On 01/23/2011 05:53 PM, Boaz Harrosh wrote:
>
> Since sg-read is a bidi operation, it is a gain to convert
> a single sg entry into a regular read. Better do this in the
> generic layer then force each caller to do so.
>
> Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
> ---
> drivers/scsi/osd/osd_initiator.c | 20 ++++++++++++++++----
> 1 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/osd/osd_initiator.c b/drivers/scsi/osd/osd_initiator.c
> index 0433ea6..19ddf65 100644
> --- a/drivers/scsi/osd/osd_initiator.c
> +++ b/drivers/scsi/osd/osd_initiator.c
> @@ -1005,11 +1005,23 @@ int osd_req_read_sg(struct osd_request *or,
> const struct osd_sg_entry *sglist, unsigned numentries)
> {
> u64 len;
> - int ret = _add_sg_continuation_descriptor(or, sglist, numentries, &len);
> + u64 off;
> + int ret;
>
> - if (ret)
> - return ret;
> - osd_req_read(or, obj, 0, bio, len);
> + if (numentries > 1) {
> + off = 0;
> + ret = _add_sg_continuation_descriptor(or, sglist, numentries,
> + &len);
> + if (ret)
> + return ret;
> + } else {
> + /* Optimize the case of single segment, read_sg is a
> + * bidi operation.
> + */
> + len = sglist->len;
> + off = sglist->offset;
> + }
> + osd_req_read(or, obj, off, bio, len);
>
> return 0;
> }
James please include this patch into scsi-misc for the next merge window.
Thanks
Boaz
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