Re: [Qemu-devel] [PATCH v2 1/1] The codes V2 for QEMU disk I/O limits.

[Stefan Hajnoczi <stefanha@gmail.com>]

On Wed, Jul 27, 2011 at 11:17 AM, Zhi Yong Wu <zwu.kernel@gmail.com> wrote:
> On Wed, Jul 27, 2011 at 3:26 AM, Marcelo Tosatti <mtosatti@redhat.com> wrote:
>> On Tue, Jul 26, 2011 at 04:59:06PM +0800, Zhi Yong Wu wrote:
>>> Welcome to give me your comments, thanks.
>>>
>>> Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
>>> ---
>>>  Makefile.objs     |    2 +-
>>>  block.c           |  288 +++++++++++++++++++++++++++++++++++++++++++++++++++--
>>>  block.h           |    1 -
>>>  block/blk-queue.c |  116 +++++++++++++++++++++
>>>  block/blk-queue.h |   70 +++++++++++++
>>>  block_int.h       |   28 +++++
>>>  blockdev.c        |   21 ++++
>>>  qemu-config.c     |   24 +++++
>>>  qemu-option.c     |   17 +++
>>>  qemu-option.h     |    1 +
>>>  qemu-options.hx   |    1 +
>>>  11 files changed, 559 insertions(+), 10 deletions(-)
>>>  create mode 100644 block/blk-queue.c
>>>  create mode 100644 block/blk-queue.h
>>>
>>> diff --git a/Makefile.objs b/Makefile.objs
>>> index 9f99ed4..06f2033 100644
>>> --- a/Makefile.objs
>>> +++ b/Makefile.objs
>>> @@ -23,7 +23,7 @@ block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vv
>>>  block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o
>>>  block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
>>>  block-nested-y += qed-check.o
>>> -block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
>>> +block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o blk-queue.o
>>>  block-nested-$(CONFIG_WIN32) += raw-win32.o
>>>  block-nested-$(CONFIG_POSIX) += raw-posix.o
>>>  block-nested-$(CONFIG_CURL) += curl.o
>>> diff --git a/block.c b/block.c
>>> index 24a25d5..e54e59c 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -29,6 +29,9 @@
>>>  #include "module.h"
>>>  #include "qemu-objects.h"
>>>
>>> +#include "qemu-timer.h"
>>> +#include "block/blk-queue.h"
>>> +
>>>  #ifdef CONFIG_BSD
>>>  #include <sys/types.h>
>>>  #include <sys/stat.h>
>>> @@ -58,6 +61,13 @@ static int bdrv_read_em(BlockDriverState *bs, int64_t sector_num,
>>>  static int bdrv_write_em(BlockDriverState *bs, int64_t sector_num,
>>>                           const uint8_t *buf, 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, uint64_t *wait);
>>> +
>>>  static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
>>>      QTAILQ_HEAD_INITIALIZER(bdrv_states);
>>>
>>> @@ -90,6 +100,20 @@ int is_windows_drive(const char *filename)
>>>  }
>>>  #endif
>>>
>>> +static int bdrv_io_limits_enable(BlockIOLimit *io_limits)
>>> +{
>>> +    if ((io_limits->bps[0] == 0)
>>> +         && (io_limits->bps[1] == 0)
>>> +         && (io_limits->bps[2] == 0)
>>> +         && (io_limits->iops[0] == 0)
>>> +         && (io_limits->iops[1] == 0)
>>> +         && (io_limits->iops[2] == 0)) {
>>> +        return 0;
>>> +    }
>>> +
>>> +    return 1;
>>> +}
>>> +
>>>  /* check if the path starts with "<protocol>:" */
>>>  static int path_has_protocol(const char *path)
>>>  {
>>> @@ -167,6 +191,28 @@ void path_combine(char *dest, int dest_size,
>>>      }
>>>  }
>>>
>>> +static void bdrv_block_timer(void *opaque)
>>> +{
>>> +    BlockDriverState *bs = opaque;
>>> +    BlockQueue *queue = bs->block_queue;
>>> +
>>> +    while (!QTAILQ_EMPTY(&queue->requests)) {
>>> +        BlockIORequest *request;
>>> +        int ret;
>>> +
>>> +        request = QTAILQ_FIRST(&queue->requests);
>>> +        QTAILQ_REMOVE(&queue->requests, request, entry);
>>> +
>>> +        ret = qemu_block_queue_handler(request);
>>> +        if (ret == 0) {
>>> +            QTAILQ_INSERT_HEAD(&queue->requests, request, entry);
>>> +            break;
>>> +        }
>>> +
>>> +        qemu_free(request);
>>> +    }
>>> +}
>>> +
>>>  void bdrv_register(BlockDriver *bdrv)
>>>  {
>>>      if (!bdrv->bdrv_aio_readv) {
>>> @@ -642,6 +688,15 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
>>>              bs->change_cb(bs->change_opaque, CHANGE_MEDIA);
>>>      }
>>>
>>> +    /* throttling disk I/O limits */
>>> +    if (bdrv_io_limits_enable(&bs->io_limits)) {
>>> +        bs->block_queue = qemu_new_block_queue();
>>> +        bs->block_timer = qemu_new_timer_ns(vm_clock, bdrv_block_timer, bs);
>>> +
>>> +        bs->slice_start[0] = qemu_get_clock_ns(vm_clock);
>>> +        bs->slice_start[1] = qemu_get_clock_ns(vm_clock);
>>> +    }
>>> +
>>
>> It should be possible to tune the limits on the flight, please introduce
>> QMP commands for that.
> Yeah, I am working on this.

It's worth mentioning that the I/O limits commands can use Supriya's
new block_set command for changing block device parameters at runtime.
 So I think the runtime limits changing can be a separate patch.

Stefan