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Re: [Qemu-devel] [PATCH V3 for-1.6 2/5] block: Modify the throttling cod
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH V3 for-1.6 2/5] block: Modify the throttling code to implement the leaky bucket algorithm. |
Date: |
Fri, 26 Jul 2013 11:40:38 +0800 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, 07/23 18:29, Benoît Canet wrote:
> This patch replace the previous algorithm by the well described leaky bucket
> algorithm: A bucket is filled by the incoming IOs and a periodic timer
> decrement
> the counter to make the bucket leak. When a given threshold is reached the
> bucket is full and the IOs are hold.
>
> In this patch the threshold is set to a default value to make the code behave
> like the previous implementation.
>
> In the next patch the threshold will be exposed in QMP to let the user control
> the burstiness of the throttling.
>
> Signed-off-by: Benoit Canet <address@hidden>
> ---
> block.c | 454
> +++++++++++++++++++++++++++------------------
> blockdev.c | 71 +++++--
> include/block/block_int.h | 15 +-
> 3 files changed, 339 insertions(+), 201 deletions(-)
>
> diff --git a/block.c b/block.c
> index dc72643..f1cd9c0 100644
> --- a/block.c
> +++ b/block.c
> @@ -86,13 +86,6 @@ static void coroutine_fn bdrv_co_do_rw(void *opaque);
> static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
> int64_t sector_num, int nb_sectors);
>
> -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);
>
> @@ -101,6 +94,8 @@ static QLIST_HEAD(, BlockDriver) bdrv_drivers =
>
> /* If non-zero, use only whitelisted block drivers */
> static int use_bdrv_whitelist;
> +/* boolean used to inform the throttling code that a bdrv_drain_all is
> issued */
> +static bool draining;
>
> #ifdef _WIN32
> static int is_windows_drive_prefix(const char *filename)
> @@ -129,28 +124,170 @@ void bdrv_io_limits_disable(BlockDriverState *bs)
>
> while (qemu_co_enter_next(&bs->throttled_reqs)) {
> }
> +}
>
> - if (bs->block_timer) {
> - qemu_del_timer(bs->block_timer);
> - qemu_free_timer(bs->block_timer);
> - bs->block_timer = NULL;
> +static void bdrv_make_bps_buckets_leak(BlockDriverState *bs, int64_t delta)
> +{
> + int64_t *bytes = bs->leaky_buckets.bytes;
> + int64_t read_leak, write_leak;
> +
> + /* the limit apply to both reads and writes */
> + if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) {
> + /* compute half the total leak */
> + int64_t leak = ((bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL] * delta) /
> + NANOSECONDS_PER_SECOND);
> + int remain = leak % 2;
> + leak /= 2;
> +
> + /* the read bucket is smaller than half the quantity to leak so take
> + * care adding the leak difference to write leak
> + */
> + if (bytes[BLOCK_IO_LIMIT_READ] <= leak) {
> + read_leak = bytes[BLOCK_IO_LIMIT_READ];
> + write_leak = 2 * leak + remain - bytes[BLOCK_IO_LIMIT_READ];
> + /* symetric case */
> + } else if (bytes[BLOCK_IO_LIMIT_WRITE] <= leak) {
> + write_leak = bytes[BLOCK_IO_LIMIT_WRITE];
> + read_leak = 2 * leak + remain - bytes[BLOCK_IO_LIMIT_WRITE];
> + /* both bucket above leak count use half the total leak for both */
> + } else {
> + write_leak = leak;
> + read_leak = leak + remain;
> + }
> + /* else we consider that limits are separated */
> + } else {
> + read_leak = (bs->io_limits.bps[BLOCK_IO_LIMIT_READ] * delta) /
> + NANOSECONDS_PER_SECOND;
> + write_leak = (bs->io_limits.bps[BLOCK_IO_LIMIT_WRITE] * delta) /
> + NANOSECONDS_PER_SECOND;
> + }
> +
> + /* make the buckets leak */
> + bytes[BLOCK_IO_LIMIT_READ] = MAX(bytes[BLOCK_IO_LIMIT_READ] - read_leak,
> + 0);
> + bytes[BLOCK_IO_LIMIT_WRITE] = MAX(bytes[BLOCK_IO_LIMIT_WRITE] -
> write_leak,
> + 0);
> +}
> +
> +static void bdrv_make_iops_buckets_leak(BlockDriverState *bs, int64_t delta)
> +{
> + double *ios = bs->leaky_buckets.ios;
> + int64_t read_leak, write_leak;
> +
> + /* the limit apply to both reads and writes */
> + if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) {
> + /* compute half the total leak */
> + int64_t leak = ((bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL] * delta) /
> + NANOSECONDS_PER_SECOND);
You have the total leak here...
