Re: [Qemu-devel] [PATCH v2 5/5] qemu-img bench: Add --flush-interval

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

On 06/06/2016 03:46 PM, Kevin Wolf wrote:
> This options allows to flush the image periodically during write tests.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   qemu-img-cmds.hx |  4 +--
>   qemu-img.c       | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++------
>   qemu-img.texi    |  8 ++++-
>   3 files changed, 95 insertions(+), 12 deletions(-)
>
> diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
> index 05a2991..7e95b2d 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] [--pattern=pattern] [-q] [-s buffer_size] [-S step_size] [-t cache] [-w] filename")
> +    "bench [-c count] [-d depth] [-f fmt] [--flush-interval=flush_interval] [-n] [--no-drain] [-o offset] [--pattern=pattern] [-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}] [--pattern=@var{pattern}] [-q] [-s @var{buffer_size}] [-S @var{step_size}] [-t @var{cache}] [-w] @var{filename}
> +@item bench [-c @var{count}] [-d @var{depth}] [-f @var{fmt}] [--flush-interval=@var{flush_interval}] [-n] [--no-drain] [-o @var{offset}] [--pattern=@var{pattern}] [-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 c5e2638..04cddab 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -54,6 +54,8 @@ enum {
>       OPTION_OBJECT = 258,
>       OPTION_IMAGE_OPTS = 259,
>       OPTION_PATTERN = 260,
> +    OPTION_FLUSH_INTERVAL = 261,
> +    OPTION_NO_DRAIN = 262,
>   };
>   
>   typedef enum OutputFormat {
> @@ -3468,13 +3470,24 @@ typedef struct BenchData {
>       int step;
>       int nrreq;
>       int n;
> +    int flush_interval;
> +    bool drain_on_flush;
>       uint8_t *buf;
>       QEMUIOVector *qiov;
>   
>       int in_flight;
> +    bool in_flush;
>       uint64_t offset;
>   } BenchData;
>   
> +static void bench_undrained_flush_cb(void *opaque, int ret)
> +{
> +    if (ret < 0) {
> +        error_report("Failed flush request: %s\n", strerror(-ret));
> +        exit(EXIT_FAILURE);
> +    }
> +}
> +
>   static void bench_cb(void *opaque, int ret)
>   {
>       BenchData *b = opaque;
> @@ -3484,9 +3497,39 @@ static void bench_cb(void *opaque, int ret)
>           error_report("Failed request: %s\n", strerror(-ret));
>           exit(EXIT_FAILURE);
>       }
> -    if (b->in_flight > 0) {
> +
> +    if (b->in_flush) {
> +        /* Just finished a flush with drained queue: Start next requests */
> +        assert(b->in_flight == 0);
> +        b->in_flush = false;
> +    } else if (b->in_flight > 0) {
> +        int remaining = b->n - b->in_flight;
> +
>           b->n--;
>           b->in_flight--;
> +
> +        /* Time for flush? Drain queue if requested, then flush */
> +        if (b->flush_interval && remaining % b->flush_interval == 0) {
> +            if (!b->in_flight || !b->drain_on_flush) {
> +                BlockCompletionFunc *cb;
> +
> +                if (b->drain_on_flush) {
> +                    b->in_flush = true;
> +                    cb = bench_cb;
> +                } else {
> +                    cb = bench_undrained_flush_cb;
> +                }
> +
> +                acb = blk_aio_flush(b->blk, cb, b);
> +                if (!acb) {
> +                    error_report("Failed to issue flush request");
> +                    exit(EXIT_FAILURE);
> +                }
> +            }
> +            if (b->drain_on_flush) {
> +                return;
> +            }
> +        }
>       }
>   
>       while (b->n > b->in_flight && b->in_flight < b->nrreq) {
> @@ -3520,6 +3563,8 @@ static int img_bench(int argc, char **argv)
>       size_t bufsize = 4096;
>       int pattern = 0;
>       size_t step = 0;
> +    int flush_interval = 0;
> +    bool drain_on_flush = true;
>       int64_t image_size;
>       BlockBackend *blk = NULL;
>       BenchData data = {};
> @@ -3531,8 +3576,10 @@ static int img_bench(int argc, char **argv)
>       for (;;) {
>           static const struct option long_options[] = {
>               {"help", no_argument, 0, 'h'},
