diff options
Diffstat (limited to 'block.c')
| -rw-r--r-- | block.c | 613 |
1 files changed, 600 insertions, 13 deletions
@@ -30,6 +30,7 @@ #include "qjson.h" #include "qemu-coroutine.h" #include "qmp-commands.h" +#include "qemu-timer.h" #ifdef CONFIG_BSD #include <sys/types.h> @@ -73,6 +74,13 @@ static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs, bool is_write); static void coroutine_fn bdrv_co_do_rw(void *opaque); +static bool bdrv_exceed_bps_limits(BlockDriverState *bs, int nb_sectors, + bool is_write, double elapsed_time, uint64_t *wait); +static bool bdrv_exceed_iops_limits(BlockDriverState *bs, bool is_write, + double elapsed_time, uint64_t *wait); +static bool bdrv_exceed_io_limits(BlockDriverState *bs, int nb_sectors, + bool is_write, int64_t *wait); + static QTAILQ_HEAD(, BlockDriverState) bdrv_states = QTAILQ_HEAD_INITIALIZER(bdrv_states); @@ -105,6 +113,79 @@ int is_windows_drive(const char *filename) } #endif +/* throttling disk I/O limits */ +void bdrv_io_limits_disable(BlockDriverState *bs) +{ + bs->io_limits_enabled = false; + + while (qemu_co_queue_next(&bs->throttled_reqs)); + + if (bs->block_timer) { + qemu_del_timer(bs->block_timer); + qemu_free_timer(bs->block_timer); + bs->block_timer = NULL; + } + + bs->slice_start = 0; + bs->slice_end = 0; + bs->slice_time = 0; + memset(&bs->io_base, 0, sizeof(bs->io_base)); +} + +static void bdrv_block_timer(void *opaque) +{ + BlockDriverState *bs = opaque; + + qemu_co_queue_next(&bs->throttled_reqs); +} + +void bdrv_io_limits_enable(BlockDriverState *bs) +{ + qemu_co_queue_init(&bs->throttled_reqs); + bs->block_timer = qemu_new_timer_ns(vm_clock, bdrv_block_timer, bs); + bs->slice_time = 5 * BLOCK_IO_SLICE_TIME; + bs->slice_start = qemu_get_clock_ns(vm_clock); + bs->slice_end = bs->slice_start + bs->slice_time; + memset(&bs->io_base, 0, sizeof(bs->io_base)); + bs->io_limits_enabled = true; +} + +bool bdrv_io_limits_enabled(BlockDriverState *bs) +{ + BlockIOLimit *io_limits = &bs->io_limits; + return io_limits->bps[BLOCK_IO_LIMIT_READ] + || io_limits->bps[BLOCK_IO_LIMIT_WRITE] + || io_limits->bps[BLOCK_IO_LIMIT_TOTAL] + || io_limits->iops[BLOCK_IO_LIMIT_READ] + || io_limits->iops[BLOCK_IO_LIMIT_WRITE] + || io_limits->iops[BLOCK_IO_LIMIT_TOTAL]; +} + +static void bdrv_io_limits_intercept(BlockDriverState *bs, + bool is_write, int nb_sectors) +{ + int64_t wait_time = -1; + + if (!qemu_co_queue_empty(&bs->throttled_reqs)) { + qemu_co_queue_wait(&bs->throttled_reqs); + } + + /* In fact, we hope to keep each request's timing, in FIFO mode. The next + * throttled requests will not be dequeued until the current request is + * allowed to be serviced. So if the current request still exceeds the + * limits, it will be inserted to the head. All requests followed it will + * be still in throttled_reqs queue. + */ + + while (bdrv_exceed_io_limits(bs, nb_sectors, is_write, &wait_time)) { + qemu_mod_timer(bs->block_timer, + wait_time + qemu_get_clock_ns(vm_clock)); + qemu_co_queue_wait_insert_head(&bs->throttled_reqs); + } + + qemu_co_queue_next(&bs->throttled_reqs); +} + /* check if the path starts with "<protocol>:" */ static int path_has_protocol(const char *path) { @@ -457,6 +538,22 @@ int bdrv_parse_cache_flags(const char *mode, int *flags) return 0; } +/** + * The copy-on-read flag is actually a reference count so multiple users may + * use the feature without worrying about clobbering its previous state. + * Copy-on-read stays enabled until all users have called to disable it. + */ +void bdrv_enable_copy_on_read(BlockDriverState *bs) +{ + bs->copy_on_read++; +} + +void bdrv_disable_copy_on_read(BlockDriverState *bs) +{ + assert(bs->copy_on_read > 0); + bs->copy_on_read--; +} + /* * Common part for opening disk images and files */ @@ -478,6 +575,11 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename, bs->growable = 0; bs->buffer_alignment = 512; + assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */ + if ((flags & BDRV_O_RDWR) && (flags & BDRV_O_COPY_ON_READ)) { + bdrv_enable_copy_on_read(bs); + } + pstrcpy(bs->filename, sizeof(bs->filename), filename); bs->backing_file[0] = '\0'; @@ -687,6 +789,11 