Block Throttle Group Support

index f2f8ae7..28508ef 100644
@@ -130,7 +130,7 @@ void bdrv_set_io_limits(BlockDriverState *bs,
 {
     int i;
 
-    throttle_config(&bs->throttle_state, cfg);
+    throttle_config(&bs->throttle_state, &bs->throttle_timers, cfg);
 
     for (i = 0; i < 2; i++) {
         qemu_co_enter_next(&bs->throttled_reqs[i]);

@@ -163,7 +163,7 @@ void bdrv_io_limits_disable(BlockDriverState *bs)
 
     bdrv_start_throttled_reqs(bs);
 
-    throttle_destroy(&bs->throttle_state);
+    throttle_timers_destroy(&bs->throttle_timers);
 }
 
 static void bdrv_throttle_read_timer_cb(void *opaque)

@@ -182,12 +182,13 @@ static void bdrv_throttle_write_timer_cb(void *opaque)
 void bdrv_io_limits_enable(BlockDriverState *bs)
 {
     assert(!bs->io_limits_enabled);
-    throttle_init(&bs->throttle_state,
-                  bdrv_get_aio_context(bs),
-                  QEMU_CLOCK_VIRTUAL,
-                  bdrv_throttle_read_timer_cb,
-                  bdrv_throttle_write_timer_cb,
-                  bs);
+    throttle_init(&bs->throttle_state);
+    throttle_timers_init(&bs->throttle_timers,
+                         bdrv_get_aio_context(bs),
+                         QEMU_CLOCK_VIRTUAL,
+                         bdrv_throttle_read_timer_cb,
+                         bdrv_throttle_write_timer_cb,
+                         bs);
     bs->io_limits_enabled = true;
 }
 

@@ -201,7 +202,9 @@ static void bdrv_io_limits_intercept(BlockDriverState *bs,
                                      bool is_write)
 {
     /* does this io must wait */
-    bool must_wait = throttle_schedule_timer(&bs->throttle_state, is_write);
+    bool must_wait = throttle_schedule_timer(&bs->throttle_state,
+                                             &bs->throttle_timers,
+                                             is_write);
 
     /* if must wait or any request of this type throttled queue the IO */
     if (must_wait ||

@@ -214,7 +217,8 @@ static void bdrv_io_limits_intercept(BlockDriverState *bs,
 
 
     /* if the next request must wait -> do nothing */
-    if (throttle_schedule_timer(&bs->throttle_state, is_write)) {
+    if (throttle_schedule_timer(&bs->throttle_state, &bs->throttle_timers,
+                                is_write)) {
         return;
     }
 

@@ -2090,6 +2094,9 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
     memcpy(&bs_dest->throttle_state,
            &bs_src->throttle_state,
            sizeof(ThrottleState));
+    memcpy(&bs_dest->throttle_timers,
+           &bs_src->throttle_timers,
+           sizeof(ThrottleTimers));
     bs_dest->throttled_reqs[0]  = bs_src->throttled_reqs[0];
     bs_dest->throttled_reqs[1]  = bs_src->throttled_reqs[1];
     bs_dest->io_limits_enabled  = bs_src->io_limits_enabled;

@@ -2151,7 +2158,7 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
     assert(bs_new->job == NULL);
     assert(bs_new->io_limits_enabled == false);
-    assert(!throttle_have_timer(&bs_new->throttle_state));
+    assert(!throttle_timers_are_initialized(&bs_new->throttle_timers));
 
     tmp = *bs_new;
     *bs_new = *bs_old;

@@ -2168,7 +2175,7 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     /* Check a few fields that should remain attached to the device */
     assert(bs_new->job == NULL);
     assert(bs_new->io_limits_enabled == false);
-    assert(!throttle_have_timer(&bs_new->throttle_state));
+    assert(!throttle_timers_are_initialized(&bs_new->throttle_timers));
 
     /* insert the nodes back into the graph node list if needed */
     if (bs_new->node_name[0] != '\0') {

