Am 03.11.2011 09:57, schrieb Zhi Yong Wu:
> Signed-off-by: Zhi Yong Wu <wu...@linux.vnet.ibm.com>
> Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
> ---
> block.c | 220
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> block.h | 1 +
> block_int.h | 1 +
> 3 files changed, 222 insertions(+), 0 deletions(-)
>
> diff --git a/block.c b/block.c
> index 79e7f09..b2af48f 100644
> --- a/block.c
> +++ b/block.c
> @@ -74,6 +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);
>
> @@ -107,6 +114,24 @@ 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;
> @@ -136,6 +161,31 @@ bool bdrv_io_limits_enabled(BlockDriverState *bs)
> || 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)
> {
> @@ -718,6 +768,11 @@ 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:
> @@ -753,6 +808,11 @@ 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)
> @@ -1291,6 +1351,11 @@ static int coroutine_fn
> bdrv_co_do_readv(BlockDriverState *bs,
> return -EIO;
> }
>
> + /* throttling disk read I/O */
> + if (bs->io_limits_enabled) {
> + bdrv_io_limits_intercept(bs, false, nb_sectors);
> + }
> +
> return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
> }
>
> @@ -1321,6 +1386,11 @@ 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);
> + }
> +
> ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
>
> if (bs->dirty_bitmap) {
> @@ -2512,6 +2582,156 @@ 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_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;
> +
> + 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;
> + }
I'm not quire sure what bs->slice_end really is and what these
calculations do exactly. Looks like magic. Can you add some comments
that explain why slice_end is increased and how you estimate *wait?
> +
> + return true;
> +}
> +
> +static bool bdrv_exceed_iops_limits(BlockDriverState *bs, bool is_write,
> + double elapsed_time, uint64_t *wait) {
Coding style requires the brace on its own line.
> + 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) {
Same here.
Kevin
