Commit d8e7d87e authored by Manos Pitsidianakis's avatar Manos Pitsidianakis Committed by Kevin Wolf
Browse files

block: add throttle block filter driver 



block/throttle.c uses existing I/O throttle infrastructure inside a
block filter driver. I/O operations are intercepted in the filter's
read/write coroutines, and referred to block/throttle-groups.c

The driver can be used with the syntax
-drive driver=throttle,file.filename=foo.qcow2,throttle-group=bar

which registers the throttle filter node with the ThrottleGroup 'bar'. The
given group must be created beforehand with object-add or -object.

Reviewed-by: default avatarAlberto Garcia <berto@igalia.com>
Signed-off-by: default avatarManos Pitsidianakis <el13635@mail.ntua.gr>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 432d889e

block/Makefile.objs

+1 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ block-obj-y += accounting.o dirty-bitmap.o 
block-obj-y += write-threshold.o

block-obj-y += backup.o

block-obj-$(CONFIG_REPLICATION) += replication.o

block-obj-y += throttle.o



block-obj-y += crypto.o

block/throttle-groups.c

+14 −1
Original line number Diff line number Diff line
@@ -101,6 +101,14 @@ static ThrottleGroup *throttle_group_by_name(const char *name) 
    return NULL;

}



/* This function reads throttle_groups and must be called under the global

 * mutex.

 */

bool throttle_group_exists(const char *name)

{

    return throttle_group_by_name(name) != NULL;

}



/* Increments the reference count of a ThrottleGroup given its name.

 *

 * If no ThrottleGroup is found with the given name a new one is
@@ -543,6 +551,11 @@ void throttle_group_unregister_tgm(ThrottleGroupMember *tgm) 
    ThrottleGroupMember *token;

    int i;



    if (!ts) {

        /* Discard already unregistered tgm */

        return;

    }



    assert(tgm->pending_reqs[0] == 0 && tgm->pending_reqs[1] == 0);

    assert(qemu_co_queue_empty(&tgm->throttled_reqs[0]));

    assert(qemu_co_queue_empty(&tgm->throttled_reqs[1]));
@@ -709,7 +722,7 @@ static void throttle_group_obj_complete(UserCreatable *obj, Error **errp) 
    assert(tg->name);



    /* error if name is duplicate */

    if (throttle_group_by_name(tg->name) != NULL) {

    if (throttle_group_exists(tg->name)) {

        error_setg(errp, "A group with this name already exists");

        return;

    }

block/throttle.c

0 → 100644
+237 −0
Original line number Diff line number Diff line 
/*

 * QEMU block throttling filter driver infrastructure

 *

 * Copyright (c) 2017 Manos Pitsidianakis

 *

 * 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/>.

 */



#include "qemu/osdep.h"

#include "block/throttle-groups.h"

#include "qemu/throttle-options.h"

#include "qapi/error.h"



static QemuOptsList throttle_opts = {

    .name = "throttle",

    .head = QTAILQ_HEAD_INITIALIZER(throttle_opts.head),

    .desc = {

        {

            .name = QEMU_OPT_THROTTLE_GROUP_NAME,

            .type = QEMU_OPT_STRING,

            .help = "Name of the throttle group",

        },

        { /* end of list */ }

    },

};



static int throttle_configure_tgm(BlockDriverState *bs,

                                  ThrottleGroupMember *tgm,

                                  QDict *options, Error **errp)

{

    int ret;

    const char *group_name;

    Error *local_err = NULL;

    QemuOpts *opts = qemu_opts_create(&throttle_opts, NULL, 0, &error_abort);



    qemu_opts_absorb_qdict(opts, options, &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        ret = -EINVAL;

        goto fin;

    }



    group_name = qemu_opt_get(opts, QEMU_OPT_THROTTLE_GROUP_NAME);

    if (!group_name) {

        error_setg(errp, "Please specify a throttle group");

        ret = -EINVAL;

        goto fin;

    } else if (!throttle_group_exists(group_name)) {

        error_setg(errp, "Throttle group '%s' does not exist", group_name);

        ret = -EINVAL;

        goto fin;

    }



    /* Register membership to group with name group_name */

    throttle_group_register_tgm(tgm, group_name, bdrv_get_aio_context(bs));

    ret = 0;

fin:

    qemu_opts_del(opts);

    return ret;

}



static int throttle_open(BlockDriverState *bs, QDict *options,

                         int flags, Error **errp)

{

    ThrottleGroupMember *tgm = bs->opaque;



    bs->file = bdrv_open_child(NULL, options, "file", bs,

                               &child_file, false, errp);

    if (!bs->file) {

        return -EINVAL;

    }

    bs->supported_write_flags = bs->file->bs->supported_write_flags;

    bs->supported_zero_flags = bs->file->bs->supported_zero_flags;



    return throttle_configure_tgm(bs, tgm, options, errp);

}



static void throttle_close(BlockDriverState *bs)

{

    ThrottleGroupMember *tgm = bs->opaque;

    throttle_group_unregister_tgm(tgm);

}





static int64_t throttle_getlength(BlockDriverState *bs)

{

    return bdrv_getlength(bs->file->bs);

}



static int coroutine_fn throttle_co_preadv(BlockDriverState *bs,

                                           uint64_t offset, uint64_t bytes,

                                           QEMUIOVector *qiov, int flags)

{



    ThrottleGroupMember *tgm = bs->opaque;

    throttle_group_co_io_limits_intercept(tgm, bytes, false);



    return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);

