori

>
> Stefan
>