[Qemu-devel] [PATCH v11 5/6] fsdev: QMP interface for throttling

[Pradeep Jagadeesh]

This patch introduces qmp interfaces for the fsdev
devices. This provides two interfaces one
for querying info of all the fsdev devices. The second one
to set the IO limits for the required fsdev device.

Signed-off-by: Pradeep Jagadeesh <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
---
 Makefile                    |  3 +-
 fsdev/qemu-fsdev-dummy.c    | 11 ++++++
 fsdev/qemu-fsdev-throttle.c | 96 ++++++++++++++++++++++++++++++++++++++++++---
 fsdev/qemu-fsdev-throttle.h |  9 ++++-
 fsdev/qemu-fsdev.c          | 30 ++++++++++++++
 monitor.c                   |  5 +++
 qapi-schema.json            |  4 ++
 qapi/fsdev.json             | 81 ++++++++++++++++++++++++++++++++++++++
 qmp.c                       | 14 +++++++
 9 files changed, 244 insertions(+), 9 deletions(-)
 create mode 100644 qapi/fsdev.json

diff --git a/Makefile b/Makefile
index 337a1f6..6556dbf 100644
--- a/Makefile
+++ b/Makefile
@@ -421,7 +421,8 @@ qapi-modules = $(SRC_PATH)/qapi-schema.json 
$(SRC_PATH)/qapi/common.json \
                $(SRC_PATH)/qapi/tpm.json \
                $(SRC_PATH)/qapi/trace.json \
                $(SRC_PATH)/qapi/transaction.json \
-               $(SRC_PATH)/qapi/ui.json
+               $(SRC_PATH)/qapi/ui.json \
+                    $(SRC_PATH)/qapi/fsdev.json
 
 qapi-types.c qapi-types.h :\
 $(qapi-modules) $(SRC_PATH)/scripts/qapi-types.py $(qapi-py)
diff --git a/fsdev/qemu-fsdev-dummy.c b/fsdev/qemu-fsdev-dummy.c
index 6dc0fbc..dc5cb6c 100644
--- a/fsdev/qemu-fsdev-dummy.c
+++ b/fsdev/qemu-fsdev-dummy.c
@@ -14,8 +14,19 @@
 #include "qemu-fsdev.h"
 #include "qemu/config-file.h"
 #include "qemu/module.h"
+#include "qmp-commands.h"
 
 int qemu_fsdev_add(QemuOpts *opts)
 {
     return 0;
 }
+
+void qmp_fsdev_set_io_throttle(ThrottleLimits *arg, Error **errp)
+{
+    return;
+}
+
+ThrottleLimitsList *qmp_query_fsdev_io_throttle(Error **errp)
+{
+    return NULL;
+}
diff --git a/fsdev/qemu-fsdev-throttle.c b/fsdev/qemu-fsdev-throttle.c
index 0e6fb86..fb7a6fa 100644
--- a/fsdev/qemu-fsdev-throttle.c
+++ b/fsdev/qemu-fsdev-throttle.c
@@ -16,6 +16,7 @@
 #include "qemu/error-report.h"
 #include "qemu-fsdev-throttle.h"
 #include "qemu/iov.h"
+#include "qemu/main-loop.h"
 #include "qemu/throttle-options.h"
 
 static void fsdev_throttle_read_timer_cb(void *opaque)
@@ -30,6 +31,92 @@ static void fsdev_throttle_write_timer_cb(void *opaque)
     qemu_co_enter_next(&fst->throttled_reqs[true]);
 }
 
