|
| From: | Dr. David Alan Gilbert |
| Subject: | Re: [Qemu-devel] [PATCH 4/5] migration/block: limit the number of parallel I/O requests |
| Date: | Fri, 23 Mar 2018 16:45:45 +0000 |
| User-agent: | Mutt/1.9.2 (2017-12-15) |
* Peter Lieven (address@hidden) wrote:
> the current implementation submits up to 512 I/O requests in parallel
> which is much to high especially for a background task.
> This patch adds a maximum limit of 16 I/O requests that can
> be submitted in parallel to avoid monopolizing the I/O device.
>
> Signed-off-by: Peter Lieven <address@hidden>
Queued (including 5/5)
> ---
> migration/block.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/migration/block.c b/migration/block.c
> index 41b95d1..ce939e2 100644
> --- a/migration/block.c
> +++ b/migration/block.c
> @@ -37,6 +37,7 @@
> #define MAX_IS_ALLOCATED_SEARCH (65536 * BDRV_SECTOR_SIZE)
>
> #define MAX_IO_BUFFERS 512
> +#define MAX_PARALLEL_IO 16
>
> //#define DEBUG_BLK_MIGRATION
>
> @@ -775,6 +776,7 @@ static int block_save_iterate(QEMUFile *f, void *opaque)
> while ((block_mig_state.submitted +
> block_mig_state.read_done) * BLOCK_SIZE <
> qemu_file_get_rate_limit(f) &&
> + block_mig_state.submitted < MAX_PARALLEL_IO &&
> (block_mig_state.submitted + block_mig_state.read_done) <
> MAX_IO_BUFFERS) {
> blk_mig_unlock();
> --
> 2.7.4
>
>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
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