aboutsummaryrefslogtreecommitdiff
path: root/block
diff options
context:
space:
mode:
authorFam Zheng <famz@redhat.com>2015-04-01 09:45:38 +0800
committerKevin Wolf <kwolf@redhat.com>2015-04-28 15:36:09 +0200
commite5e51dd3af6a0872dedce290ee41437b5aeed109 (patch)
treed5ff9a3ea2164c674e46831e1a11b4b13b7ca8cf /block
parent9eddd6a4b3b187ba50038800b6e4aeda4973b365 (diff)
downloadqemu-e5e51dd3af6a0872dedce290ee41437b5aeed109.zip
qemu-e5e51dd3af6a0872dedce290ee41437b5aeed109.tar.gz
qemu-e5e51dd3af6a0872dedce290ee41437b5aeed109.tar.bz2
block/null: Latency simulation by adding new option "latency-ns"
Aio context switch should just work because the requests will be drained, so the scheduled timer(s) on the old context will be freed. Signed-off-by: Fam Zheng <famz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1427852740-24315-2-git-send-email-famz@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/null.c58
1 files changed, 52 insertions, 6 deletions
diff --git a/block/null.c b/block/null.c
index ec2bd27..267d3e6 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;
}