@@ -5858,7 +5865,7 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
     }
 
     if (bs->io_limits_enabled) {
-        throttle_detach_aio_context(&bs->throttle_state);
+        throttle_timers_detach_aio_context(&bs->throttle_timers);
     }
     if (bs->drv->bdrv_detach_aio_context) {
         bs->drv->bdrv_detach_aio_context(bs);

@@ -5894,7 +5901,7 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
         bs->drv->bdrv_attach_aio_context(bs, new_context);
     }
     if (bs->io_limits_enabled) {
-        throttle_attach_aio_context(&bs->throttle_state, new_context);
+        throttle_timers_attach_aio_context(&bs->throttle_timers, new_context);
     }
 
     QLIST_FOREACH(ban, &bs->aio_notifiers, list) {

index dccb092..c88a062 100644
@@ -377,6 +377,7 @@ struct BlockDriverState {
 
     /* I/O throttling */
     ThrottleState throttle_state;
+    ThrottleTimers throttle_timers;
     CoQueue      throttled_reqs[2];
     bool         io_limits_enabled;
 

index b890613..2c560db 100644
@@ -65,14 +65,17 @@ typedef struct ThrottleConfig {
 typedef struct ThrottleState {
     ThrottleConfig cfg;       /* configuration */
     int64_t previous_leak;    /* timestamp of the last leak done */
-    QEMUTimer * timers[2];    /* timers used to do the throttling */
+} ThrottleState;
+
+typedef struct ThrottleTimers {
+    QEMUTimer *timers[2];     /* timers used to do the throttling */
     QEMUClockType clock_type; /* the clock used */
 
     /* Callbacks */
     QEMUTimerCB *read_timer_cb;
     QEMUTimerCB *write_timer_cb;
     void *timer_opaque;
-} ThrottleState;
+} ThrottleTimers;
 
 /* operations on single leaky buckets */
 void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta);

@@ -86,20 +89,23 @@ bool throttle_compute_timer(ThrottleState *ts,
                             int64_t *next_timestamp);
 
 /* init/destroy cycle */
-void throttle_init(ThrottleState *ts,
-                   AioContext *aio_context,
-                   QEMUClockType clock_type,
-                   void (read_timer)(void *),
-                   void (write_timer)(void *),
-                   void *timer_opaque);
+void throttle_init(ThrottleState *ts);
+
+void throttle_timers_init(ThrottleTimers *tt,
+                          AioContext *aio_context,
+                          QEMUClockType clock_type,
+                          QEMUTimerCB *read_timer_cb,
+                          QEMUTimerCB *write_timer_cb,
+                          void *timer_opaque);
 
-void throttle_destroy(ThrottleState *ts);
+void throttle_timers_destroy(ThrottleTimers *tt);
 
-void throttle_detach_aio_context(ThrottleState *ts);
+void throttle_timers_detach_aio_context(ThrottleTimers *tt);
 
-void throttle_attach_aio_context(ThrottleState *ts, AioContext *new_context);
+void throttle_timers_attach_aio_context(ThrottleTimers *tt,
+                                        AioContext *new_context);
 
-bool throttle_have_timer(ThrottleState *ts);
+bool throttle_timers_are_initialized(ThrottleTimers *tt);
 
 /* configuration */
 bool throttle_enabled(ThrottleConfig *cfg);

@@ -108,12 +114,16 @@ bool throttle_conflicting(ThrottleConfig *cfg);
 
 bool throttle_is_valid(ThrottleConfig *cfg);
 
-void throttle_config(ThrottleState *ts, ThrottleConfig *cfg);
+void throttle_config(ThrottleState *ts,
+                     ThrottleTimers *tt,
+                     ThrottleConfig *cfg);
 
 void throttle_get_config(ThrottleState *ts, ThrottleConfig *cfg);
 
 /* usage */
-bool throttle_schedule_timer(ThrottleState *ts, bool is_write);
+bool throttle_schedule_timer(ThrottleState *ts,
+                             ThrottleTimers *tt,
+                             bool is_write);
 
 void throttle_account(ThrottleState *ts, bool is_write, uint64_t size);
 

