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

[Kevin Wolf <kwolf@redhat.com>]

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       | 69 ++++++++++++++++++++++++++++++++++++++++++++++++--------
 qemu-img.texi    |  6 ++++-
 3 files changed, 67 insertions(+), 12 deletions(-)

diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index f5d0098..04d70d4 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] [-S step_size] [-t cache] [-w] filename")
+    "bench [-c count] [-d depth] [-f fmt] [--flush-interval=flush_interval] [-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}] [-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] [-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 ff99181..76904db 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -53,6 +53,7 @@ enum {
     OPTION_BACKING_CHAIN = 257,
     OPTION_OBJECT = 258,
     OPTION_IMAGE_OPTS = 259,
+    OPTION_FLUSH_INTERVAL = 260,
 };
 
 typedef enum OutputFormat {
@@ -3467,10 +3468,12 @@ typedef struct BenchData {
     int step;
     int nrreq;
     int n;
+    int flush_interval;
     uint8_t *buf;
     QEMUIOVector *qiov;
 
     int in_flight;
+    bool in_flush;
     uint64_t offset;
 } BenchData;
 
@@ -3483,9 +3486,29 @@ 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: 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, then flush */
+        if (b->flush_interval && remaining % b->flush_interval == 0) {
+            if (!b->in_flight) {
+                acb = blk_aio_flush(b->blk, bench_cb, b);
+                if (!acb) {
+                    error_report("Failed to issue flush request");
+                    exit(EXIT_FAILURE);
+                }
+                b->in_flush = true;
+            }
+            return;
+        }
     }
 
     while (b->n > b->in_flight && b->in_flight < b->nrreq) {
@@ -3518,6 +3541,7 @@ static int img_bench(int argc, char **argv)
     int64_t offset = 0;
     size_t bufsize = 4096;
     size_t step = 0;
+    int flush_interval = 0;
     int64_t image_size;
     BlockBackend *blk = NULL;
     BenchData data = {};
@@ -3529,6 +3553,7 @@ 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},
             {0, 0, 0, 0}
         };
@@ -3626,6 +3651,17 @@ static int img_bench(int argc, char **argv)
             flags |= BDRV_O_RDWR;
             is_write = true;
             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_IMAGE_OPTS:
             image_opts = true;
             break;
@@ -3637,6 +3673,17 @@ 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;
@@ -3650,19 +3697,23 @@ 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,
     };
     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, 0, data.nrreq * data.bufsize);
diff --git a/qemu-img.texi b/qemu-img.texi
index 6b03d3f..270fb4c 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}] [-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] [-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.
@@ -142,6 +142,10 @@ 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 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 @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.
-- 
1.8.3.1