> + int remain = leak % 2;
> + leak /= 2;
> +
> + /* the read bucket is smaller than half the quantity to leak so take
> + * care adding the leak difference to write leak
> + */
> + if (ios[BLOCK_IO_LIMIT_READ] <= leak) {
> + read_leak = ios[BLOCK_IO_LIMIT_READ];
> + write_leak = 2 * leak + remain - ios[BLOCK_IO_LIMIT_READ];
> + /* symetric case */
> + } else if (ios[BLOCK_IO_LIMIT_WRITE] <= leak) {
> + write_leak = ios[BLOCK_IO_LIMIT_WRITE];
> + read_leak = 2 * leak + remain - ios[BLOCK_IO_LIMIT_WRITE];
> + /* both bucket above leak count use half the total leak for both */
> + } else {
> + write_leak = leak;
> + read_leak = leak + remain;
> + }
I think it is easier to understand written like this:
int64_t total_leak = ((bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL] *
delta) /
NANOSECONDS_PER_SECOND);
if (ios[BLOCK_IO_LIMIT_READ] <= total_leak / 2) {
read_leak = ios[BLOCK_IO_LIMIT_READ];
write_leak = total_leak - read_leak;
/* symetric case */
} else if (ios[BLOCK_IO_LIMIT_WRITE] <= total_leak / 2) {
write_leak = ios[BLOCK_IO_LIMIT_WRITE];
read_leak = total_leak - write_leak;
/* both bucket above leak count use half the total leak for both */
} else {
write_leak = total_leak / 2;
read_leak = (total_leak + 1) / 2;
}
> + /* else we consider that limits are separated */
> + } else {
> + read_leak = (bs->io_limits.iops[BLOCK_IO_LIMIT_READ] * delta) /
> + NANOSECONDS_PER_SECOND;
> + write_leak = (bs->io_limits.iops[BLOCK_IO_LIMIT_WRITE] * delta) /
> + NANOSECONDS_PER_SECOND;
> + }
> +
> + /* make the buckets leak */
> + ios[BLOCK_IO_LIMIT_READ] = MAX(ios[BLOCK_IO_LIMIT_READ] - read_leak, 0);
> + ios[BLOCK_IO_LIMIT_WRITE] = MAX(ios[BLOCK_IO_LIMIT_WRITE] - write_leak,
> 0);
> +}
> +
> +static void bdrv_leak_if_needed(BlockDriverState *bs)
> +{
> + int64_t now;
> + int64_t delta;
> +
> + if (!bs->must_leak) {
> + return;
> + }
> +
> + bs->must_leak = false;
> +
> + now = qemu_get_clock_ns(rt_clock);
> + delta = now - bs->previous_leak;
> + bs->previous_leak = now;
> +
> + bdrv_make_bps_buckets_leak(bs, delta);
> + bdrv_make_iops_buckets_leak(bs, delta);
> +}
> +
> +static void bdrv_block_timer_disable(BlockDriverState *bs)
> +{
> + if (!bs->block_timer) {
> + return;
> }
>
> - bs->slice_start = 0;
> - bs->slice_end = 0;
> + qemu_del_timer(bs->block_timer);
> + qemu_free_timer(bs->block_timer);
> + bs->block_timer = NULL;
> +}
> +
> +static bool bdrv_throttling_is_iddle(BlockDriverState *bs)
I don't quite understad the wording here, is iddle equivalent to idle?