163 lines not on this page · raw message

140 lines not on this page · raw message

261 lines not on this page · raw message

index c88a062..f0896e9 100644
@@ -380,6 +380,7 @@ struct BlockDriverState {
     ThrottleTimers throttle_timers;
     CoQueue      throttled_reqs[2];
     bool         io_limits_enabled;
+    QLIST_ENTRY(BlockDriverState) round_robin;
 
     /* I/O stats (display with "info blockstats"). */
     BlockAcctStats stats;

new file mode 100644
index 0000000..b966ec7
@@ -0,0 +1,39 @@
+/*
+ * QEMU block throttling group infrastructure
+ *
+ * Copyright (C) Nodalink, EURL. 2014
+ * Copyright (C) Igalia, S.L. 2015
+ *
+ * Authors:
+ *   Benoît Canet <[email protected]>
+ *   Alberto Garcia <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 or
+ * (at your option) version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef THROTTLE_GROUPS_H
+#define THROTTLE_GROUPS_H
+
+#include "qemu/throttle.h"
+#include "block/block_int.h"
+
+const char *throttle_group_get_name(BlockDriverState *bs);
+
+void throttle_group_config(BlockDriverState *bs, ThrottleConfig *cfg);
+void throttle_group_get_config(BlockDriverState *bs, ThrottleConfig *cfg);
+
+void throttle_group_register_bs(BlockDriverState *bs, const char *groupname);
+void throttle_group_unregister_bs(BlockDriverState *bs);
+
+#endif

index 458f577..aa0e297 100644
@@ -1,10 +1,12 @@
 /*
  * Throttle infrastructure tests
  *
- * Copyright Nodalink, SARL. 2013
+ * Copyright Nodalink, EURL. 2013-2014
+ * Copyright Igalia, S.L. 2015
  *
  * Authors:
- *  Benoît Canet     <[email protected]>
+ *  Benoît Canet     <[email protected]>
+ *  Alberto Garcia   <[email protected]>
  *
  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
  * See the COPYING.LIB file in the top-level directory.

@@ -15,6 +17,7 @@
 #include "block/aio.h"
 #include "qemu/throttle.h"
 #include "qemu/error-report.h"
+#include "block/throttle-groups.h"
 
 static AioContext     *ctx;
 static LeakyBucket    bkt;

@@ -500,23 +503,78 @@ static void test_accounting(void)
                                 (64.0 / 13)));
 }
 
+static void test_groups(void)
+{
+    ThrottleConfig cfg1, cfg2;
+    BlockDriverState *bdrv1, *bdrv2, *bdrv3;
+
+    bdrv1 = bdrv_new();
+    bdrv2 = bdrv_new();
+    bdrv3 = bdrv_new();
+
+    g_assert(bdrv1->throttle_state == NULL);
+    g_assert(bdrv2->throttle_state == NULL);
+    g_assert(bdrv3->throttle_state == NULL);
+
+    throttle_group_register_bs(bdrv1, "bar");
+    throttle_group_register_bs(bdrv2, "foo");
+    throttle_group_register_bs(bdrv3, "bar");
+
+    g_assert(bdrv1->throttle_state != NULL);
+    g_assert(bdrv2->throttle_state != NULL);
+    g_assert(bdrv3->throttle_state != NULL);
+
+    g_assert(!strcmp(throttle_group_get_name(bdrv1), "bar"));
+    g_assert(!strcmp(throttle_group_get_name(bdrv2), "foo"));
+    g_assert(bdrv1->throttle_state == bdrv3->throttle_state);
+
+    /* Setting the config of a group member affects the whole group */
+    memset(&cfg1, 0, sizeof(cfg1));
+    cfg1.buckets[THROTTLE_BPS_READ].avg  = 500000;
+    cfg1.buckets[THROTTLE_BPS_WRITE].avg = 285000;
+    cfg1.buckets[THROTTLE_OPS_READ].avg  = 20000;
+    cfg1.buckets[THROTTLE_OPS_WRITE].avg = 12000;
+    throttle_group_config(bdrv1, &cfg1);
+
+    throttle_group_get_config(bdrv1, &cfg1);
+    throttle_group_get_config(bdrv3, &cfg2);
+    g_assert(!memcmp(&cfg1, &cfg2, sizeof(cfg1)));
+
+    cfg2.buckets[THROTTLE_BPS_READ].avg  = 4547;
+    cfg2.buckets[THROTTLE_BPS_WRITE].avg = 1349;
+    cfg2.buckets[THROTTLE_OPS_READ].avg  = 123;
+    cfg2.buckets[THROTTLE_OPS_WRITE].avg = 86;
+    throttle_group_config(bdrv3, &cfg1);
+
+    throttle_group_get_config(bdrv1, &cfg1);
+    throttle_group_get_config(bdrv3, &cfg2);
+    g_assert(!memcmp(&cfg1, &cfg2, sizeof(cfg1)));
+
+    throttle_group_unregister_bs(bdrv1);
+    throttle_group_unregister_bs(bdrv2);
+    throttle_group_unregister_bs(bdrv3);
+
+    g_assert(bdrv1->throttle_state == NULL);
+    g_assert(bdrv2->throttle_state == NULL);
+    g_assert(bdrv3->throttle_state == NULL);
+}
+
 int main(int argc, char **argv)
 {
-    GSource *src;
     Error *local_error = NULL;
 
