[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PULL 05/20] buffer: add buffer_shrink
From: |
Gerd Hoffmann |
Subject: |
[Qemu-devel] [PULL 05/20] buffer: add buffer_shrink |
Date: |
Mon, 16 Nov 2015 18:25:20 +0100 |
Signed-off-by: Gerd Hoffmann <address@hidden>
Reviewed-by: Peter Lieven <address@hidden>
Reviewed-by: Daniel P. Berrange <address@hidden>
Message-id: address@hidden
---
include/qemu/buffer.h | 10 ++++++++++
util/buffer.c | 20 +++++++++++++++++++-
2 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/include/qemu/buffer.h b/include/qemu/buffer.h
index 1358df1..0a69b3a 100644
--- a/include/qemu/buffer.h
+++ b/include/qemu/buffer.h
@@ -52,6 +52,16 @@ void buffer_init(Buffer *buffer, const char *name, ...)
GCC_FMT_ATTR(2, 3);
/**
+ * buffer_shrink:
+ * @buffer: the buffer object
+ *
+ * Try to shrink the buffer. Checks current buffer capacity and size
+ * and reduces capacity in case only a fraction of the buffer is
+ * actually used.
+ */
+void buffer_shrink(Buffer *buffer);
+
+/**
* buffer_reserve:
* @buffer: the buffer object
* @len: the minimum required free space
diff --git a/util/buffer.c b/util/buffer.c
index e8f798e..234e33d 100644
--- a/util/buffer.c
+++ b/util/buffer.c
@@ -20,7 +20,8 @@
#include "qemu/buffer.h"
-#define BUFFER_MIN_INIT_SIZE 4096
+#define BUFFER_MIN_INIT_SIZE 4096
+#define BUFFER_MIN_SHRINK_SIZE 65536
void buffer_init(Buffer *buffer, const char *name, ...)
{
@@ -31,6 +32,23 @@ void buffer_init(Buffer *buffer, const char *name, ...)
va_end(ap);
}
+void buffer_shrink(Buffer *buffer)
+{
+ /*
+ * Only shrink in case the used size is *much* smaller than the
+ * capacity, to avoid bumping up & down the buffers all the time.
+ * realloc() isn't exactly cheap ...
+ */
+ if (buffer->offset < (buffer->capacity >> 3) &&
+ buffer->capacity > BUFFER_MIN_SHRINK_SIZE) {
+ return;
+ }
+
+ buffer->capacity = pow2ceil(buffer->offset);
+ buffer->capacity = MAX(buffer->capacity, BUFFER_MIN_SHRINK_SIZE);
+ buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
+}
+
void buffer_reserve(Buffer *buffer, size_t len)
{
if ((buffer->capacity - buffer->offset) < len) {
--
1.8.3.1
- [Qemu-devel] [PULL 10/20] vnc: zap dead code, (continued)
- [Qemu-devel] [PULL 10/20] vnc: zap dead code, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 06/20] buffer: add tracing, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 08/20] vnc: kill jobs queue buffer, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 02/20] buffer: add buffer_init, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 18/20] buffer: factor out buffer_adj_size, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 16/20] vnc: recycle empty vs->output buffer, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 19/20] buffer: allow a buffer to shrink gracefully, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 11/20] vnc: add vnc_width+vnc_height helpers, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 03/20] buffer: add buffer_move_empty, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 14/20] vnc: only alloc server surface with clients connected, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 05/20] buffer: add buffer_shrink,
Gerd Hoffmann <=
- [Qemu-devel] [PULL 20/20] vnc: fix mismerge, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 07/20] vnc: attach names to buffers, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 17/20] buffer: factor out buffer_req_size, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 12/20] vnc: factor out vnc_update_server_surface, Gerd Hoffmann, 2015/11/16
- [Qemu-devel] [PULL 15/20] vnc: fix local state init, Gerd Hoffmann, 2015/11/16
- Re: [Qemu-devel] [PULL for-2.5 00/20] vnc: buffer code improvements, bugfixes., Peter Maydell, 2015/11/17