> +{
> + int64_t delta = qemu_get_clock_ns(rt_clock) - bs->previous_leak;
> +
> + if (delta < BLOCK_IO_THROTTLE_PERIOD * 2) {
> + return false;
> + }
> +
> + /* iddle */
> + return true;
> }
>
> +/* This callback is the timer in charge of making the leaky buckets leak */
> static void bdrv_block_timer(void *opaque)
Will be more readable for me if you could rename it to
bdrv_clock_timer_cb.
> {
> BlockDriverState *bs = opaque;
>
> + /* disable throttling time on iddle for economy purpose */
> + if (bdrv_throttling_is_iddle(bs)) {
> + bdrv_block_timer_disable(bs);
> + return;
> + }
> +
> + /* rearm the timer */
> + qemu_mod_timer(bs->block_timer,
> + qemu_get_clock_ns(vm_clock) +
> + BLOCK_IO_THROTTLE_PERIOD);
> +
> + bs->must_leak = true;
> qemu_co_enter_next(&bs->throttled_reqs);
> }
>
> +static void bdrv_block_timer_enable(BlockDriverState *bs)
> +{
> + if (bs->block_timer) {
> + return;
> + }
> +
> + bs->block_timer = qemu_new_timer_ns(vm_clock, bdrv_block_timer, bs);
> + bs->previous_leak = qemu_get_clock_ns(rt_clock);
> + qemu_mod_timer(bs->block_timer,
> + qemu_get_clock_ns(vm_clock) +
> + BLOCK_IO_THROTTLE_PERIOD);
> +}
> +
> 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->io_limits_enabled = true;
> }
>
> @@ -165,15 +302,118 @@ bool bdrv_io_limits_enabled(BlockDriverState *bs)
> || io_limits->iops[BLOCK_IO_LIMIT_TOTAL];
> }
>
> +/* This function check if the correct bandwith threshold has been exceeded
What does the "correct bandwidth threshold" mean?
And s/bandwith/bandwidth/, series wide.
> + *
> + * @is_write: true if the current IO is a write, false if it's a read
> + * @ret: true if threshold has been exceeded else false
> + */
> +static bool bdrv_is_bps_threshold_exceeded(BlockDriverState *bs, bool
> is_write)
> +{
> + /* limit is on total read + write bps : do the sum and compare with total
> + * threshold
> + */
> + if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) {
> + int64_t bytes = bs->leaky_buckets.bytes[BLOCK_IO_LIMIT_READ] +
> + bs->leaky_buckets.bytes[BLOCK_IO_LIMIT_WRITE];
> + return bs->io_limits.bps_threshold[BLOCK_IO_LIMIT_TOTAL] < bytes;
> + }
> +
> + /* check wether the threshold corresponding to the current io type (read,
> + * write) has been exceeded
> + */
> + if (bs->io_limits.bps[is_write]) {
It looks dangerous to use is_write as index of the array.
> + return bs->io_limits.bps_threshold[is_write] <
> + bs->leaky_buckets.bytes[is_write];
> + }
> +
> + /* no limit */
> + return false;
> +}
> +
> +/* This function check if the correct iops threshold has been exceeded
> + *
> + * @is_write: true if the current IO is a write, false if it's a read
> + * @ret: true if threshold has been exceeded else false
> + */
> +static bool bdrv_is_iops_threshold_exceeded(BlockDriverState *bs, bool
> is_write)
> +{
> + /* limit is on total read + write iops : do the sum and compare with
> total
> + * threshold
> + */
> + if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) {
> + double ios = bs->leaky_buckets.ios[BLOCK_IO_LIMIT_READ] +
> + bs->leaky_buckets.ios[BLOCK_IO_LIMIT_WRITE];
> + return bs->io_limits.iops_threshold[BLOCK_IO_LIMIT_TOTAL] < ios;
> + }
> +
> + /* check wether the threshold corresponding to the current io type (read,
> + * write) has been exceeded
> + */
> + if (bs->io_limits.iops[is_write]) {
> + return bs->io_limits.iops_threshold[is_write] <
> + bs->leaky_buckets.ios[is_write];
> + }
> +
> + /* no limit */
> + return false;
> +}
> +
> +/* This function check if any bandwith or iops threshold has been exceeded
> + *
> + * @nb_sectors: the number of sectors of the current IO
> + * @is_write: true if the current IO is a write, false if it's a read
> + * @ret: true if any threshold has been exceeded else false
> + */
> +static bool bdrv_is_any_threshold_exceeded(BlockDriverState *bs, int
> nb_sectors,
> + bool is_write)
> +{
> + bool bps_ret, iops_ret;
> +
> + /* check if any bandwith or per IO threshold has been exceeded */
> + bps_ret = bdrv_is_bps_threshold_exceeded(bs, is_write);
> + iops_ret = bdrv_is_iops_threshold_exceeded(bs, is_write);
> +
> + /* if so the IO will be blocked so do not account it and return true
> + * also return false if a bdrv_drain_all is in progress
> + */
> + if (!draining && (bps_ret || iops_ret)) {
> + return true;
> + }
> +
> + /* NOTE: the counter can go above the threshold when authorizing an IO.
