Re: [Qemu-devel] [PATCH 19/19] buffer: allow a buffer to shrink gracefully

[Daniel P. Berrange]

On Fri, Oct 30, 2015 at 12:10:14PM +0100, Gerd Hoffmann wrote:
> From: Peter Lieven <address@hidden>
> 
> the idea behind this patch is to allow the buffer to shrink, but
> make this a seldom operation. The buffers average size is measured
> exponentionally smoothed with am alpha of 1/128.

s/am/an/

> 
> Signed-off-by: Peter Lieven <address@hidden>
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
>  include/qemu/buffer.h |  1 +
>  util/buffer.c         | 34 ++++++++++++++++++++++++++++------
>  2 files changed, 29 insertions(+), 6 deletions(-)


> diff --git a/util/buffer.c b/util/buffer.c
> index fe5a44e..5461f86 100644
> --- a/util/buffer.c
> +++ b/util/buffer.c
> @@ -23,6 +23,7 @@
>  
>  #define BUFFER_MIN_INIT_SIZE     4096
>  #define BUFFER_MIN_SHRINK_SIZE  65536
> +#define BUFFER_AVG_SIZE_SHIFT       7
>  
>  static size_t buffer_req_size(Buffer *buffer, size_t len)
>  {
> @@ -37,6 +38,11 @@ static void buffer_adj_size(Buffer *buffer, size_t len)
>      buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
>      trace_buffer_resize(buffer->name ?: "unnamed",
>                          old, buffer->capacity);
> +
> +    /* make it even harder for the buffer to shrink, reset average size
> +     * to currenty capacity if it is larger than the average. */

s/currenty/current/

Reviewed-by: Daniel P. Berrange <address@hidden>


Regards,
Daniel
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