-    init_clocks();
+    qemu_init_main_loop(&local_error);
+    ctx = qemu_get_aio_context();
 
-    ctx = aio_context_new(&local_error);
     if (!ctx) {
         error_report("Failed to create AIO Context: '%s'",
-                     error_get_pretty(local_error));
-        error_free(local_error);
+                     local_error ? error_get_pretty(local_error) :
+                     "Failed to initialize the QEMU main loop");
+        if (local_error) {
+            error_free(local_error);
+        }
         exit(1);
     }
-    src = aio_get_g_source(ctx);
-    g_source_attach(src, NULL);
-    g_source_unref(src);
 
     do {} while (g_main_context_iteration(NULL, false));
 

@@ -533,6 +591,7 @@ int main(int argc, char **argv)
     g_test_add_func("/throttle/config/is_valid",    test_is_valid);
     g_test_add_func("/throttle/config_functions",   test_config_functions);
     g_test_add_func("/throttle/accounting",         test_accounting);
+    g_test_add_func("/throttle/groups",             test_groups);
     return g_test_run();
 }
 

index 28508ef..5ca972f 100644
@@ -36,6 +36,7 @@
 #include "qmp-commands.h"
 #include "qemu/timer.h"
 #include "qapi-event.h"
+#include "block/throttle-groups.h"
 
 #ifdef CONFIG_BSD
 #include <sys/types.h>

@@ -130,7 +131,7 @@ void bdrv_set_io_limits(BlockDriverState *bs,
 {
     int i;
 
-    throttle_config(&bs->throttle_state, &bs->throttle_timers, cfg);
+    throttle_group_config(bs, cfg);
 
     for (i = 0; i < 2; i++) {
         qemu_co_enter_next(&bs->throttled_reqs[i]);

@@ -160,70 +161,33 @@ static bool bdrv_start_throttled_reqs(BlockDriverState *bs)
 void bdrv_io_limits_disable(BlockDriverState *bs)
 {
     bs->io_limits_enabled = false;
-
     bdrv_start_throttled_reqs(bs);
-
-    throttle_timers_destroy(&bs->throttle_timers);
-}
-
-static void bdrv_throttle_read_timer_cb(void *opaque)
-{
-    BlockDriverState *bs = opaque;
-    qemu_co_enter_next(&bs->throttled_reqs[0]);
-}
-
-static void bdrv_throttle_write_timer_cb(void *opaque)
-{
-    BlockDriverState *bs = opaque;
-    qemu_co_enter_next(&bs->throttled_reqs[1]);
+    throttle_group_unregister_bs(bs);
 }
 
