From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33011) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtXTF-0005pi-PV for qemu-devel@nongnu.org; Tue, 03 Nov 2015 04:01:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZtXTE-0006qk-AH for qemu-devel@nongnu.org; Tue, 03 Nov 2015 04:01:37 -0500 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:48060 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtXTE-0006qX-1v for qemu-devel@nongnu.org; Tue, 03 Nov 2015 04:01:36 -0500 From: Peter Lieven Date: Tue, 3 Nov 2015 10:01:16 +0100 Message-Id: <1446541276-32467-3-git-send-email-pl@kamp.de> In-Reply-To: <1446541276-32467-1-git-send-email-pl@kamp.de> References: <1446541276-32467-1-git-send-email-pl@kamp.de> Subject: [Qemu-devel] [PATCH 2/2] io/buffer: avoid memmove at each qio_buffer_advance List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Lieven , kraxel@redhat.com memmove isn't exactly cheap at it involves temporary buffers if the memory areas are overlapping. So make qio_buffer_advance basically a pointer adjustment, but still keep the wasted memory in reasonable limits. Signed-off-by: Peter Lieven --- include/io/buffer.h | 2 ++ io/buffer.c | 43 ++++++++++++++++++++++++++++++++----------- 2 files changed, 34 insertions(+), 11 deletions(-) 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; }; /** diff --git a/io/buffer.c b/io/buffer.c index d2a6043..f1e4570 100644 --- a/io/buffer.c +++ b/io/buffer.c @@ -21,24 +21,27 @@ #include "io/buffer.h" #include "trace.h" -#define QIO_BUFFER_MIN_INIT_SIZE 4096 -#define QIO_BUFFER_MIN_SHRINK_SIZE 65536 +#define QIO_BUFFER_MIN_INIT_SIZE 4096 +#define QIO_BUFFER_MIN_SHRINK_SIZE 65536 +#define QIO_BUFFER_MAX_WASTED_SIZE 1048576 /* define the factor alpha for the expentional smoothing * that is used in the average size calculation. a shift * of 7 results in an alpha of 1/2^7. */ -#define QIO_BUFFER_AVG_SIZE_SHIFT 7 +#define QIO_BUFFER_AVG_SIZE_SHIFT 7 static size_t buf_req_size(QIOBuffer *buffer, size_t len) { return MAX(QIO_BUFFER_MIN_INIT_SIZE, - pow2ceil(buffer->offset + len)); + pow2ceil(buffer->base_offs + buffer->offset + len)); } static void buf_adj_size(QIOBuffer *buffer, size_t len) { size_t old = buffer->capacity; buffer->capacity = buf_req_size(buffer, len); - buffer->buffer = g_realloc(buffer->buffer, buffer->capacity); + buffer->base_ptr = g_realloc(buffer->base_ptr, buffer->capacity); + buffer->buffer = buffer->base_ptr + buffer->base_offs; + trace_qio_buffer_resize(buffer->name ?: "unnamed", old, buffer->capacity); @@ -105,17 +108,21 @@ uint8_t *qio_buffer_end(QIOBuffer *buffer) void qio_buffer_reset(QIOBuffer *buffer) { buffer->offset = 0; + buffer->base_offs = 0; + buffer->buffer = buffer->base_ptr; qio_buffer_shrink(buffer); } void qio_buffer_free(QIOBuffer *buffer) { trace_qio_buffer_free(buffer->name ?: "unnamed", buffer->capacity); - g_free(buffer->buffer); + g_free(buffer->base_ptr); g_free(buffer->name); buffer->offset = 0; + buffer->base_offs = 0; buffer->capacity = 0; buffer->buffer = NULL; + buffer->base_ptr = NULL; buffer->name = NULL; } @@ -127,10 +134,18 @@ void qio_buffer_append(QIOBuffer *buffer, const void *data, size_t len) void qio_buffer_advance(QIOBuffer *buffer, size_t len) { - memmove(buffer->buffer, buffer->buffer + len, - (buffer->offset - len)); + if (buffer->offset - len == 0) { + return qio_buffer_reset(buffer); + } + buffer->buffer += len; + buffer->base_offs += len; buffer->offset -= len; - qio_buffer_shrink(buffer); + if (buffer->base_offs > QIO_BUFFER_MAX_WASTED_SIZE) { + memmove(buffer->base_ptr, buffer->buffer, buffer->offset); + buffer->buffer = buffer->base_ptr; + buffer->base_offs = 0; + qio_buffer_shrink(buffer); + } } void qio_buffer_move_empty(QIOBuffer *to, QIOBuffer *from) @@ -140,14 +155,18 @@ void qio_buffer_move_empty(QIOBuffer *to, QIOBuffer *from) from->name ?: "unnamed"); assert(to->offset == 0); - g_free(to->buffer); + g_free(to->base_ptr); to->offset = from->offset; to->capacity = from->capacity; to->buffer = from->buffer; + to->base_offs = from->base_offs; + to->base_ptr = from->base_ptr; from->offset = 0; from->capacity = 0; from->buffer = NULL; + from->base_offs = 0; + from->base_ptr = NULL; } void qio_buffer_move(QIOBuffer *to, QIOBuffer *from) @@ -164,8 +183,10 @@ void qio_buffer_move(QIOBuffer *to, QIOBuffer *from) qio_buffer_reserve(to, from->offset); qio_buffer_append(to, from->buffer, from->offset); - g_free(from->buffer); + g_free(from->base_ptr); from->offset = 0; from->capacity = 0; from->buffer = NULL; + from->base_offs = 0; + from->base_ptr = NULL; } -- 1.9.1