Re: [Qemu-devel] [PATCH] block/iscsi: allow cluster_size of 4K and greater

[Eric Blake]

On 04/28/2014 09:18 AM, Peter Lieven wrote:
> depending on the target the opt_unmap_gran might be as low
> as 4K. As we know use this also as a knob to activate the allocationmap

s/know/now/

> feature lower the barrier. The limit 4K (and not 512) is choosen
> to avoid a potentially too big allocationmap.
> 
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  block/iscsi.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index eca8a22..944f2ce 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -1377,7 +1377,7 @@ static int iscsi_open(BlockDriverState *bs, QDict 
> *options, int flags,
>      /* Guess the internal cluster (page) size of the iscsi target by the 
> means
>       * of opt_unmap_gran. Transfer the unmap granularity only if it has a
>       * reasonable size */
> -    if (iscsilun->bl.opt_unmap_gran * iscsilun->block_size >= 64 * 1024 &&
> +    if (iscsilun->bl.opt_unmap_gran * iscsilun->block_size >= 4 * 1024 &&
>          iscsilun->bl.opt_unmap_gran * iscsilun->block_size <= 16 * 1024 * 
> 1024) {
>          iscsilun->cluster_sectors = (iscsilun->bl.opt_unmap_gran *
>                                       iscsilun->block_size) >> 
> BDRV_SECTOR_BITS;
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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