 /* should be called before bdrv_set_io_limits if a limit is set */
-void bdrv_io_limits_enable(BlockDriverState *bs)
+void bdrv_io_limits_enable(BlockDriverState *bs, const char *group)
 {
     assert(!bs->io_limits_enabled);
-    throttle_init(&bs->throttle_state);
-    throttle_timers_init(&bs->throttle_timers,
-                         bdrv_get_aio_context(bs),
-                         QEMU_CLOCK_VIRTUAL,
-                         bdrv_throttle_read_timer_cb,
-                         bdrv_throttle_write_timer_cb,
-                         bs);
+    throttle_group_register_bs(bs, group);
     bs->io_limits_enabled = true;
 }
 
-/* This function makes an IO wait if needed
- *
- * @nb_sectors: the number of sectors of the IO
- * @is_write:   is the IO a write
- */
-static void bdrv_io_limits_intercept(BlockDriverState *bs,
-                                     unsigned int bytes,
-                                     bool is_write)
+void bdrv_io_limits_update_group(BlockDriverState *bs, const char *group)
 {
-    /* does this io must wait */
-    bool must_wait = throttle_schedule_timer(&bs->throttle_state,
-                                             &bs->throttle_timers,
-                                             is_write);
-
-    /* if must wait or any request of this type throttled queue the IO */
-    if (must_wait ||
-        !qemu_co_queue_empty(&bs->throttled_reqs[is_write])) {
-        qemu_co_queue_wait(&bs->throttled_reqs[is_write]);
+    /* this bs is not part of any group */
+    if (!bs->throttle_state) {
+        return;
     }
 
-    /* the IO will be executed, do the accounting */
-    throttle_account(&bs->throttle_state, is_write, bytes);
-
-
-    /* if the next request must wait -> do nothing */
-    if (throttle_schedule_timer(&bs->throttle_state, &bs->throttle_timers,
-                                is_write)) {
+    /* this bs is a part of the same group than the one we want */
+    if (!g_strcmp0(throttle_group_get_name(bs), group)) {
         return;
     }
 
-    /* else queue next request for execution */
-    qemu_co_queue_next(&bs->throttled_reqs[is_write]);
+    /* need to change the group this bs belong to */
+    bdrv_io_limits_disable(bs);
+    bdrv_io_limits_enable(bs, group);
 }
 
 size_t bdrv_opt_mem_align(BlockDriverState *bs)

@@ -2091,15 +2055,18 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
     bs_dest->enable_write_cache = bs_src->enable_write_cache;
 
     /* i/o throttled req */
-    memcpy(&bs_dest->throttle_state,
-           &bs_src->throttle_state,
-           sizeof(ThrottleState));
+    bs_dest->throttle_state     = bs_src->throttle_state,
+    bs_dest->io_limits_enabled  = bs_src->io_limits_enabled;
+    bs_dest->pending_reqs[0]    = bs_src->pending_reqs[0];
+    bs_dest->pending_reqs[1]    = bs_src->pending_reqs[1];
+    bs_dest->throttled_reqs[0]  = bs_src->throttled_reqs[0];
+    bs_dest->throttled_reqs[1]  = bs_src->throttled_reqs[1];
+    memcpy(&bs_dest->round_robin,
+           &bs_src->round_robin,
+           sizeof(bs_dest->round_robin));
     memcpy(&bs_dest->throttle_timers,
            &bs_src->throttle_timers,
            sizeof(ThrottleTimers));
-    bs_dest->throttled_reqs[0]  = bs_src->throttled_reqs[0];
-    bs_dest->throttled_reqs[1]  = bs_src->throttled_reqs[1];
-    bs_dest->io_limits_enabled  = bs_src->io_limits_enabled;
 
     /* r/w error */
     bs_dest->on_read_error      = bs_src->on_read_error;

@@ -3170,7 +3137,7 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
 
     /* throttling disk I/O */
     if (bs->io_limits_enabled) {
-        bdrv_io_limits_intercept(bs, bytes, false);
+        throttle_group_co_io_limits_intercept(bs, bytes, false);
     }
 