}



static int coroutine_fn throttle_co_pwritev(BlockDriverState *bs,

                                            uint64_t offset, uint64_t bytes,

                                            QEMUIOVector *qiov, int flags)

{

    ThrottleGroupMember *tgm = bs->opaque;

    throttle_group_co_io_limits_intercept(tgm, bytes, true);



    return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);

}



static int coroutine_fn throttle_co_pwrite_zeroes(BlockDriverState *bs,

                                                  int64_t offset, int bytes,

                                                  BdrvRequestFlags flags)

{

    ThrottleGroupMember *tgm = bs->opaque;

    throttle_group_co_io_limits_intercept(tgm, bytes, true);



    return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);

}



static int coroutine_fn throttle_co_pdiscard(BlockDriverState *bs,

                                             int64_t offset, int bytes)

{

    ThrottleGroupMember *tgm = bs->opaque;

    throttle_group_co_io_limits_intercept(tgm, bytes, true);



    return bdrv_co_pdiscard(bs->file->bs, offset, bytes);

}



static int throttle_co_flush(BlockDriverState *bs)

{

    return bdrv_co_flush(bs->file->bs);

}



static void throttle_detach_aio_context(BlockDriverState *bs)

{

    ThrottleGroupMember *tgm = bs->opaque;

    throttle_group_detach_aio_context(tgm);

}



static void throttle_attach_aio_context(BlockDriverState *bs,

                                        AioContext *new_context)

{

    ThrottleGroupMember *tgm = bs->opaque;

    throttle_group_attach_aio_context(tgm, new_context);

}



static int throttle_reopen_prepare(BDRVReopenState *reopen_state,

                                   BlockReopenQueue *queue, Error **errp)

{

    ThrottleGroupMember *tgm;



    assert(reopen_state != NULL);

    assert(reopen_state->bs != NULL);



    reopen_state->opaque = g_new0(ThrottleGroupMember, 1);

    tgm = reopen_state->opaque;



    return throttle_configure_tgm(reopen_state->bs, tgm, reopen_state->options,

            errp);

}



static void throttle_reopen_commit(BDRVReopenState *reopen_state)

{

    ThrottleGroupMember *old_tgm = reopen_state->bs->opaque;

    ThrottleGroupMember *new_tgm = reopen_state->opaque;



    throttle_group_unregister_tgm(old_tgm);

    g_free(old_tgm);

    reopen_state->bs->opaque = new_tgm;

    reopen_state->opaque = NULL;

}



static void throttle_reopen_abort(BDRVReopenState *reopen_state)

{

    ThrottleGroupMember *tgm = reopen_state->opaque;



    throttle_group_unregister_tgm(tgm);

    g_free(tgm);

    reopen_state->opaque = NULL;

}



static bool throttle_recurse_is_first_non_filter(BlockDriverState *bs,

                                                 BlockDriverState *candidate)

{

    return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);

}



static BlockDriver bdrv_throttle = {

    .format_name                        =   "throttle",

    .protocol_name                      =   "throttle",

    .instance_size                      =   sizeof(ThrottleGroupMember),



    .bdrv_file_open                     =   throttle_open,

    .bdrv_close                         =   throttle_close,

    .bdrv_co_flush                      =   throttle_co_flush,



    .bdrv_child_perm                    =   bdrv_filter_default_perms,



    .bdrv_getlength                     =   throttle_getlength,



    .bdrv_co_preadv                     =   throttle_co_preadv,

    .bdrv_co_pwritev                    =   throttle_co_pwritev,



    .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,

    .bdrv_co_pdiscard                   =   throttle_co_pdiscard,



    .bdrv_recurse_is_first_non_filter   =   throttle_recurse_is_first_non_filter,



    .bdrv_attach_aio_context            =   throttle_attach_aio_context,

    .bdrv_detach_aio_context            =   throttle_detach_aio_context,



    .bdrv_reopen_prepare                =   throttle_reopen_prepare,

    .bdrv_reopen_commit                 =   throttle_reopen_commit,

    .bdrv_reopen_abort                  =   throttle_reopen_abort,

    .bdrv_co_get_block_status           =   bdrv_co_get_block_status_from_file,



    .is_filter                          =   true,

};



static void bdrv_throttle_init(void)

{

    bdrv_register(&bdrv_throttle);

}



block_init(bdrv_throttle_init);

include/block/throttle-groups.h

+5 −0
Original line number Diff line number Diff line
@@ -76,5 +76,10 @@ void coroutine_fn throttle_group_co_io_limits_intercept(ThrottleGroupMember *tgm 
void throttle_group_attach_aio_context(ThrottleGroupMember *tgm,

                                       AioContext *new_context);

void throttle_group_detach_aio_context(ThrottleGroupMember *tgm);

/*

 * throttle_group_exists() must be called under the global

 * mutex.

 */

bool throttle_group_exists(const char *name);



#endif

include/qemu/throttle-options.h

+1 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#define QEMU_OPT_BPS_WRITE_MAX "bps-write-max"

#define QEMU_OPT_BPS_WRITE_MAX_LENGTH "bps-write-max-length"

#define QEMU_OPT_IOPS_SIZE "iops-size"

#define QEMU_OPT_THROTTLE_GROUP_NAME "throttle-group"



#define THROTTLE_OPT_PREFIX "throttling."

#define THROTTLE_OPTS \