Re: [PATCH 5/6] block/block-copy: add memory limit

[Max Reitz <mreitz@redhat.com>]

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On 03.10.19 19:15, Vladimir Sementsov-Ogievskiy wrote:
> Currently total allocation for parallel requests to block-copy instance
> is unlimited. Let's limit it to 128 MiB.
> 
> For now block-copy is used only in backup, so actually we limit total
> allocation for backup job.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  include/block/block-copy.h | 3 +++
>  block/block-copy.c         | 5 +++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/include/block/block-copy.h b/include/block/block-copy.h
> index e2e135ff1b..bb666e7068 100644
> --- a/include/block/block-copy.h
> +++ b/include/block/block-copy.h
> @@ -16,6 +16,7 @@
>  #define BLOCK_COPY_H
>  
>  #include "block/block.h"
> +#include "qemu/co-shared-amount.h"
>  
>  typedef struct BlockCopyInFlightReq {
>      int64_t start_byte;
> @@ -69,6 +70,8 @@ typedef struct BlockCopyState {
>       */
>      ProgressResetCallbackFunc progress_reset_callback;
>      void *progress_opaque;
> +
> +    QemuCoSharedAmount *mem;
>  } BlockCopyState;
>  
>  BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
> diff --git a/block/block-copy.c b/block/block-copy.c
> index cc49d2345d..e700c20d0f 100644
> --- a/block/block-copy.c
> +++ b/block/block-copy.c
> @@ -21,6 +21,7 @@
>  #include "qemu/units.h"
>  
>  #define BLOCK_COPY_MAX_COPY_RANGE (16 * MiB)
> +#define BLOCK_COPY_MAX_MEM (128 * MiB)
>  
>  static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s,
>                                                         int64_t start,
> @@ -64,6 +65,7 @@ void block_copy_state_free(BlockCopyState *s)
>      }
>  
>      bdrv_release_dirty_bitmap(s->source->bs, s->copy_bitmap);
> +    qemu_co_shared_amount_free(s->mem);
>      g_free(s);
>  }
>  
> @@ -95,6 +97,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
>          .cluster_size = cluster_size,
>          .len = bdrv_dirty_bitmap_size(copy_bitmap),
>          .write_flags = write_flags,
> +        .mem = qemu_co_shared_amount_new(BLOCK_COPY_MAX_MEM),
>      };
>  
>      s->copy_range_size = QEMU_ALIGN_DOWN(max_transfer, cluster_size),
> @@ -316,7 +319,9 @@ int coroutine_fn block_copy(BlockCopyState *s,
>  
>          bdrv_reset_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);
>  
> +        qemu_co_get_amount(s->mem, chunk_end - start);

Now that I see it like this, maybe the name is too short.  This sounds
like it was trying to get some amount of coroutines.

Would “qemu_co_get_from_shared_amount” be too long?  (Something like
qemu_co_sham_alloc() would be funny, but maybe not.  :-)  Or maybe
exactly because it”s funny.)

Max

>          ret = block_copy_do_copy(s, start, chunk_end, error_is_read);
> +        qemu_co_put_amount(s->mem, chunk_end - start);
>          if (ret < 0) {
>              bdrv_set_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);
>              break;
> 



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