Re: [Qemu-devel] [PATCH 2/2] io/buffer: avoid memmove at each qio_buffer_advance

[Peter Lieven <pl@kamp.de>]

Am 03.11.2015 um 11:52 schrieb Gerd Hoffmann:
>> diff --git a/include/io/buffer.h b/include/io/buffer.h
>> index f63869e..43688cc 100644
>> --- a/include/io/buffer.h
>> +++ b/include/io/buffer.h
>> @@ -39,6 +39,8 @@ struct QIOBuffer {
>>       size_t offset;
>>       uint64_t avg_size;
>>       uint8_t *buffer;
>> +    size_t base_offs;
>> +    uint8_t *base_ptr;
> Why a separate base_ptr?
>
> While being at it I'd much prefer to replace offset with start & end.
> The buffer content is buffer[start] ... buffer[end-1] then.
>
> We can allow the buffer to wrap around, i.e. end < start.  Buffer
> content is buf[start] ... buffer[size-1] and buffer[0] .. buffer[end-1]
> then.  Makes the buffer management a bit more complicated, but we never
> have to memmove then (except when changing buffer size) and the
> WASTED_SIZE logic isn't needed too ...

Then drop this patch and try to use your approach for 2.6+

Peter