diff options
| -rw-r--r-- | block/null.c | 58 | ||||
| -rw-r--r-- | qapi/block-core.json | 5 |
2 files changed, 56 insertions, 7 deletions
diff --git a/block/null.c b/block/null.c index ec2bd27a4b..267d3e6ad9 100644 --- a/block/null.c +++ b/block/null.c @@ -12,8 +12,11 @@ #include "block/block_int.h" +#define NULL_OPT_LATENCY "latency-ns" + typedef struct { int64_t length; + int64_t latency_ns; } BDRVNullState; static QemuOptsList runtime_opts = { @@ -30,6 +33,12 @@ static QemuOptsList runtime_opts = { .type = QEMU_OPT_SIZE, .help = "size of the null block", }, + { + .name = NULL_OPT_LATENCY, + .type = QEMU_OPT_NUMBER, + .help = "nanoseconds (approximated) to wait " + "before completing request", + }, { /* end of list */ } }, }; @@ -39,13 +48,20 @@ static int null_file_open(BlockDriverState *bs, QDict *options, int flags, { QemuOpts *opts; BDRVNullState *s = bs->opaque; + int ret = 0; opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort); qemu_opts_absorb_qdict(opts, options, &error_abort); s->length = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30); + s->latency_ns = + qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0); + if (s->latency_ns < 0) { + error_setg(errp, "latency-ns is invalid"); + ret = -EINVAL; + } qemu_opts_del(opts); - return 0; + return ret; } static void null_close(BlockDriverState *bs) @@ -58,28 +74,40 @@ static int64_t null_getlength(BlockDriverState *bs) return s->length; } +static coroutine_fn int null_co_common(BlockDriverState *bs) +{ + BDRVNullState *s = bs->opaque; + + if (s->latency_ns) { + co_aio_sleep_ns(bdrv_get_aio_context(bs), QEMU_CLOCK_REALTIME, + s->latency_ns); + } + return 0; +} + static coroutine_fn int null_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { - return 0; + return null_co_common(bs); } static coroutine_fn int null_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { - return 0; + return null_co_common(bs); } static coroutine_fn int null_co_flush(BlockDriverState *bs) { - return 0; + return null_co_common(bs); } typedef struct { BlockAIOCB common; QEMUBH *bh; + QEMUTimer timer; } NullAIOCB; static const AIOCBInfo null_aiocb_info = { @@ -94,15 +122,33 @@ static void null_bh_cb(void *opaque) qemu_aio_unref(acb); } +static void null_timer_cb(void *opaque) +{ + NullAIOCB *acb = opaque; + acb->common.cb(acb->common.opaque, 0); + timer_deinit(&acb->timer); + qemu_aio_unref(acb); +} + static inline BlockAIOCB *null_aio_common(BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque) { NullAIOCB *acb; + BDRVNullState *s = bs->opaque; acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque); - acb->bh = aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); - qemu_bh_schedule(acb->bh); + /* Only emulate latency after vcpu is running. */ + if (s->latency_ns) { + aio_timer_init(bdrv_get_aio_context(bs), &acb->timer, + QEMU_CLOCK_REALTIME, SCALE_NS, + null_timer_cb, acb); + timer_mod_ns(&acb->timer, + qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns); + } else { + acb->bh = aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); + qemu_bh_schedule(acb->bh); + } return &acb->common; } diff --git a/qapi/block-core.json b/qapi/block-core.json index 78730846c2..e158a7cfc2 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -1310,11 +1310,14 @@ # Driver specific block device options for the null backend. # # @size: #optional size of the device in bytes. +# @latency-ns: #optional emulated latency (in nanoseconds) in processing +# requests. Default to zero which completes requests immediately. +# (Since 2.4) # # Since: 2.2 ## { 'type': 'BlockdevOptionsNull', - 'data': { '*size': 'int' } } + 'data': { '*size': 'int', '*latency-ns': 'uint64' } } ## # @BlockdevOptionsVVFAT |