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags, bdrv_dev_change_media_cb(bs, true); } + /* throttling disk I/O limits */ + if (bs->io_limits_enabled) { + bdrv_io_limits_enable(bs); + } + return 0; unlink_and_fail: @@ -715,6 +822,7 @@ void bdrv_close(BlockDriverState *bs) #endif bs->opaque = NULL; bs->drv = NULL; + bs->copy_on_read = 0; if (bs->file != NULL) { bdrv_close(bs->file); @@ -722,6 +830,11 @@ void bdrv_close(BlockDriverState *bs) bdrv_dev_change_media_cb(bs, false); } + + /*throttling disk I/O limits*/ + if (bs->io_limits_enabled) { + bdrv_io_limits_disable(bs); + } } void bdrv_close_all(void) @@ -733,6 +846,25 @@ void bdrv_close_all(void) } } +/* + * Wait for pending requests to complete across all BlockDriverStates + * + * This function does not flush data to disk, use bdrv_flush_all() for that + * after calling this function. + */ +void bdrv_drain_all(void) +{ + BlockDriverState *bs; + + qemu_aio_flush(); + + /* If requests are still pending there is a bug somewhere */ + QTAILQ_FOREACH(bs, &bdrv_states, list) { + assert(QLIST_EMPTY(&bs->tracked_requests)); + assert(qemu_co_queue_empty(&bs->throttled_reqs)); + } +} + /* make a BlockDriverState anonymous by removing from bdrv_state list. Also, NULL terminate the device_name to prevent double remove */ void bdrv_make_anon(BlockDriverState *bs) @@ -922,7 +1054,7 @@ int bdrv_commit(BlockDriverState *bs) buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); for (sector = 0; sector < total_sectors; sector += n) { - if (drv->bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n)) { + if (bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n)) { if (bdrv_read(bs, sector, buf, n) != 0) { ret = -EIO; @@ -980,6 +1112,118 @@ void bdrv_commit_all(void) } } +struct BdrvTrackedRequest { + BlockDriverState *bs; + int64_t sector_num; + int nb_sectors; + bool is_write; + QLIST_ENTRY(BdrvTrackedRequest) list; + Coroutine *co; /* owner, used for deadlock detection */ + CoQueue wait_queue; /* coroutines blocked on this request */ +}; + +/** + * Remove an active request from the tracked requests list + * + * This function should be called when a tracked request is completing. + */ +static void tracked_request_end(BdrvTrackedRequest *req) +{ + QLIST_REMOVE(req, list); + qemu_co_queue_restart_all(&req->wait_queue); +} + +/** + * Add an active request to the tracked requests list + */ +static void tracked_request_begin(BdrvTrackedRequest *req, + BlockDriverState *bs, + int64_t sector_num, + int nb_sectors, bool is_write) +{ + *req = (BdrvTrackedRequest){ + .bs = bs, + .sector_num = sector_num, + .nb_sectors = nb_sectors, + .is_write = is_write, + .co = qemu_coroutine_self(), + }; + + qemu_co_queue_init(&req->wait_queue); + + QLIST_INSERT_HEAD(&bs->tracked_requests, req, list); +} + +/** + * Round a region to cluster boundaries + */ +static void round_to_clusters(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, + int64_t *cluster_sector_num, + int *cluster_nb_sectors) +{ + BlockDriverInfo bdi; + + if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) { + *cluster_sector_num = sector_num; + *cluster_nb_sectors = nb_sectors; + } else { + int64_t c = bdi.cluster_size / BDRV_SECTOR_SIZE; + *cluster_sector_num = QEMU_ALIGN_DOWN(sector_num, c); + *cluster_nb_sectors = QEMU_ALIGN_UP(sector_num - *cluster_sector_num + + nb_sectors, c); + } +} + +static bool tracked_request_overlaps(BdrvTrackedRequest *req, + int64_t sector_num, int nb_sectors) { + /* aaaa bbbb */ + if (sector_num >= req->sector_num + req->nb_sectors) { + return false; + } + /* bbbb aaaa */ + if (req->sector_num >= sector_num + nb_sectors) { + return false; + } + return true; +} + +static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs, + int64_t sector_num, int nb_sectors) +{ + BdrvTrackedRequest *req; + int64_t cluster_sector_num; + int cluster_nb_sectors; + bool retry; + + /* If we touch the same cluster it counts as an overlap. This guarantees + * that allocating writes will be serialized and not race with each other + * for the same cluster. For example, in copy-on-read it ensures that the + * CoR read and write operations are atomic and guest writes cannot + * interleave between them. + */ + round_to_clusters(bs, sector_num, nb_sectors, + &cluster_sector_num, &cluster_nb_sectors); + + do { + retry = false; + QLIST_FOREACH(req, &bs->tracked_requests, list) { + if (tracked_request_overlaps(req, cluster_sector_num, + cluster_nb_sectors)) { + /* Hitting this means there was a reentrant request, for + * example, a block driver issuing nested requests. This must + * never happen since it means deadlock. + */ + assert(qemu_coroutine_self() != req->co); + + qemu_co_queue_wait(&req->wait_queue); + retry = true; + break; + } + } + } while (retry); +} + /* * Return values: * 0 - success @@ -1252,6 +1496,61 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, return 0; } +static int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) +{ + /* Perform I/O through a temporary buffer so that users who scribble over + * their read buffer while the operation is in progress do not end up + * modifying the image file. This is critical for zero-copy guest I/O + * where anything might happen inside guest memory. + */ + void *bounce_buffer; + + struct iovec iov; + QEMUIOVector bounce_qiov; + int64_t cluster_sector_num; + int cluster_nb_sectors; + size_t skip_bytes; + int ret; + + /* Cover entire cluster so no additional backing file I/O is required when + * allocating cluster in the image file. + */ + round_to_clusters(bs, sector_num, nb_sectors, + &cluster_sector_num, &cluster_nb_sectors); + + trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, + cluster_sector_num, cluster_nb_sectors); + + iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE; + iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len); + qemu_iovec_init_external(&bounce_qiov, &iov, 1); + + ret = bs->drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors, + &bounce_qiov); + if (ret < 0) { + goto err; + } + + ret = bs->drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors, + &bounce_qiov); + if (ret < 0) { + /* It might be okay to ignore write errors for guest requests. If this + * is a deliberate copy-on-read then we don't want to ignore the error. + * Simply report it in all cases. + */ + goto err; + } + + skip_bytes = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE; + qemu_iovec_from_buffer(qiov, bounce_buffer + skip_bytes, + nb_sectors * BDRV_SECTOR_SIZE); + +err: + qemu_vfree(bounce_buffer); + return ret; +} + /* * Handle a read request in coroutine context */ @@ -1259,6 +1558,8 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { BlockDriver *drv = bs->drv; + BdrvTrackedRequest req; + int ret; if (!drv) { return -ENOMEDIUM; @@ -1267,7 +1568,36 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, return -EIO; } - return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov); + /* throttling disk read I/O */ + if (bs->io_limits_enabled) { + bdrv_io_limits_intercept(bs, false, nb_sectors); + } + + if (bs->copy_on_read) { + wait_for_overlapping_requests(bs, sector_num, nb_sectors); + } + + tracked_request_begin(&req, bs, sector_num, nb_sectors, false); + + if (bs->copy_on_read) { + int pnum; + + ret = bdrv_co_is_allocated(bs, sector_num, nb_sectors, &pnum); + if (ret < 0) { + goto out; + } + + if (!ret || pnum != nb_sectors) { + ret = bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, qiov); + goto out; + } + } + + ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov); + +out: + tracked_request_end(&req); + return ret; } int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num, @@ -1285,6 +1615,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { BlockDriver *drv = bs->drv; + BdrvTrackedRequest req; int ret; if (!bs->drv) { @@ -1297,6 +1628,17 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, return -EIO; } + /* throttling disk write I/O */ + if (bs->io_limits_enabled) { + bdrv_io_limits_intercept(bs, true, nb_sectors); + } + + if (bs->copy_on_read) { + wait_for_overlapping_requests(bs, sector_num, nb_sectors); + } + + tracked_request_begin(&req, bs, sector_num, nb_sectors, true); + ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov); if (bs->dirty_bitmap) { @@ -1307,6 +1649,8 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, bs->wr_highest_sector = sector_num + nb_sectors - 1; } + tracked_request_end(&req); + return