     /* Align read if necessary by padding qiov */

@@ -3411,7 +3378,7 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
 
     /* throttling disk I/O */
     if (bs->io_limits_enabled) {
-        bdrv_io_limits_intercept(bs, bytes, true);
+        throttle_group_co_io_limits_intercept(bs, bytes, true);
     }
 
     /*

index 8a19aed..65af057 100644
@@ -24,6 +24,7 @@
 
 #include "block/qapi.h"
 #include "block/block_int.h"
+#include "block/throttle-groups.h"
 #include "block/write-threshold.h"
 #include "qmp-commands.h"
 #include "qapi-visit.h"

@@ -63,7 +64,9 @@ BlockDeviceInfo *bdrv_block_device_info(BlockDriverState *bs)
 
     if (bs->io_limits_enabled) {
         ThrottleConfig cfg;
-        throttle_get_config(&bs->throttle_state, &cfg);
+
+        throttle_group_get_config(bs, &cfg);
+
         info->bps     = cfg.buckets[THROTTLE_BPS_TOTAL].avg;
         info->bps_rd  = cfg.buckets[THROTTLE_BPS_READ].avg;
         info->bps_wr  = cfg.buckets[THROTTLE_BPS_WRITE].avg;

241 lines not on this page · raw message

index fbb3a79..98ef26f 100644
@@ -357,6 +357,7 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
     const char *id;
     bool has_driver_specific_opts;
     BlockdevDetectZeroesOptions detect_zeroes;
+    const char *throttling_group;
 
     /* Check common options by copying from bs_opts to opts, all other options
      * stay in bs_opts for processing by bdrv_open(). */

@@ -459,6 +460,8 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
 
     cfg.op_size = qemu_opt_get_number(opts, "throttling.iops-size", 0);
 
+    throttling_group = qemu_opt_get(opts, "throttling.group");
+
     if (!check_throttle_config(&cfg, &error)) {
         error_propagate(errp, error);
         goto early_err;

@@ -547,7 +550,10 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
 
     /* disk I/O throttling */
     if (throttle_enabled(&cfg)) {
-        bdrv_io_limits_enable(bs);
+        if (!throttling_group) {
+            throttling_group = blk_name(blk);
+        }
+        bdrv_io_limits_enable(bs, throttling_group);
         bdrv_set_io_limits(bs, &cfg);
     }
 

@@ -711,6 +717,8 @@ DriveInfo *drive_new(QemuOpts *all_opts, BlockInterfaceType block_default_type)
 
         { "iops_size",      "throttling.iops-size" },
 
+        { "group",          "throttling.group" },
+
         { "readonly",       "read-only" },
     };
 

@@ -1887,7 +1895,9 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
                                bool has_iops_wr_max,
                                int64_t iops_wr_max,
                                bool has_iops_size,
-                               int64_t iops_size, Error **errp)
+                               int64_t iops_size,
+                               bool has_group,
+                               const char *group, Error **errp)
 {
     ThrottleConfig cfg;
     BlockDriverState *bs;

@@ -1941,9 +1951,11 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
     aio_context_acquire(aio_context);
 
     if (!bs->io_limits_enabled && throttle_enabled(&cfg)) {
-        bdrv_io_limits_enable(bs);
+        bdrv_io_limits_enable(bs, has_group ? group : device);
     } else if (bs->io_limits_enabled && !throttle_enabled(&cfg)) {
         bdrv_io_limits_disable(bs);
+    } else if (bs->io_limits_enabled && throttle_enabled(&cfg)) {
+        bdrv_io_limits_update_group(bs, has_group ? group : device);
     }
 
     if (bs->io_limits_enabled) {

@@ -3017,6 +3029,10 @@ QemuOptsList qemu_common_drive_opts = {
             .type = QEMU_OPT_NUMBER,
             .help = "when limiting by iops max size of an I/O in bytes",
         },{
+            .name = "throttling.group",
+            .type = QEMU_OPT_STRING,
+            .help = "name of the block throttling group",
+        },{
             .name = "copy-on-read",
             .type = QEMU_OPT_BOOL,
             .help = "copy read data from backing file into image file",

