Re: [Qemu-devel] [PATCH v7 6/6] fsdev: QMP interface for throttling

[Markus Armbruster <armbru@redhat.com>]

Pradeep Jagadeesh <pradeepkiruvale@gmail.com> writes:

> 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 <pradeep.jagadeesh@huawei.com>
> ---
>  Makefile                    |  4 +++
>  fsdev/qemu-fsdev-dummy.c    | 10 ++++++
>  fsdev/qemu-fsdev-throttle.c | 76 +++++++++++++++++++++++++++++++++++++++-
>  fsdev/qemu-fsdev-throttle.h | 13 +++++++
>  fsdev/qemu-fsdev.c          | 37 ++++++++++++++++++++
>  monitor.c                   |  5 +++
>  qapi-schema.json            |  3 ++
>  qapi/fsdev.json             | 84 +++++++++++++++++++++++++++++++++++++++++++++
>  qmp.c                       | 14 ++++++++
>  9 files changed, 245 insertions(+), 1 deletion(-)
>  create mode 100644 qapi/fsdev.json
>
> diff --git a/Makefile b/Makefile
> index 16a0430..4fd7625 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -416,6 +416,10 @@ qapi-modules = $(SRC_PATH)/qapi-schema.json $(SRC_PATH)/qapi/common.json \
>                 $(SRC_PATH)/qapi/crypto.json $(SRC_PATH)/qapi/rocker.json \
>                 $(SRC_PATH)/qapi/trace.json
>  
> +ifdef CONFIG_VIRTFS

Uh, qapi-schema.json includes fsdev.json *unconditionally*, doesn't it?

> +qapi-modules += $(SRC_PATH)/qapi/fsdev.json
> +endif
> +
>  qapi-types.c qapi-types.h :\
>  $(qapi-modules) $(SRC_PATH)/scripts/qapi-types.py $(qapi-py)
>  	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-types.py \
> diff --git a/fsdev/qemu-fsdev-dummy.c b/fsdev/qemu-fsdev-dummy.c
> index 6dc0fbc..f33305d 100644
> --- a/fsdev/qemu-fsdev-dummy.c
> +++ b/fsdev/qemu-fsdev-dummy.c
> @@ -19,3 +19,13 @@ int qemu_fsdev_add(QemuOpts *opts)
>  {
>      return 0;
>  }
> +
> +void qmp_fsdev_set_io_throttle(IOThrottle *arg, Error **errp)
> +{
> +  return;

Indentation is off.

> +}
> +
> +IOThrottleList *qmp_query_fsdev_io_throttle(Error **errp)
> +{
> +    abort();
> +}

Any particular reason why one of the stubs abort()s, but not the other?

