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[Qemu-devel] [PATCH V4 07/10] block/qcow2: optimize qcow2_co_pwritev_com
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCH V4 07/10] block/qcow2: optimize qcow2_co_pwritev_compressed |
Date: |
Thu, 20 Jul 2017 16:20:38 +0200 |
if we specify exactly one iov of s->cluster_size bytes we can avoid
the bounce buffer.
Signed-off-by: Peter Lieven <address@hidden>
---
block/qcow2.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 67e48e1..978e8d2 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3393,7 +3393,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs,
uint64_t offset,
struct iovec iov;
z_stream strm;
int ret, out_len;
- uint8_t *buf, *out_buf;
+ uint8_t *buf, *out_buf, *local_buf = NULL;
uint64_t cluster_offset;
if (bytes == 0) {
@@ -3403,8 +3403,8 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs,
uint64_t offset,
return bdrv_truncate(bs->file, cluster_offset, PREALLOC_MODE_OFF,
NULL);
}
- buf = qemu_blockalign(bs, s->cluster_size);
- if (bytes != s->cluster_size) {
+ if (bytes != s->cluster_size || qiov->niov != 1) {
+ buf = local_buf = qemu_blockalign(bs, s->cluster_size);
if (bytes > s->cluster_size ||
offset + bytes != bs->total_sectors << BDRV_SECTOR_BITS)
{
@@ -3413,8 +3413,10 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs,
uint64_t offset,
}
/* Zero-pad last write if image size is not cluster aligned */
memset(buf + bytes, 0, s->cluster_size - bytes);
+ qemu_iovec_to_buf(qiov, 0, buf, bytes);
+ } else {
+ buf = qiov->iov[0].iov_base;
}
- qemu_iovec_to_buf(qiov, 0, buf, bytes);
out_buf = g_malloc(s->cluster_size);
@@ -3482,7 +3484,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs,
uint64_t offset,
success:
ret = 0;
fail:
- qemu_vfree(buf);
+ qemu_vfree(local_buf);
g_free(out_buf);
return ret;
}
--
1.9.1
- Re: [Qemu-devel] [PATCH V4 08/10] block/qcow2: start using the compress format extension, (continued)
[Qemu-devel] [PATCH V4 10/10] block/qcow2: add compress info to image specific info, Peter Lieven, 2017/07/20
[Qemu-devel] [PATCH V4 02/10] qapi/block-core: add Qcow2Compress parameters, Peter Lieven, 2017/07/20
[Qemu-devel] [PATCH V4 07/10] block/qcow2: optimize qcow2_co_pwritev_compressed,
Peter Lieven <=
[Qemu-devel] [PATCH V4 06/10] block/qcow2: simplify ret usage in qcow2_create, Peter Lieven, 2017/07/20
[Qemu-devel] [PATCH V4 05/10] block/qcow2: read and write the compress format extension, Peter Lieven, 2017/07/20
[Qemu-devel] [PATCH V4 03/10] block/qcow2: parse compress create options, Peter Lieven, 2017/07/20
[Qemu-devel] [PATCH V4 09/10] block/qcow2: add lzo compress format, Peter Lieven, 2017/07/20