> +            {"flush-interval", required_argument, 0, OPTION_FLUSH_INTERVAL},
>               {"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
>               {"pattern", required_argument, 0, OPTION_PATTERN},
> +            {"no-drain", no_argument, 0, OPTION_NO_DRAIN},
>               {0, 0, 0, 0}
>           };
>           c = getopt_long(argc, argv, "hc:d:f:no:qs:S:t:w", long_options, NULL);
> @@ -3640,6 +3687,20 @@ static int img_bench(int argc, char **argv)
>               }
>               break;
>           }
> +        case OPTION_FLUSH_INTERVAL:
> +        {
> +            char *end;
> +            errno = 0;
> +            flush_interval = strtoul(optarg, &end, 0);
> +            if (errno || *end || flush_interval > INT_MAX) {
> +                error_report("Invalid flush interval specified");
> +                return 1;
> +            }
> +            break;
> +        }
> +        case OPTION_NO_DRAIN:
> +            drain_on_flush = false;
> +            break;
>           case OPTION_IMAGE_OPTS:
>               image_opts = true;
>               break;
> @@ -3651,6 +3712,17 @@ static int img_bench(int argc, char **argv)
>       }
>       filename = argv[argc - 1];
>   
> +    if (!is_write && flush_interval) {
> +        error_report("--flush-interval is only available in write tests");
> +        ret = -1;
> +        goto out;
> +    }
> +    if (flush_interval && flush_interval < depth) {
> +        error_report("Flush interval can't be smaller than depth");
> +        ret = -1;
> +        goto out;
> +    }
> +
>       blk = img_open(image_opts, filename, fmt, flags, writethrough, quiet);
>       if (!blk) {
>           ret = -1;
> @@ -3664,19 +3736,24 @@ static int img_bench(int argc, char **argv)
>       }
>   
>       data = (BenchData) {
> -        .blk        = blk,
> -        .image_size = image_size,
> -        .bufsize    = bufsize,
> -        .step       = step ?: bufsize,
> -        .nrreq      = depth,
> -        .n          = count,
> -        .offset     = offset,
> -        .write      = is_write,
> +        .blk            = blk,
> +        .image_size     = image_size,
> +        .bufsize        = bufsize,
> +        .step           = step ?: bufsize,
> +        .nrreq          = depth,
> +        .n              = count,
> +        .offset         = offset,
> +        .write          = is_write,
> +        .flush_interval = flush_interval,
> +        .drain_on_flush = drain_on_flush,
>       };
>       printf("Sending %d %s requests, %d bytes each, %d in parallel "
>              "(starting at offset %" PRId64 ", step size %d)\n",
>              data.n, data.write ? "write" : "read", data.bufsize, data.nrreq,
>              data.offset, data.step);
> +    if (flush_interval) {
> +        printf("Sending flush every %d requests\n", flush_interval);
> +    }
>   
>       data.buf = blk_blockalign(blk, data.nrreq * data.bufsize);
>       memset(data.buf, pattern, data.nrreq * data.bufsize);
> diff --git a/qemu-img.texi b/qemu-img.texi
> index ccc0b51..cbe50e9 100644
> --- a/qemu-img.texi
> +++ b/qemu-img.texi
> @@ -131,7 +131,7 @@ 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}] [--pattern=@var{pattern}] [-q] [-s @var{buffer_size}] [-S @var{step_size}] [-t @var{cache}] [-w] @var{filename}
> +@item bench [-c @var{count}] [-d @var{depth}] [-f @var{fmt}] [--flush-interval=@var{flush_interval}] [-n] [--no-drain] [-o @var{offset}] [--pattern=@var{pattern}] [-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.
> @@ -142,6 +142,12 @@ 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 @var{flush_interval} is specified for a write test, the request queue is
> +drained and a flush is issued before new writes are made whenever the number of
> +remaining requests is a multiple of @var{flush_interval}. If additionally
> +@code{--no-drain} is specified, a flush is issued without draining the request
> +queue first.
> +
>   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
>   specified as well.
Reviewed-by: Denis V. Lunev <den@openvz.org>