> + * At next call the code will punish the guest by blocking the
> + * next IO until the counter has been decremented below the
> threshold.
> + * This way if a guest issue a jumbo IO bigger than the threshold
> it
> + * will have a chance no be authorized and will not result in a
> guest
> + * IO deadlock.
> + */
> +
> + /* the IO is authorized so do the accounting and return false */
> + bs->leaky_buckets.bytes[is_write] += (int64_t)nb_sectors *
> + BDRV_SECTOR_SIZE;
> + bs->leaky_buckets.ios[is_write]++;
> +
> + return false;
> +}
> +
> static void bdrv_io_limits_intercept(BlockDriverState *bs,
> bool is_write, int nb_sectors)
> {
> - int64_t wait_time = -1;
> + /* enable block timer if needed when intercepting I/Os */
> + if (!bs->block_timer) {
Already checking for bs->block_timer in bdrv_block_timer_enable().
> + bdrv_block_timer_enable(bs);
> + }
>
> + bdrv_leak_if_needed(bs);
> + /* if some IOs are already queued because the bucket is full put the
> current
> + * IO at the end of the queue (FIFO)
> + */
> if (!qemu_co_queue_empty(&bs->throttled_reqs)) {
> qemu_co_queue_wait(&bs->throttled_reqs);
> }
>
> + bdrv_leak_if_needed(bs);
> +
> /* 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
> @@ -181,13 +421,19 @@ static void bdrv_io_limits_intercept(BlockDriverState
> *bs,
> * 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));
> + /* if a threshold is exceeded the leaky bucket is full so the code put
> the
> + * IO in the throttle_reqs queue until the bucket has leaked enough to be
> + * not full
> + */
> + while (bdrv_is_any_threshold_exceeded(bs, nb_sectors, is_write)) {
> + bdrv_leak_if_needed(bs);
> qemu_co_queue_wait_insert_head(&bs->throttled_reqs);
> + bdrv_leak_if_needed(bs);
> }
>
> + bdrv_leak_if_needed(bs);
> qemu_co_queue_next(&bs->throttled_reqs);
> + bdrv_leak_if_needed(bs);
> }
>
> /* check if the path starts with "<protocol>:" */
> @@ -1439,6 +1685,9 @@ void bdrv_drain_all(void)
> BlockDriverState *bs;
> bool busy;
>
> + /* tell the throttling code we are draining */
> + draining = true;
> +
> do {
> busy = qemu_aio_wait();
>
> @@ -1457,6 +1706,8 @@ void bdrv_drain_all(void)
> assert(QLIST_EMPTY(&bs->tracked_requests));
> assert(qemu_co_queue_empty(&bs->throttled_reqs));
> }
> +
> + draining = false;
> }
>
> /* make a BlockDriverState anonymous by removing from bdrv_state list.