index f31ae27..50f30f2 100644
@@ -1272,7 +1272,9 @@ void hmp_block_set_io_throttle(Monitor *mon, const QDict *qdict)
                               false,
                               0,
                               false, /* No default I/O size */
-                              0, &err);
+                              0,
+                              false,
+                              NULL, &err);
     hmp_handle_error(mon, &err);
 }
 

index 4c57d63..e0d53f3 100644
@@ -173,8 +173,9 @@ void bdrv_stats_print(Monitor *mon, const QObject *data);
 void bdrv_info_stats(Monitor *mon, QObject **ret_data);
 
 /* disk I/O throttling */
-void bdrv_io_limits_enable(BlockDriverState *bs);
+void bdrv_io_limits_enable(BlockDriverState *bs, const char *group);
 void bdrv_io_limits_disable(BlockDriverState *bs);
+void bdrv_io_limits_update_group(BlockDriverState *bs, const char *group);
 
 void bdrv_init(void);
 void bdrv_init_with_whitelist(void);

index f0896e9..4e09825 100644
@@ -376,10 +376,13 @@ struct BlockDriverState {
     unsigned int serialising_in_flight;
 
     /* I/O throttling */
-    ThrottleState throttle_state;
-    ThrottleTimers throttle_timers;
     CoQueue      throttled_reqs[2];
     bool         io_limits_enabled;
+    /* The following fields are protected by the ThrottleGroup lock.
+     * See the ThrottleGroup documentation for details. */
+    ThrottleState *throttle_state;
+    ThrottleTimers throttle_timers;
+    unsigned       pending_reqs[2];
     QLIST_ENTRY(BlockDriverState) round_robin;
 
     /* I/O stats (display with "info blockstats"). */

index b966ec7..322139a 100644
@@ -36,4 +36,8 @@ void throttle_group_get_config(BlockDriverState *bs, ThrottleConfig *cfg);
 void throttle_group_register_bs(BlockDriverState *bs, const char *groupname);
 void throttle_group_unregister_bs(BlockDriverState *bs);
 
+void coroutine_fn throttle_group_co_io_limits_intercept(BlockDriverState *bs,
+                                                        unsigned int bytes,
+                                                        bool is_write);
+
 #endif

index 5ca972f..5643082 100644
@@ -2120,11 +2120,20 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
         QTAILQ_REMOVE(&graph_bdrv_states, bs_old, node_list);
     }
 
+    /* If the BlockDriverState is part of a throttling group acquire
+     * its lock since we're going to mess with the protected fields.
+     * Otherwise there's no need to worry since no one else can touch
+     * them. */
+    if (bs_old->throttle_state) {
+        throttle_group_lock(bs_old);
+    }
+
     /* bs_new must be unattached and shouldn't have anything fancy enabled */
     assert(!bs_new->blk);
     assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
     assert(bs_new->job == NULL);
     assert(bs_new->io_limits_enabled == false);
+    assert(bs_new->throttle_state == NULL);
     assert(!throttle_timers_are_initialized(&bs_new->throttle_timers));
 
     tmp = *bs_new;

@@ -2142,8 +2151,14 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
     /* Check a few fields that should remain attached to the device */
     assert(bs_new->job == NULL);
     assert(bs_new->io_limits_enabled == false);
+    assert(bs_new->throttle_state == NULL);
     assert(!throttle_timers_are_initialized(&bs_new->throttle_timers));
 
+    /* Release the ThrottleGroup lock */
+    if (bs_old->throttle_state) {
+        throttle_group_unlock(bs_old);
+    }
+
     /* insert the nodes back into the graph node list if needed */
     if (bs_new->node_name[0] != '\0') {
         QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs_new, node_list);

index f909f50..20a510a 100644
@@ -32,7 +32,8 @@
  * its own locking.
  *
  * This locking is however handled internally in this file, so it's
- * transparent to outside users.
+ * mostly transparent to outside users (but see the documentation in
+ * throttle_groups_lock()).
  *
  * The whole ThrottleGroup structure is private and invisible to
  * outside users, that only use it through its ThrottleState.

