Re: [Xen-devel] [PATCH RFC 09/12] xen-blkback: move pending handles list from blkbk to pending_req

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.02.13 at 11:28, Roger Pau Monne <roger.pau@xxxxxxxxxx> wrote:
> Moving grant ref handles from blkbk to pending_req will allow us to
> get rid of the shared blkbk structure.

At the expense of (slightly?) higher memory requirements?

> --- a/drivers/block/xen-blkback/blkback.c
> +++ b/drivers/block/xen-blkback/blkback.c
> @@ -136,6 +136,7 @@ struct pending_req {
>       struct list_head        free_list;
>       struct persistent_gnt   
> *persistent_gnts[BLKIF_MAX_SEGMENTS_PER_REQUEST];
>       struct page             *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
> +     grant_handle_t          grant_handles[BLKIF_MAX_SEGMENTS_PER_REQUEST];

Adding yet another array here makes it even more desirable to
switch from multiple arrays to a singly array of a structure, thus
improving locality of the memory accesses involved in processing
an individual segment.

Jan


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