> @@ -1492,9 +1743,7 @@ static void bdrv_move_feature_fields(BlockDriverState
> *bs_dest,
> bs_dest->enable_write_cache = bs_src->enable_write_cache;
>
> /* i/o timing parameters */
> - bs_dest->slice_start = bs_src->slice_start;
> - bs_dest->slice_end = bs_src->slice_end;
> - bs_dest->slice_submitted = bs_src->slice_submitted;
> + bs_dest->leaky_buckets = bs_src->leaky_buckets;
> bs_dest->io_limits = bs_src->io_limits;
> bs_dest->throttled_reqs = bs_src->throttled_reqs;
> bs_dest->block_timer = bs_src->block_timer;
> @@ -3551,169 +3800,6 @@ void bdrv_aio_cancel(BlockDriverAIOCB *acb)
> acb->aiocb_info->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;
> - uint64_t extension;
> - 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->slice_submitted.bytes[is_write];
> - if (bs->io_limits.bps[BLOCK_IO_LIMIT_TOTAL]) {
> - bytes_base += bs->slice_submitted.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.
> - */
> - extension = wait_time * NANOSECONDS_PER_SECOND;
> - extension = DIV_ROUND_UP(extension, BLOCK_IO_SLICE_TIME) *
> - BLOCK_IO_SLICE_TIME;
> - bs->slice_end += extension;
> - if (wait) {
> - *wait = wait_time * NANOSECONDS_PER_SECOND;
> - }
> -
> - 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->slice_submitted.ios[is_write];
> - if (bs->io_limits.iops[BLOCK_IO_LIMIT_TOTAL]) {
> - ios_base += bs->slice_submitted.ios[!is_write];
> - }
> -
> - if (ios_base + 1 <= ios_limit) {
> - if (wait) {
> - *wait = 0;
> - }
> -
> - return false;
> - }
> -
> - /* Calc approx time to dispatch, in seconds */
> - wait_time = (ios_base + 1) / iops_limit;
> - if (wait_time > elapsed_time) {
> - wait_time = wait_time - elapsed_time;
> - } else {
> - wait_time = 0;
> - }
> -
> - /* Exceeded current slice, extend it by another slice time */
> - bs->slice_end += BLOCK_IO_SLICE_TIME;
> - if (wait) {
> - *wait = wait_time * NANOSECONDS_PER_SECOND;
> - }
> -
> - 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 (now > bs->slice_end) {
> - bs->slice_start = now;
> - bs->slice_end = now + BLOCK_IO_SLICE_TIME;
> - memset(&bs->slice_submitted, 0, sizeof(bs->slice_submitted));
> - }
> -
> - 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;
> - }
> -
> - bs->slice_submitted.bytes[is_write] += (int64_t)nb_sectors *
> - BDRV_SECTOR_SIZE;
> - bs->slice_submitted.ios[is_write]++;
> -
> - return false;
> -}
> -
> /**************************************************************/
> /* async block device emulation */
>
> diff --git a/blockdev.c b/blockdev.c
> index c5abd65..491e4d0 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -280,10 +280,25 @@ static int parse_block_error_action(const char *buf,
> bool is_read)
> }
> }
>
> +static bool check_io_limit(int64_t limit)
> +{
> + if (!limit) {
> + return false;
> + }
> +
> + if (limit < (THROTTLE_HZ * 2)) {
> + return true;
> + }
> +
> + return false;
> +}
> +
> static bool do_check_io_limits(BlockIOLimit *io_limits, Error **errp)
> {
> bool bps_flag;
> bool iops_flag;
> + bool bps_threshold_flag;
> + bool iops_threshold_flag;
>
> assert(io_limits);
>
