since the convert process is basically a sync operation it might
be benificial in some case to change the hardcoded I/O buffer
size to an alternate (greater) value.
Signed-off-by: Peter Lieven <p...@kamp.de>
---
qemu-img-cmds.hx | 4 ++--
qemu-img.c | 25 ++++++++++++++++++++-----
qemu-img.texi | 4 +++-
3 files changed, 25 insertions(+), 8 deletions(-)
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index da1d965..e0b8ab4 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -34,9 +34,9 @@ STEXI
ETEXI
DEF("convert", img_convert,
- "convert [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-O output_fmt] [-o
options] [-s snapshot_name] [-S sparse_size] filename [filename2 [...]]
output_filename")
+ "convert [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-O output_fmt] [-o
options] [-s snapshot_name] [-S sparse_size] [-m iobuf_size] filename
[filename2 [...]] output_filename")
STEXI
-@item convert [-c] [-p] [-q] [-n] [-f @var{fmt}] [-t @var{cache}] [-O
@var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S
@var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
+@item convert [-c] [-p] [-q] [-n] [-f @var{fmt}] [-t @var{cache}] [-O
@var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S
@var{sparse_size}] [-m @var{iobuf_size}] @var{filename} [@var{filename2} [...]]
@var{output_filename}
ETEXI
DEF("info", img_info,
diff --git a/qemu-img.c b/qemu-img.c
index e2d1a0a..0ce5d14 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -105,6 +105,7 @@ static void help(void)
" conversion. If the number of bytes is 0, the source will
not be scanned for\n"
" unallocated or zero sectors, and the destination image will
always be\n"
" fully allocated\n"
+ " '-m' specify I/O buffer size in bytes (default 2M)\n"
" '--output' takes the format in which the output must be done
(human or json)\n"
" '-n' skips the target volume creation (useful if the volume is
created\n"
" prior to running qemu-img)\n"
@@ -1135,6 +1136,7 @@ static int img_convert(int argc, char **argv)
sector_num_next_status = 0;
uint64_t bs_sectors;
uint8_t * buf = NULL;
+ size_t bufsectors = IO_BUF_SIZE / BDRV_SECTOR_SIZE;
const uint8_t *buf1;
BlockDriverInfo bdi;
QEMUOptionParameter *param = NULL, *create_options = NULL;
@@ -1152,7 +1154,7 @@ static int img_convert(int argc, char **argv)
compress = 0;
skip_create = 0;
for(;;) {
- c = getopt(argc, argv, "f:O:B:s:hce6o:pS:t:qn");
+ c = getopt(argc, argv, "f:O:B:s:hce6o:pS:m:t:qn");
if (c == -1) {
break;
}
@@ -1200,6 +1202,19 @@ static int img_convert(int argc, char **argv)
min_sparse = sval / BDRV_SECTOR_SIZE;
break;
}
+ case 'm':
+ {
+ int64_t sval;
+ char *end;
+ sval = strtosz_suffix(optarg, &end, STRTOSZ_DEFSUFFIX_B);
+ if (sval < BDRV_SECTOR_SIZE || *end) {
+ error_report("Invalid I/O buffer size specified");
+ return 1;
+ }
+
+ bufsectors = sval / BDRV_SECTOR_SIZE;
+ break;
+ }
case 'p':
progress = 1;
break;
@@ -1371,7 +1386,7 @@ static int img_convert(int argc, char **argv)
bs_i = 0;
bs_offset = 0;
bdrv_get_geometry(bs[0], &bs_sectors);
- buf = qemu_blockalign(out_bs, IO_BUF_SIZE);
+ buf = qemu_blockalign(out_bs, bufsectors * BDRV_SECTOR_SIZE);
if (skip_create) {
int64_t output_length = bdrv_getlength(out_bs);
@@ -1394,7 +1409,7 @@ static int img_convert(int argc, char **argv)
goto out;
}
cluster_size = bdi.cluster_size;
- if (cluster_size <= 0 || cluster_size > IO_BUF_SIZE) {
+ if (cluster_size <= 0 || cluster_size > bufsectors * BDRV_SECTOR_SIZE)
{
error_report("invalid cluster size");
ret = -1;
goto out;
@@ -1531,8 +1546,8 @@ static int img_convert(int argc, char **argv)
sector_num_next_status = sector_num + n1;
}
- if (nb_sectors >= (IO_BUF_SIZE / 512)) {
- n = (IO_BUF_SIZE / 512);
+ if (nb_sectors >= bufsectors) {
+ n = bufsectors;
} else {
n = nb_sectors;
}
diff --git a/qemu-img.texi b/qemu-img.texi
index da36975..87f9d0f 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -179,7 +179,7 @@ Error on reading data
@end table
-@item convert [-c] [-p] [-n] [-f @var{fmt}] [-t @var{cache}] [-O
@var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S
@var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
+@item convert [-c] [-p] [-n] [-f @var{fmt}] [-t @var{cache}] [-O
@var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S
@var{sparse_size}] [-m @var{iobuf_size}] @var{filename} [@var{filename2} [...]]
@var{output_filename}
Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to
disk image @var{output_filename}
using format @var{output_fmt}. It can be optionally compressed (@code{-c}
@@ -199,6 +199,8 @@ conversion. If @var{sparse_size} is 0, the source will not
be scanned for
unallocated or zero sectors, and the destination image will always be
fully allocated.
+@var{iobuf_size} indicates the size of the I/O buffer (defaults to 2M).
+
You can use the @var{backing_file} option to force the output image to be
created as a copy on write image of the specified base image; the
@var{backing_file} should have the same content as the input's base image,
--
1.7.9.5
