block: Add support for throttling burst max in QMP and the command line.

The max parameter of the leaky bucket throttling algorithm can be used to
allow the guest to do bursts.
The max value is a pool of I/O that the guest can use without being throttled
at all. Throttling is triggered once this pool is empty.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 78 insertions, 16 deletions

diff --git a/blockdev.c b/blockdev.c
index 5f5ba968ed..76e9308e17 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -494,13 +494,18 @@ static DriveInfo *blockdev_init(QemuOpts *all_opts,
     cfg.buckets[THROTTLE_OPS_WRITE].avg =
         qemu_opt_get_number(opts, "throttling.iops-write", 0);
 
-    cfg.buckets[THROTTLE_BPS_TOTAL].max = 0;
-    cfg.buckets[THROTTLE_BPS_READ].max  = 0;
-    cfg.buckets[THROTTLE_BPS_WRITE].max = 0;
-
-    cfg.buckets[THROTTLE_OPS_TOTAL].max = 0;
-    cfg.buckets[THROTTLE_OPS_READ].max  = 0;
-    cfg.buckets[THROTTLE_OPS_WRITE].max = 0;
+    cfg.buckets[THROTTLE_BPS_TOTAL].max =
+        qemu_opt_get_number(opts, "throttling.bps-total-max", 0);
+    cfg.buckets[THROTTLE_BPS_READ].max  =
+        qemu_opt_get_number(opts, "throttling.bps-read-max", 0);
+    cfg.buckets[THROTTLE_BPS_WRITE].max =
+        qemu_opt_get_number(opts, "throttling.bps-write-max", 0);
+    cfg.buckets[THROTTLE_OPS_TOTAL].max =
+        qemu_opt_get_number(opts, "throttling.iops-total-max", 0);
+    cfg.buckets[THROTTLE_OPS_READ].max =
+        qemu_opt_get_number(opts, "throttling.iops-read-max", 0);
+    cfg.buckets[THROTTLE_OPS_WRITE].max =
+        qemu_opt_get_number(opts, "throttling.iops-write-max", 0);
 
     cfg.op_size = 0;
 
@@ -761,6 +766,14 @@ DriveInfo *drive_init(QemuOpts *all_opts, BlockInterfaceType block_default_type)
     qemu_opt_rename(all_opts, "bps_rd", "throttling.bps-read");
     qemu_opt_rename(all_opts, "bps_wr", "throttling.bps-write");
 
+    qemu_opt_rename(all_opts, "iops_max", "throttling.iops-total-max");
+    qemu_opt_rename(all_opts, "iops_rd_max", "throttling.iops-read-max");
+    qemu_opt_rename(all_opts, "iops_wr_max", "throttling.iops-write-max");
+
+    qemu_opt_rename(all_opts, "bps_max", "throttling.bps-total-max");
+    qemu_opt_rename(all_opts, "bps_rd_max", "throttling.bps-read-max");
+    qemu_opt_rename(all_opts, "bps_wr_max", "throttling.bps-write-max");
+
     qemu_opt_rename(all_opts, "readonly", "read-only");
 
     value = qemu_opt_get(all_opts, "cache");
@@ -1245,8 +1258,22 @@ void qmp_change_blockdev(const char *device, const char *filename,
 
 /* throttling disk I/O limits */
 void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
-                               int64_t bps_wr, int64_t iops, int64_t iops_rd,
-                               int64_t iops_wr, Error **errp)
+                               int64_t bps_wr,
+                               int64_t iops,
+                               int64_t iops_rd,
+                               int64_t iops_wr,
+                               bool has_bps_max,
+                               int64_t bps_max,
+                               bool has_bps_rd_max,
+                               int64_t bps_rd_max,
+                               bool has_bps_wr_max,
+                               int64_t bps_wr_max,
+                               bool has_iops_max,
+                               int64_t iops_max,
+                               bool has_iops_rd_max,
+                               int64_t iops_rd_max,
+                               bool has_iops_wr_max,
+                               int64_t iops_wr_max, Error **errp)
 {
     ThrottleConfig cfg;
     BlockDriverState *bs;
@@ -1266,13 +1293,24 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
     cfg.buckets[THROTTLE_OPS_READ].avg  = iops_rd;
     cfg.buckets[THROTTLE_OPS_WRITE].avg = iops_wr;
 
-    cfg.buckets[THROTTLE_BPS_TOTAL].max = 0;
-    cfg.buckets[THROTTLE_BPS_READ].max  = 0;
-    cfg.buckets[THROTTLE_BPS_WRITE].max = 0;
-
-    cfg.buckets[THROTTLE_OPS_TOTAL].max = 0;
-    cfg.buckets[THROTTLE_OPS_READ].max  = 0;
-    cfg.buckets[THROTTLE_OPS_WRITE].max = 0;
+    if (has_bps_max) {
+        cfg.buckets[THROTTLE_BPS_TOTAL].max = bps_max;
+    }
+    if (has_bps_rd_max) {
+        cfg.buckets[THROTTLE_BPS_READ].max = bps_rd_max;
+    }
+    if (has_bps_wr_max) {
+        cfg.buckets[THROTTLE_BPS_WRITE].max = bps_wr_max;
+    }
+    if (has_iops_max) {
+        cfg.buckets[THROTTLE_OPS_TOTAL].max = iops_max;
+    }
+    if (has_iops_rd_max) {
+        cfg.buckets[THROTTLE_OPS_READ].max = iops_rd_max;
+    }
+    if (has_iops_wr_max) {
+        cfg.buckets[THROTTLE_OPS_WRITE].max = iops_wr_max;
+    }
 
     cfg.op_size = 0;
 
@@ -1976,6 +2014,30 @@ QemuOptsList qemu_common_drive_opts = {
             .type = QEMU_OPT_NUMBER,
             .help = "limit write bytes per second",
         },{
+            .name = "throttling.iops-total-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "I/O operations burst",
+        },{
+            .name = "throttling.iops-read-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "I/O operations read burst",
+        },{
+            .name = "throttling.iops-write-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "I/O operations write burst",
+        },{
+            .name = "throttling.bps-total-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "total bytes burst",
+        },{
+            .name = "throttling.bps-read-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "total bytes read burst",
+        },{
+            .name = "throttling.bps-write-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "total bytes write burst",
+        },{
             .name = "copy-on-read",
             .type = QEMU_OPT_BOOL,
             .help = "copy read data from backing file into image file",