> @@ -299,13 +314,30 @@ static bool do_check_io_limits(BlockIOLimit *io_limits,
> Error **errp)
> return false;
> }
>
> - if (io_limits->bps[BLOCK_IO_LIMIT_TOTAL] < 0 ||
> - io_limits->bps[BLOCK_IO_LIMIT_WRITE] < 0 ||
> - io_limits->bps[BLOCK_IO_LIMIT_READ] < 0 ||
> - io_limits->iops[BLOCK_IO_LIMIT_TOTAL] < 0 ||
> - io_limits->iops[BLOCK_IO_LIMIT_WRITE] < 0 ||
> - io_limits->iops[BLOCK_IO_LIMIT_READ] < 0) {
> - error_setg(errp, "bps and iops values must be 0 or greater");
> + bps_threshold_flag =
> + (io_limits->bps_threshold[BLOCK_IO_LIMIT_TOTAL] != 0)
> + && ((io_limits->bps_threshold[BLOCK_IO_LIMIT_READ] != 0)
> + || (io_limits->bps_threshold[BLOCK_IO_LIMIT_WRITE] != 0));
> + iops_threshold_flag =
> + (io_limits->iops_threshold[BLOCK_IO_LIMIT_TOTAL] != 0)
> + && ((io_limits->iops_threshold[BLOCK_IO_LIMIT_READ] != 0)
> + || (io_limits->iops_threshold[BLOCK_IO_LIMIT_WRITE] != 0));
> + if (bps_threshold_flag || iops_threshold_flag) {
> + error_setg(errp, "bps_threshold(iops_threshold) and "
> + "bps_rd_threshold/bps_wr_threshold"
> + "(iops_rd_threshold/iops_wr_threshold) "
> + "cannot be used at the same time");
> + return false;
> + }
> +
> + if (check_io_limit(io_limits->bps[BLOCK_IO_LIMIT_TOTAL]) ||
> + check_io_limit(io_limits->bps[BLOCK_IO_LIMIT_WRITE]) ||
> + check_io_limit(io_limits->bps[BLOCK_IO_LIMIT_READ]) ||
> + check_io_limit(io_limits->iops[BLOCK_IO_LIMIT_TOTAL]) ||
> + check_io_limit(io_limits->iops[BLOCK_IO_LIMIT_WRITE]) ||
> + check_io_limit(io_limits->iops[BLOCK_IO_LIMIT_READ])) {
> + error_setg(errp, "bps and iops values must be %i or greater",
> + THROTTLE_HZ * 2);
> return false;
> }
>
> @@ -497,6 +529,18 @@ DriveInfo *drive_init(QemuOpts *all_opts,
> BlockInterfaceType block_default_type)
> qemu_opt_get_number(opts, "iops_rd", 0);
> io_limits.iops[BLOCK_IO_LIMIT_WRITE] =
> qemu_opt_get_number(opts, "iops_wr", 0);
> + io_limits.bps_threshold[BLOCK_IO_LIMIT_TOTAL] =
> + io_limits.bps[BLOCK_IO_LIMIT_TOTAL] / THROTTLE_HZ;
> + io_limits.bps_threshold[BLOCK_IO_LIMIT_READ] =
> + io_limits.bps[BLOCK_IO_LIMIT_READ] / THROTTLE_HZ;
> + io_limits.bps_threshold[BLOCK_IO_LIMIT_WRITE] =
> + io_limits.bps[BLOCK_IO_LIMIT_WRITE] / THROTTLE_HZ;
> + io_limits.iops_threshold[BLOCK_IO_LIMIT_TOTAL] =
> + io_limits.iops[BLOCK_IO_LIMIT_TOTAL] /
> THROTTLE_HZ;
> + io_limits.iops_threshold[BLOCK_IO_LIMIT_READ] =
> + io_limits.iops[BLOCK_IO_LIMIT_READ] / THROTTLE_HZ;
> + io_limits.iops_threshold[BLOCK_IO_LIMIT_WRITE] =
> + io_limits.iops[BLOCK_IO_LIMIT_WRITE] /
> THROTTLE_HZ;
>
> if (!do_check_io_limits(&io_limits, &error)) {
> error_report("%s", error_get_pretty(error));
> @@ -1198,6 +1242,12 @@ void qmp_block_set_io_throttle(const char *device,
> int64_t bps, int64_t bps_rd,
> io_limits.iops[BLOCK_IO_LIMIT_TOTAL]= iops;
> io_limits.iops[BLOCK_IO_LIMIT_READ] = iops_rd;
> io_limits.iops[BLOCK_IO_LIMIT_WRITE]= iops_wr;
> + io_limits.bps_threshold[BLOCK_IO_LIMIT_TOTAL] = bps / THROTTLE_HZ;
> + io_limits.bps_threshold[BLOCK_IO_LIMIT_READ] = bps_rd / THROTTLE_HZ;
> + io_limits.bps_threshold[BLOCK_IO_LIMIT_WRITE] = bps_wr / THROTTLE_HZ;