@@ -452,6 +453,34 @@ void throttle_group_unregister_bs(BlockDriverState *bs)
     bs->throttle_state = NULL;
 }
 
+/* Acquire the lock of this throttling group.
+ *
+ * You won't normally need to use this. None of the functions from the
+ * ThrottleGroup API require you to acquire the lock since all of them
+ * deal with it internally.
+ *
+ * This should only be used in exceptional cases when you want to
+ * access the protected fields of a BlockDriverState directly
+ * (e.g. bdrv_swap()).
+ *
+ * @bs: a BlockDriverState that is member of the group
+ */
+void throttle_group_lock(BlockDriverState *bs)
+{
+    ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
+    qemu_mutex_lock(&tg->lock);
+}
+
+/* Release the lock of this throttling group.
+ *
+ * See the comments in throttle_group_lock().
+ */
+void throttle_group_unlock(BlockDriverState *bs)
+{
+    ThrottleGroup *tg = container_of(bs->throttle_state, ThrottleGroup, ts);
+    qemu_mutex_unlock(&tg->lock);
+}
+
 static void throttle_groups_init(void)
 {
     qemu_mutex_init(&throttle_groups_lock);

index 322139a..fab113f 100644
@@ -40,4 +40,7 @@ void coroutine_fn throttle_group_co_io_limits_intercept(BlockDriverState *bs,
                                                         unsigned int bytes,
                                                         bool is_write);
 
+void throttle_group_lock(BlockDriverState *bs);
+void throttle_group_unlock(BlockDriverState *bs);
+
 #endif

index 65af057..ee823d1 100644
@@ -91,6 +91,9 @@ BlockDeviceInfo *bdrv_block_device_info(BlockDriverState *bs)
 
         info->has_iops_size = cfg.op_size;
         info->iops_size = cfg.op_size;
+
+        info->has_group = true;
+        info->group = g_strdup(throttle_group_get_name(bs));
     }
 
     info->write_threshold = bdrv_write_threshold_get(bs);

index 50f30f2..759fb86 100644
@@ -375,7 +375,8 @@ static void print_block_info(Monitor *mon, BlockInfo *info,
                         " iops_max=%" PRId64
                         " iops_rd_max=%" PRId64
                         " iops_wr_max=%" PRId64
-                        " iops_size=%" PRId64 "\n",
+                        " iops_size=%" PRId64
+                        " group=%s\n",
                         inserted->bps,
                         inserted->bps_rd,
                         inserted->bps_wr,

@@ -388,7 +389,8 @@ static void print_block_info(Monitor *mon, BlockInfo *info,
                         inserted->iops_max,
                         inserted->iops_rd_max,
                         inserted->iops_wr_max,
-                        inserted->iops_size);
+                        inserted->iops_size,
+                        inserted->group);
     }
 
     if (verbose) {

index 2c560db..5af76f0 100644
@@ -1,10 +1,12 @@
 /*
  * QEMU throttling infrastructure
  *
- * Copyright (C) Nodalink, SARL. 2013
+ * Copyright (C) Nodalink, EURL. 2013-2014
+ * Copyright (C) Igalia, S.L. 2015
  *
- * Author:
- *   Benoît Canet <[email protected]>
+ * Authors:
+ *   Benoît Canet <[email protected]>
+ *   Alberto Garcia <[email protected]>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as

index d76a48e..706c131 100644
@@ -1,10 +1,12 @@
 /*
  * QEMU throttling infrastructure
  *
- * Copyright (C) Nodalink, SARL. 2013
+ * Copyright (C) Nodalink, EURL. 2013-2014
+ * Copyright (C) Igalia, S.L. 2015
  *
- * Author:
- *   Benoît Canet <[email protected]>
+ * Authors:
+ *   Benoît Canet <[email protected]>
+ *   Alberto Garcia <[email protected]>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as