+typedef struct {
+    FsThrottle *fst;
+    bool is_write;
+} RestartData;
+
+static bool coroutine_fn throttle_co_restart_queue(FsThrottle *fst,
+                                                   bool is_write)
+{
+    return qemu_co_queue_next(&fst->throttled_reqs[is_write]);
+}
+
+static void schedule_next_request(FsThrottle *fst, bool is_write)
+{
+    bool must_wait = throttle_schedule_timer(&fst->ts, &fst->tt, is_write);
+    if (!must_wait) {
+        if (qemu_in_coroutine() &&
+            throttle_co_restart_queue(fst, is_write)) {
+            return;
+        } else {
+            int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
+            timer_mod(fst->tt.timers[is_write], now);
+        }
+    }
+}
+
+static void coroutine_fn throttle_restart_queue_entry(void *opaque)
+{
+    RestartData *data = opaque;
+    bool is_write = data->is_write;
+    bool empty_queue = !throttle_co_restart_queue(data->fst, is_write);
+    if (empty_queue) {
+        schedule_next_request(data->fst, is_write);
+    }
+}
+
+static void throttle_restart_queues(FsThrottle *fst)
+{
+    Coroutine *co;
+    RestartData rd = {
+        .fst = fst,
+        .is_write = true
+    };
+
+    co = qemu_coroutine_create(throttle_restart_queue_entry, &rd);
+    aio_co_enter(fst->ctx, co);
+
+    rd.is_write = false;
+
+    co = qemu_coroutine_create(throttle_restart_queue_entry, &rd);
+    aio_co_enter(fst->ctx, co);
+}
+
+static void coroutine_fn fsdev_throttle_config(FsThrottle *fst)
+{
+    if (throttle_enabled(&fst->cfg)) {
+        throttle_config(&fst->ts, QEMU_CLOCK_REALTIME, &fst->cfg);
+    } else {
+        throttle_restart_queues(fst);
+    }
+}
+
+void fsdev_set_io_throttle(ThrottleLimits *arg, FsThrottle *fst, Error **errp)
+{
+    ThrottleConfig cfg;
+
+    throttle_get_config(&fst->ts, &cfg);
+    throttle_limits_to_config(arg, &cfg, errp);
+
+    if (throttle_is_valid(&cfg, errp)) {
+        fst->cfg = cfg;
+        fsdev_throttle_config(fst);
+    }
+}
+
+void fsdev_get_io_throttle(FsThrottle *fst, ThrottleLimits **fs9pcfg,
+                           char *fsdevice)
+{
+    ThrottleConfig cfg = fst->cfg;
+    ThrottleLimits *fscfg = g_malloc0(sizeof(*fscfg));
+
+    fscfg->has_id = true;
+    fscfg->id = g_strdup(fsdevice);
+    throttle_config_to_limits(&cfg, fscfg);
+    *fs9pcfg = fscfg;
+}
+
 void fsdev_throttle_parse_opts(QemuOpts *opts, FsThrottle *fst, Error **errp)
 {
     throttle_parse_options(&fst->cfg, opts);
@@ -40,8 +127,9 @@ void fsdev_throttle_init(FsThrottle *fst)
 {
     if (throttle_enabled(&fst->cfg)) {
         throttle_init(&fst->ts);
+        fst->ctx = qemu_get_aio_context();
         throttle_timers_init(&fst->tt,
-                             qemu_get_aio_context(),
+                             fst->ctx,
                              QEMU_CLOCK_REALTIME,
                              fsdev_throttle_read_timer_cb,
                              fsdev_throttle_write_timer_cb,
@@ -62,11 +150,7 @@ void coroutine_fn fsdev_co_throttle_request(FsThrottle 
*fst, bool is_write,
         }
 
         throttle_account(&fst->ts, is_write, iov_size(iov, iovcnt));
-
-        if (!qemu_co_queue_empty(&fst->throttled_reqs[is_write]) &&
-            !throttle_schedule_timer(&fst->ts, &fst->tt, is_write)) {
-            qemu_co_queue_next(&fst->throttled_reqs[is_write]);
-        }
+        schedule_next_request(fst, is_write);
     }
 }
 
diff --git a/fsdev/qemu-fsdev-throttle.h b/fsdev/qemu-fsdev-throttle.h
index e418643..fc7409c 100644
--- a/fsdev/qemu-fsdev-throttle.h
+++ b/fsdev/qemu-fsdev-throttle.h
@@ -15,8 +15,6 @@
 #ifndef _FSDEV_THROTTLE_H
 #define _FSDEV_THROTTLE_H
 
-#include "block/aio.h"
-#include "qemu/main-loop.h"
 #include "qemu/coroutine.h"
 #include "qapi/error.h"
 #include "qemu/throttle.h"
@@ -25,6 +23,7 @@ typedef struct FsThrottle {
     ThrottleState ts;
     ThrottleTimers tt;
     ThrottleConfig cfg;
+    AioContext *ctx;
     CoQueue      throttled_reqs[2];
 } FsThrottle;
 
@@ -36,4 +35,10 @@ void coroutine_fn fsdev_co_throttle_request(FsThrottle *, 
bool ,
                                             struct iovec *, int);
 
 void fsdev_throttle_cleanup(FsThrottle *);
+
+void fsdev_set_io_throttle(ThrottleLimits *, FsThrottle *, Error **errp);
+
+void fsdev_get_io_throttle(FsThrottle *, ThrottleLimits **iothp,
+                           char *);
+
 #endif /* _FSDEV_THROTTLE_H */
diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c
index 266e442..07bb005 100644
--- a/fsdev/qemu-fsdev.c
+++ b/fsdev/qemu-fsdev.c
@@ -16,6 +16,7 @@
 #include "qemu-common.h"
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
+#include "qmp-commands.h"
 