> + io_limits.iops_threshold[BLOCK_IO_LIMIT_TOTAL] = iops / THROTTLE_HZ;
> + io_limits.iops_threshold[BLOCK_IO_LIMIT_READ] = iops_rd / THROTTLE_HZ;
> + io_limits.iops_threshold[BLOCK_IO_LIMIT_WRITE] = iops_wr / THROTTLE_HZ;
>
> if (!do_check_io_limits(&io_limits, errp)) {
> return;
> @@ -1209,11 +1259,10 @@ void qmp_block_set_io_throttle(const char *device,
> int64_t bps, int64_t bps_rd,
> bdrv_io_limits_enable(bs);
> } else if (bs->io_limits_enabled && !bdrv_io_limits_enabled(bs)) {
> bdrv_io_limits_disable(bs);
> - } else {
> - if (bs->block_timer) {
> - qemu_mod_timer(bs->block_timer, qemu_get_clock_ns(vm_clock));
> - }
> }
> +
> + /* reset leaky bucket to get the system in a known state */
> + memset(&bs->leaky_buckets, 0, sizeof(bs->leaky_buckets));
> }
>
> int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index c6ac871..e32ad1f 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -43,8 +43,9 @@
> #define BLOCK_IO_LIMIT_WRITE 1
> #define BLOCK_IO_LIMIT_TOTAL 2
>
> -#define BLOCK_IO_SLICE_TIME 100000000
> #define NANOSECONDS_PER_SECOND 1000000000.0
> +#define THROTTLE_HZ 1
> +#define BLOCK_IO_THROTTLE_PERIOD (NANOSECONDS_PER_SECOND / THROTTLE_HZ)
>
> #define BLOCK_OPT_SIZE "size"
> #define BLOCK_OPT_ENCRYPT "encryption"
> @@ -73,11 +74,13 @@ typedef struct BdrvTrackedRequest {
> typedef struct BlockIOLimit {
> int64_t bps[3];
> int64_t iops[3];
> + int64_t bps_threshold[3];
> + int64_t iops_threshold[3];
> } BlockIOLimit;
>
> typedef struct BlockIOBaseValue {
> - uint64_t bytes[2];
> - uint64_t ios[2];
> + int64_t bytes[2];
> + double ios[2];
> } BlockIOBaseValue;
>
> struct BlockDriver {
> @@ -264,10 +267,10 @@ struct BlockDriverState {
> unsigned int copy_on_read_in_flight;
>
> /* the time for latest disk I/O */
> - int64_t slice_start;
> - int64_t slice_end;
> BlockIOLimit io_limits;
> - BlockIOBaseValue slice_submitted;
> + BlockIOBaseValue leaky_buckets;
> + int64_t previous_leak;
> + bool must_leak;
> CoQueue throttled_reqs;
> QEMUTimer *block_timer;
> bool io_limits_enabled;
> --
> 1.7.10.4
>
>
--
Fam
- [Qemu-devel] [PATCH V3 for-1.6 0/5] Leaky bucket throttling and features, Benoît Canet, 2013/07/23
- [Qemu-devel] [PATCH V3 for-1.6 1/5] block: Repair the throttling code., Benoît Canet, 2013/07/23
- [Qemu-devel] [PATCH V3 for-1.6 3/5] block: Add support for throttling burst threshold in QMP and the co mmand line., Benoît Canet, 2013/07/23
- [Qemu-devel] [PATCH V3 for-1.6 2/5] block: Modify the throttling code to implement the leaky bucket algorithm., Benoît Canet, 2013/07/23
- Re: [Qemu-devel] [PATCH V3 for-1.6 2/5] block: Modify the throttling code to implement the leaky bucket algorithm.,
Fam Zheng <=
- [Qemu-devel] [PATCH V3 for-1.6 4/5] block: Add iops_sector_count to do the iops accounting for a gi ven io size., Benoît Canet, 2013/07/23
- [Qemu-devel] [PATCH V3 for-1.6 5/5] block: Add throttling percentage metrics., Benoît Canet, 2013/07/23
- Re: [Qemu-devel] [PATCH V3 for-1.6 0/5] Leaky bucket throttling and features, Fam Zheng, 2013/07/25
- Re: [Qemu-devel] [PATCH V3 for-1.6 0/5] Leaky bucket throttling and features, Eric Blake, 2013/07/26