ret; } @@ -1526,6 +1870,14 @@ void bdrv_get_geometry_hint(BlockDriverState *bs, *psecs = bs->secs; } +/* throttling disk io limits */ +void bdrv_set_io_limits(BlockDriverState *bs, + BlockIOLimit *io_limits) +{ + bs->io_limits = *io_limits; + bs->io_limits_enabled = bdrv_io_limits_enabled(bs); +} + /* Recognize floppy formats */ typedef struct FDFormat { FDriveType drive; @@ -1778,31 +2130,87 @@ int bdrv_has_zero_init(BlockDriverState *bs) return 1; } +typedef struct BdrvCoIsAllocatedData { + BlockDriverState *bs; + int64_t sector_num; + int nb_sectors; + int *pnum; + int ret; + bool done; +} BdrvCoIsAllocatedData; + /* * Returns true iff the specified sector is present in the disk image. Drivers * not implementing the functionality are assumed to not support backing files, * hence all their sectors are reported as allocated. * + * If 'sector_num' is beyond the end of the disk image the return value is 0 + * and 'pnum' is set to 0. + * * 'pnum' is set to the number of sectors (including and immediately following * the specified sector) that are known to be in the same * allocated/unallocated state. * - * 'nb_sectors' is the max value 'pnum' should be set to. + * 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes + * beyond the end of the disk image it will be clamped. */ -int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, - int *pnum) +int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, int *pnum) { int64_t n; - if (!bs->drv->bdrv_is_allocated) { - if (sector_num >= bs->total_sectors) { - *pnum = 0; - return 0; - } - n = bs->total_sectors - sector_num; - *pnum = (n < nb_sectors) ? (n) : (nb_sectors); + + if (sector_num >= bs->total_sectors) { + *pnum = 0; + return 0; + } + + n = bs->total_sectors - sector_num; + if (n < nb_sectors) { + nb_sectors = n; + } + + if (!bs->drv->bdrv_co_is_allocated) { + *pnum = nb_sectors; return 1; } - return bs->drv->bdrv_is_allocated(bs, sector_num, nb_sectors, pnum); + + return bs->drv->bdrv_co_is_allocated(bs, sector_num, nb_sectors, pnum); +} + +/* Coroutine wrapper for bdrv_is_allocated() */ +static void coroutine_fn bdrv_is_allocated_co_entry(void *opaque) +{ + BdrvCoIsAllocatedData *data = opaque; + BlockDriverState *bs = data->bs; + + data->ret = bdrv_co_is_allocated(bs, data->sector_num, data->nb_sectors, + data->pnum); + data->done = true; +} + +/* + * Synchronous wrapper around bdrv_co_is_allocated(). + * + * See bdrv_co_is_allocated() for details. + */ +int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, + int *pnum) +{ + Coroutine *co; + BdrvCoIsAllocatedData data = { + .bs = bs, + .sector_num = sector_num, + .nb_sectors = nb_sectors, + .pnum = pnum, + .done = false, + }; + + co = qemu_coroutine_create(bdrv_is_allocated_co_entry); + qemu_coroutine_enter(co, &data); + while (!data.done) { + qemu_aio_wait(); + } + return data.ret; } void bdrv_mon_event(const BlockDriverState *bdrv, @@ -1869,6 +2277,21 @@ BlockInfoList *qmp_query_block(Error **errp) info->value->inserted->has_backing_file = true; info->value->inserted->backing_file = g_strdup(bs->backing_file); } + + if (bs->io_limits_enabled) { + info->value->inserted->bps = + bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]; + info->value->inserted->bps_rd = + bs->io_limits.bps[BLOCK_IO_LIMIT_READ]; + info->value->inserted->bps_wr = + bs->io_limits.bps[BLOCK_IO_LIMIT_WRITE]; + info->value->inserted->iops = + bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]; + info->value->inserted->iops_rd = + bs->io_limits.iops[BLOCK_IO_LIMIT_READ]; + info->value->inserted->iops_wr = + bs->io_limits.iops[BLOCK_IO_LIMIT_WRITE]; + } } /* XXX: waiting for the qapi to support GSList */ @@ -2480,6 +2903,170 @@ void bdrv_aio_cancel(BlockDriverAIOCB *acb) acb->pool->cancel(acb); } +/* block I/O throttling */ +static bool bdrv_exceed_bps_limits(BlockDriverState *bs, int nb_sectors, + bool is_write, double elapsed_time, uint64_t *wait) +{ + uint64_t bps_limit = 0; + double bytes_limit, bytes_base, bytes_res; + double slice_time, wait_time; + + if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) { + bps_limit = bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]; + } else if (bs->io_limits.bps[is_write]) { + bps_limit = bs->io_limits.bps[is_write]; + } else { + if (wait) { + *wait = 0; + } + + return false; + } + + slice_time = bs->slice_end - bs->slice_start; + slice_time /= (NANOSECONDS_PER_SECOND); + bytes_limit = bps_limit * slice_time; + bytes_base = bs->nr_bytes[is_write] - bs->io_base.bytes[is_write]; + if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) { + bytes_base += bs->nr_bytes[!is_write] - bs->io_base.bytes[!is_write]; + } + + /* bytes_base: the bytes of data which have been read/written; and + * it is obtained from the history statistic info. + * bytes_res: the remaining bytes of data which need to be read/written. + * (bytes_base + bytes_res) / bps_limit: used to calcuate + * the total time for completing reading/writting all data. + */ + bytes_res = (unsigned) nb_sectors * BDRV_SECTOR_SIZE; + + if (bytes_base + bytes_res <= bytes_limit) { + if (wait) { + *wait = 0; + } + + return false; + } + + /* Calc approx time to dispatch */ + wait_time = (bytes_base + bytes_res) / bps_limit - elapsed_time; + + /* When the I/O rate at runtime exceeds the limits, + * bs->slice_end need to be extended in order that the current statistic + * info can be kept until the timer fire, so it is increased and tuned + * based on the result of experiment. + */ + bs->slice_time = wait_time * BLOCK_IO_SLICE_TIME * 10; + bs->slice_end += bs->slice_time - 3 * BLOCK_IO_SLICE_TIME; + if (wait) { + *wait = wait_time * BLOCK_IO_SLICE_TIME * 10; + } + + return true; +} + +static bool bdrv_exceed_iops_limits(BlockDriverState *bs, bool is_write, + double elapsed_time, uint64_t *wait) +{ + uint64_t iops_limit = 0; + double ios_limit, ios_base; + double slice_time, wait_time; + + if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) { + iops_limit = bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]; + } else if (bs->io_limits.iops[is_write]) { + iops_limit = bs->io_limits.iops[is_write]; + } else { + if (wait) { + *wait = 0; + } + + return false; + } + + slice_time = bs->slice_end - bs->slice_start; + slice_time /= (NANOSECONDS_PER_SECOND); + ios_limit = iops_limit * slice_time; + ios_base = bs->nr_ops[is_write] - bs->io_base.ios[is_write]; + if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) { + ios_base += bs->nr_ops[!is_write] - bs->io_base.ios[!is_write]; + } + + if (ios_base + 1 <= ios_limit) { + if (wait) { + *wait = 0; + } + + return false; + } + + /* Calc approx time to dispatch */ + wait_time = (ios_base + 1) / iops_limit; + if (wait_time > elapsed_time) { + wait_time = wait_time - elapsed_time; + } else { + wait_time = 0; + } + + bs->slice_time = wait_time * BLOCK_IO_SLICE_TIME * 10; + bs->slice_end += bs->slice_time - 3 * BLOCK_IO_SLICE_TIME; + if (wait) { + *wait = wait_time * BLOCK_IO_SLICE_TIME * 10; + } + + return true; +} + +static bool bdrv_exceed_io_limits(BlockDriverState *bs, int nb_sectors, + bool is_write, int64_t *wait) +{ + int64_t now, max_wait; + uint64_t bps_wait = 0, iops_wait = 0; + double elapsed_time; + int bps_ret, iops_ret; + + now = qemu_get_clock_ns(vm_clock); + if ((bs->slice_start < now) + && (bs->slice_end > now)) { + bs->slice_end = now + bs->slice_time; + } else { + bs->slice_time = 5 * BLOCK_IO_SLICE_TIME; + bs->slice_start = now; + bs->slice_end = now + bs->slice_time; + + bs->io_base.bytes[is_write] = bs->nr_bytes[is_write]; + bs->io_base.bytes[!is_write] = bs->nr_bytes[!is_write]; + + bs->io_base.ios[is_write] = bs->nr_ops[is_write]; + bs->io_base.ios[!is_write] = bs->nr_ops[!is_write]; + } + + elapsed_time = now - bs->slice_start; + elapsed_time /= (NANOSECONDS_PER_SECOND); + + bps_ret = bdrv_exceed_bps_limits(bs, nb_sectors, + is_write, elapsed_time, &bps_wait); + iops_ret = bdrv_exceed_iops_limits(bs, is_write, + elapsed_time, &iops_wait); + if (bps_ret || iops_ret) { + max_wait = bps_wait > iops_wait ? bps_wait : iops_wait; + if (wait) { + *wait = max_wait; + } + + now = qemu_get_clock_ns(vm_clock); + if (bs->slice_end < now + max_wait) { + bs->slice_end = now + max_wait; + } + + return true; + } + + if (wait) { + *wait = 0; + } + + return false; +} /**************************************************************/ /* async block device emulation */ |