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

[Stefan Hajnoczi]

On Thu, Jul 28, 2011 at 6:43 AM, Zhi Yong Wu <address@hidden> wrote:
> On Wed, Jul 27, 2011 at 8:58 PM, Stefan Hajnoczi <address@hidden> wrote:
>> On Wed, Jul 27, 2011 at 11:17 AM, Zhi Yong Wu <address@hidden> wrote:
>>> On Wed, Jul 27, 2011 at 3:26 AM, Marcelo Tosatti <address@hidden> 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 <address@hidden>
>>>>> ---
>>>>>  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.
> Since I/O limits commands will depend on Supriya's block_set patch,
> when will her patch be merged into qemu.git?

The block_set patch is on the mailing list with an ongoing discussion.
 Until agreement is reached it will not be merged - hard to tell when
exactly that will be, but hopefully over the next few days.

You can always add temporary QMP/HMP commands in order to test setting
limits at runtime.  It should be easy to switch to a different QMP/HMP
command later, if necessary.

Stefan