> diff --git a/fsdev/qemu-fsdev-throttle.c b/fsdev/qemu-fsdev-throttle.c
> index c5e2499..4483533 100644
> --- a/fsdev/qemu-fsdev-throttle.c
> +++ b/fsdev/qemu-fsdev-throttle.c
> @@ -16,7 +16,6 @@
>  #include "qemu/error-report.h"
>  #include "qemu-fsdev-throttle.h"
>  #include "qemu/iov.h"
> -#include "qemu/throttle-options.h"
>  
>  static void fsdev_throttle_read_timer_cb(void *opaque)
>  {
> @@ -30,6 +29,81 @@ static void fsdev_throttle_write_timer_cb(void *opaque)
>      qemu_co_enter_next(&fst->throttled_reqs[true]);
>  }
>  
> +void fsdev_set_io_throttle(IOThrottle *arg, FsThrottle *fst, Error **errp)
> +{
> +    ThrottleConfig cfg;
> +
> +    throttle_set_io_limits(&cfg, arg);
> +
> +    if (throttle_is_valid(&cfg, errp)) {
> +        fst->cfg = cfg;
> +        fsdev_throttle_init(fst);
> +    }
> +}
> +
> +void fsdev_get_io_throttle(FsThrottle *fst, IOThrottle **fs9pcfg,
> +                           char *fsdevice, Error **errp)
> +{
> +
> +    ThrottleConfig cfg = fst->cfg;
> +    IOThrottle *fscfg = g_malloc0(sizeof(*fscfg));
> +
> +    fscfg->has_id = true;
> +    fscfg->id = g_strdup(fsdevice);
> +    fscfg->bps = cfg.buckets[THROTTLE_BPS_TOTAL].avg;
> +    fscfg->bps_rd = cfg.buckets[THROTTLE_BPS_READ].avg;
> +    fscfg->bps_wr = cfg.buckets[THROTTLE_BPS_WRITE].avg;
> +
> +    fscfg->iops = cfg.buckets[THROTTLE_OPS_TOTAL].avg;
> +    fscfg->iops_rd = cfg.buckets[THROTTLE_OPS_READ].avg;
> +    fscfg->iops_wr = cfg.buckets[THROTTLE_OPS_WRITE].avg;
> +
> +    fscfg->has_bps_max     = cfg.buckets[THROTTLE_BPS_TOTAL].max;
> +    fscfg->bps_max         = cfg.buckets[THROTTLE_BPS_TOTAL].max;
> +    fscfg->has_bps_rd_max  = cfg.buckets[THROTTLE_BPS_READ].max;
> +    fscfg->bps_rd_max      = cfg.buckets[THROTTLE_BPS_READ].max;
> +    fscfg->has_bps_wr_max  = cfg.buckets[THROTTLE_BPS_WRITE].max;
> +    fscfg->bps_wr_max      = cfg.buckets[THROTTLE_BPS_WRITE].max;
> +
> +    fscfg->has_iops_max    = cfg.buckets[THROTTLE_OPS_TOTAL].max;
> +    fscfg->iops_max        = cfg.buckets[THROTTLE_OPS_TOTAL].max;
> +    fscfg->has_iops_rd_max = cfg.buckets[THROTTLE_OPS_READ].max;
> +    fscfg->iops_rd_max     = cfg.buckets[THROTTLE_OPS_READ].max;
> +    fscfg->has_iops_wr_max = cfg.buckets[THROTTLE_OPS_WRITE].max;
> +    fscfg->iops_wr_max     = cfg.buckets[THROTTLE_OPS_WRITE].max;
> +
> +    fscfg->has_bps_max_length     = fscfg->has_bps_max;
> +    fscfg->bps_max_length         =
> +         cfg.buckets[THROTTLE_BPS_TOTAL].burst_length;
> +    fscfg->has_bps_rd_max_length  = fscfg->has_bps_rd_max;
> +    fscfg->bps_rd_max_length      =
> +         cfg.buckets[THROTTLE_BPS_READ].burst_length;
> +    fscfg->has_bps_wr_max_length  = fscfg->has_bps_wr_max;
> +    fscfg->bps_wr_max_length      =
> +         cfg.buckets[THROTTLE_BPS_WRITE].burst_length;
> +
> +    fscfg->has_iops_max_length    = fscfg->has_iops_max;
> +    fscfg->iops_max_length        =
> +         cfg.buckets[THROTTLE_OPS_TOTAL].burst_length;
> +    fscfg->has_iops_rd_max_length = fscfg->has_iops_rd_max;
> +    fscfg->iops_rd_max_length     =
> +         cfg.buckets[THROTTLE_OPS_READ].burst_length;
> +    fscfg->has_iops_wr_max_length = fscfg->has_iops_wr_max;
> +    fscfg->iops_wr_max_length     =
> +         cfg.buckets[THROTTLE_OPS_WRITE].burst_length;
> +
> +    fscfg->bps_max_length = cfg.buckets[THROTTLE_BPS_TOTAL].burst_length;
> +    fscfg->bps_rd_max_length = cfg.buckets[THROTTLE_BPS_READ].burst_length;
> +    fscfg->bps_wr_max_length = cfg.buckets[THROTTLE_BPS_WRITE].burst_length;
> +    fscfg->iops_max_length = cfg.buckets[THROTTLE_OPS_TOTAL].burst_length;
> +    fscfg->iops_rd_max_length = cfg.buckets[THROTTLE_OPS_READ].burst_length;
> +    fscfg->iops_wr_max_length = cfg.buckets[THROTTLE_OPS_WRITE].burst_length;
> +
> +    fscfg->iops_size = cfg.op_size;

Duplicates bdrv_block_device_info(), which makes me sad.  Could the
common code be factored out?

> +
> +    *fs9pcfg = fscfg;
> +}

Why do you need to store through a parameter?  What's wrong with simply
returning fscfg?

> +
>  void fsdev_throttle_parse_opts(QemuOpts *opts, FsThrottle *fst, Error **errp)
>  {
>      throttle_parse_options(&fst->cfg, opts);
> diff --git a/fsdev/qemu-fsdev-throttle.h b/fsdev/qemu-fsdev-throttle.h
> index e418643..a49b2e5 100644
> --- a/fsdev/qemu-fsdev-throttle.h
> +++ b/fsdev/qemu-fsdev-throttle.h
> @@ -20,6 +20,13 @@

   #include "block/aio.h"
   #include "qemu/main-loop.h"
>  #include "qemu/coroutine.h"
>  #include "qapi/error.h"
>  #include "qemu/throttle.h"
> +#include "qemu/throttle-options.h"
> +#include "qapi/qmp/qerror.h"
> +#include "qapi/qmp/types.h"
> +#include "qapi-visit.h"
> +#include "qapi/qobject-output-visitor.h"
> +#include "qapi/util.h"
> +#include "qmp-commands.h"

The header actually needs two out of these twelve: coroutine.h and
throttle.h.  Lazy use of include makes for slow compiles.  Drop the ten
unused ones, then fix up the .c to include what they need.