 static QTAILQ_HEAD(FsDriverEntry_head, FsDriverListEntry) fsdriver_entries =
     QTAILQ_HEAD_INITIALIZER(fsdriver_entries);
@@ -98,3 +99,32 @@ FsDriverEntry *get_fsdev_fsentry(char *id)
     }
     return NULL;
 }
+
+void qmp_fsdev_set_io_throttle(ThrottleLimits *arg, Error **errp)
+{
+
+    FsDriverEntry *fse;
+
+    fse = get_fsdev_fsentry(arg->has_id ? arg->id : NULL);
+    if (!fse) {
+        error_setg(errp, "Not a valid fsdev device");
+        return;
+    }
+
+    fsdev_set_io_throttle(arg, &fse->fst, errp);
+}
+
+ThrottleLimitsList *qmp_query_fsdev_io_throttle(Error **errp)
+{
+    ThrottleLimitsList *head = NULL, *p_next;
+    struct FsDriverListEntry *fsle;
+
+    QTAILQ_FOREACH(fsle, &fsdriver_entries, next) {
+        p_next = g_new0(ThrottleLimitsList, 1);
+        fsdev_get_io_throttle(&fsle->fse.fst, &p_next->value,
+                              fsle->fse.fsdev_id);
+        p_next->next = head;
+        head = p_next;
+    }
+    return head;
+}
diff --git a/monitor.c b/monitor.c
index 9239f7a..d12334f 100644
--- a/monitor.c
+++ b/monitor.c
@@ -998,6 +998,11 @@ static void qmp_unregister_commands_hack(void)
     && !defined(TARGET_S390X)
     qmp_unregister_command(&qmp_commands, "query-cpu-definitions");
 #endif
+#ifndef CONFIG_VIRTFS
+    qmp_unregister_command(&qmp_commands, "fsdev-set-io-throttle");
+    qmp_unregister_command(&qmp_commands, "query-fsdev-io-throttle");
+#endif
+
 }
 
 void monitor_init_qmp_commands(void)
diff --git a/qapi-schema.json b/qapi-schema.json
index f3af2cb..bd55190 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -93,6 +93,10 @@
 { 'include': 'qapi/trace.json' }
 { 'include': 'qapi/introspect.json' }
 
+# QAPI fsdev definitions
+{ 'include': 'qapi/fsdev.json' }
+
+
 ##
 # = Miscellanea
 ##
diff --git a/qapi/fsdev.json b/qapi/fsdev.json
new file mode 100644
index 0000000..7babc30
--- /dev/null
+++ b/qapi/fsdev.json
@@ -0,0 +1,81 @@
+# -*- Mode: Python -*-
+
+##
+# == QAPI fsdev definitions
+##
+
+##
+# @fsdev-set-io-throttle:
+#
+# Change I/O limits for a 9p/fsdev device.
+#
+# I/O limits can be enabled by setting throttle value to non-zero number.
+#
+# I/O limits can be disabled by setting all throttle values to 0.
+#
+# Returns: Nothing on success
+#          If @device is not a valid fsdev device, GenericError
+#
+# Since: 2.11
+#
+# Example:
+#
+# -> { "execute": "fsdev-set-io-throttle",
+#      "arguments": { "id": "id0-1-0",
+#                     "bps": 1000000,
+#                     "bps_rd": 0,
+#                     "bps_wr": 0,
+#                     "iops": 0,
+#                     "iops_rd": 0,
+#                     "iops_wr": 0,
+#                     "bps_max": 8000000,
+#                     "bps_rd_max": 0,
+#                     "bps_wr_max": 0,
+#                     "iops_max": 0,
+#                     "iops_rd_max": 0,
+#                     "iops_wr_max": 0,
+#                     "bps_max_length": 60,
+#                     "iops_size": 0 } }
+# <- { "returns": {} }
+##
+{ 'command': 'fsdev-set-io-throttle', 'boxed': true,
+  'data': 'ThrottleLimits' }
+##
+# @query-fsdev-io-throttle:
+#
+# Returns: a list of @IOThrottle describing I/O throttle
+#          values of each fsdev device
+#
+# Since: 2.11
+#
+# Example:
+#
+# -> { "Execute": "query-fsdev-io-throttle" }
+# <- { "returns" : [
+#          {
+#              "id": "id0-hd0",
+#              "bps":1000000,
+#              "bps_rd":0,
+#              "bps_wr":0,
+#              "iops":1000000,
+#              "iops_rd":0,
+#              "iops_wr":0,
+#              "bps_max": 8000000,
+#              "bps_rd_max": 0,
+#              "bps_wr_max": 0,
+#              "iops_max": 0,
+#              "iops_rd_max": 0,
+#              "iops_wr_max": 0,
+#              "bps_max_length": 0,
+#              "bps_rd_max_length": 0,
+#              "bps_wr_max_length": 0,
+#              "iops_max_length": 0,
+#              "iops_rd_max_length": 0,
+#              "iops_wr_max_length": 0,
+#              "iops_size": 0
+#            }
+#          ]
+#      }
+#
+##
+{ 'command': 'query-fsdev-io-throttle', 'returns': [ 'ThrottleLimits' ] }
diff --git a/qmp.c b/qmp.c
index b86201e..8de2e23 100644
--- a/qmp.c
+++ b/qmp.c
@@ -130,6 +130,20 @@ void qmp_cpu_add(int64_t id, Error **errp)
     }
 }
 
+#if defined(_WIN64) || defined(_WIN32) || defined(__FreeBSD__)
+
+void qmp_fsdev_set_io_throttle(ThrottleLimits *arg, Error **errp)
+{
+    return;
+}
+
+ThrottleLimitsList *qmp_query_fsdev_io_throttle(Error **errp)
+{
+    return NULL;
+}
+
+#endif
+
 #ifndef CONFIG_VNC
 /* If VNC support is enabled, the "true" query-vnc command is
    defined in the VNC subsystem */
-- 
1.8.3.1