Re: [Qemu-devel] [PATCH 4/5] qemu-img bench: Implement -S (step size)

["Denis V. Lunev" <den@openvz.org>]

On 06/03/2016 03:30 PM, Kevin Wolf wrote:
> With this new option, qemu-img bench can be told to advance the current
> offset after each request by a different value than the buffer size.
> This is useful for controlling the conditions for cluster allocation in
> image formats (e.g. qcow2 cluster allocation with COW in front of the
> request, or COW areas that aren't overwritten immediately).
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   qemu-img-cmds.hx |  4 ++--
>   qemu-img.c       | 25 +++++++++++++++++++++----
>   qemu-img.texi    |  6 ++++--
>   3 files changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
> index b9b521e..f5d0098 100644
> --- a/qemu-img-cmds.hx
> +++ b/qemu-img-cmds.hx
> @@ -10,9 +10,9 @@ STEXI
>   ETEXI
>   
>   DEF("bench", img_bench,
> -    "bench [-c count] [-d depth] [-f fmt] [-n] [-o offset] [-q] [-s buffer_size] [-t cache] [-w] filename")
> +    "bench [-c count] [-d depth] [-f fmt] [-n] [-o offset] [-q] [-s buffer_size] [-S step_size] [-t cache] [-w] filename")
>   STEXI
> -@item bench [-c @var{count}] [-d @var{depth}] [-f @var{fmt}] [-n] [-o @var{offset}] [-q] [-s @var{buffer_size}] [-t @var{cache}] [-w] @var{filename}
> +@item bench [-c @var{count}] [-d @var{depth}] [-f @var{fmt}] [-n] [-o @var{offset}] [-q] [-s @var{buffer_size}] [-S @var{step_size}] [-t @var{cache}] [-w] @var{filename}
>   ETEXI
>   
>   DEF("check", img_check,
> diff --git a/qemu-img.c b/qemu-img.c
> index fcac8b8..ff99181 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -3464,6 +3464,7 @@ typedef struct BenchData {
>       uint64_t image_size;
>       bool write;
>       int bufsize;
> +    int step;
>       int nrreq;
>       int n;
>       uint8_t *buf;
> @@ -3500,7 +3501,7 @@ static void bench_cb(void *opaque, int ret)
>               exit(EXIT_FAILURE);
>           }
>           b->in_flight++;
> -        b->offset += b->bufsize;
> +        b->offset += b->step;
>           b->offset %= b->image_size;
>       }
>   }
> @@ -3516,6 +3517,7 @@ static int img_bench(int argc, char **argv)
>       int depth = 64;
>       int64_t offset = 0;
>       size_t bufsize = 4096;
> +    size_t step = 0;
>       int64_t image_size;
>       BlockBackend *blk = NULL;
>       BenchData data = {};
> @@ -3530,7 +3532,7 @@ static int img_bench(int argc, char **argv)
>               {"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
>               {0, 0, 0, 0}
>           };
> -        c = getopt_long(argc, argv, "hc:d:f:no:qs:t:w", long_options, NULL);
> +        c = getopt_long(argc, argv, "hc:d:f:no:qs:S:t:w", long_options, NULL);
>           if (c == -1) {
>               break;
>           }
> @@ -3598,6 +3600,20 @@ static int img_bench(int argc, char **argv)
>               bufsize = sval;
>               break;
>           }
> +        case 'S':
> +        {
> +            int64_t sval;
> +            char *end;
> +
> +            sval = qemu_strtosz_suffix(optarg, &end, QEMU_STRTOSZ_DEFSUFFIX_B);
> +            if (sval < 0 || sval > INT_MAX || *end) {
> +                error_report("Invalid step size specified");
> +                return 1;
> +            }
> +
> +            step = sval;
> +            break;
> +        }
>           case 't':
>               ret = bdrv_parse_cache_mode(optarg, &flags, &writethrough);
>               if (ret < 0) {
> @@ -3637,15 +3653,16 @@ static int img_bench(int argc, char **argv)
>           .blk        = blk,
>           .image_size = image_size,
>           .bufsize    = bufsize,
> +        .step       = step ?: bufsize,
>           .nrreq      = depth,
>           .n          = count,
>           .offset     = offset,
>           .write      = is_write,
>       };
>       printf("Sending %d %s requests, %d bytes each, %d in parallel "
> -           "(starting at offset %" PRId64 ")\n",
> +           "(starting at offset %" PRId64 ", step size %d)\n",
>              data.n, data.write ? "write" : "read", data.bufsize, data.nrreq,
> -           data.offset);
> +           data.offset, data.step);
>   
>       data.buf = blk_blockalign(blk, data.nrreq * data.bufsize);
>       memset(data.buf, 0, data.nrreq * data.bufsize);
> diff --git a/qemu-img.texi b/qemu-img.texi
> index c37380e..6b03d3f 100644
> --- a/qemu-img.texi
> +++ b/qemu-img.texi
> @@ -131,14 +131,16 @@ Skip the creation of the target volume
>   Command description:
>   
>   @table @option
> -@item bench [-c @var{count}] [-d @var{depth}] [-f @var{fmt}] [-n] [-o @var{offset}] [-q] [-s @var{buffer_size}] [-t @var{cache}] [-w] @var{filename}
> +@item bench [-c @var{count}] [-d @var{depth}] [-f @var{fmt}] [-n] [-o @var{offset}] [-q] [-s @var{buffer_size}] [-S @var{step_size}] [-t @var{cache}] [-w] @var{filename}
>   
>   Run a simple sequential I/O benchmark on the specified image. If @code{-w} is
>   specified, a write test is performed, otherwise a read test is performed.
>   
>   A total number of @var{count} I/O requests is performed, each @var{buffer_size}
>   bytes in size, and with @var{depth} requests in parallel. The first request
> -starts at the position given by @var{offset}.
> +starts at the position given by @var{offset}, each following request increases
> +the current position by @var{step_size}. If @var{step_size} is not given,
> +@var{buffer_size} is used for its value.
>   
>   If @code{-n} is specified, the native AIO backend is used if possible. On
>   Linux, this option only works if @code{-t none} or @code{-t directsync} is
Reviewed-by: Denis V. Lunev <den@openvz.org>