>  
>  typedef struct FsThrottle {
>      ThrottleState ts;
> @@ -36,4 +43,10 @@ void coroutine_fn fsdev_co_throttle_request(FsThrottle *, bool ,
>                                              struct iovec *, int);
>  
>  void fsdev_throttle_cleanup(FsThrottle *);
> +
> +void fsdev_set_io_throttle(IOThrottle *, FsThrottle *, Error **errp);
> +
> +void fsdev_get_io_throttle(FsThrottle *, IOThrottle **iothp,
> +                           char *, Error **errp);
> +
>  #endif /* _FSDEV_THROTTLE_H */
> diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c
> index 266e442..0eca7c3 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 +99,39 @@ FsDriverEntry *get_fsdev_fsentry(char *id)
>      }
>      return NULL;
>  }
> +
> +void qmp_fsdev_set_io_throttle(IOThrottle *arg, Error **errp)
> +{
> +
> +    FsDriverEntry *fse;
> +
> +    fse = get_fsdev_fsentry(arg->has_id ? arg->id : NULL);
> +    if (!fse) {
> +        return;

Why isn't this an error?

> +    }
> +
> +    fsdev_set_io_throttle(arg, &fse->fst, errp);
> +}
> +
> +IOThrottleList *qmp_query_fsdev_io_throttle(Error **errp)
> +{
> +    IOThrottleList *head = NULL, *p_next;
> +    struct FsDriverListEntry *fsle;
> +    Error *local_err = NULL;
> +
> +    QTAILQ_FOREACH(fsle, &fsdriver_entries, next) {
> +        p_next = g_malloc0(sizeof(*p_next));

Okay, but you might want to consider g_new0(IOThrottleList) for a bit of
extra type checking.

> +        fsdev_get_io_throttle(&fsle->fse.fst, &p_next->value,
> +                            fsle->fse.fsdev_id, &local_err);

Indentation is off.

> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            g_free(p_next);
> +            qapi_free_IOThrottleList(head);
> +            return NULL;
> +        }
> +
> +        p_next->next = head;
> +        head = p_next;
> +    }
> +    return head;
> +}
> diff --git a/monitor.c b/monitor.c
> index 3c369f4..592a39e 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -997,6 +997,11 @@ 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 4b50b65..dc676be 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -81,6 +81,9 @@
>  # QAPI block definitions
>  { 'include': 'qapi/block.json' }
>  
> +# QAPI fsdev definitions
> +{ 'include': 'qapi/fsdev.json' }
> +
>  # QAPI event definitions
>  { 'include': 'qapi/event.json' }
>  
> diff --git a/qapi/fsdev.json b/qapi/fsdev.json
> new file mode 100644
> index 0000000..eff1efe
> --- /dev/null
> +++ b/qapi/fsdev.json
> @@ -0,0 +1,84 @@
> +# -*- Mode: Python -*-
> +
> +##
> +# == QAPI fsdev definitions
> +##
> +
> +# QAPI common definitions
> +{ 'include': 'iothrottle.json' }
> +
> +##
> +# @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, DeviceNotFound

Aha, qmp_fsdev_set_io_throttle()'s early return should be an error!
Make it GenericError rather than DeviceNotFound, please; just use
error_setg().

> +#
> +# Since: 2.10
> +#
> +# 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': 'IOThrottle' }
> +##
> +# @query-fsdev-io-throttle:
> +#
> +# Returns: a list of @IOThrottle describing io throttle values of each fsdev device

"io" is not a word, make it "I/O".  Also: long line.  Please wrap your
comment lines around column 70.

> +#
> +# Since: 2.10
> +#
> +# Example:
> +#
> +# -> { "Execute": "query-fsdev-io-throttle" }
> +# <- { "returns" : [
> +#          {
> +#             "id": "id0-hd0",

Indentation is off again.

> +#              "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': [ 'IOThrottle' ] }
> +

Trailing blank line.

> diff --git a/qmp.c b/qmp.c
> index 7ee9bcf..8a60f2c 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(IOThrottle *arg, Error **errp)
> +{
> +  return;

Indentation is off.

> +}
> +
> +IOThrottleList *qmp_query_fsdev_io_throttle(Error **errp)
> +{
> +    abort();
> +}
> +
> +#endif
> +

Why do you need stubs both here and in fsdev/qemu-fsdev-dummy.c?

>  #ifndef CONFIG_VNC
>  /* If VNC support is enabled, the "true" query-vnc command is
>     defined in the VNC subsystem */