On Thu, Jun 21, 2018 at 04:53:54PM +0300, Yishai Hadas wrote:
> On 6/20/2018 10:35 PM, Jason Gunthorpe wrote:
> >On Wed, Jun 20, 2018 at 07:28:22PM +0300, Yishai Hadas wrote:
> >>@@ -80,7 +80,16 @@ static int copy_to_scat(struct mlx5_wqe_data_seg *scat, void *buf, int *size,
> >> for (i = 0; i < max; ++i) {
> >> copy = min_t(long, *size, be32toh(scat->byte_count));
> >>- memcpy((void *)(unsigned long)be64toh(scat->addr), buf, copy);
> >>+
> >>+ /* When NULL MR is used can't copy to target,
> >>+ * expected to be NULL.
> >>+ */
> >>+ if (unlikely(scat->lkey == ctx->dump_fill_mkey_be))
> >>+ ;
> >>+ else
> >
> >What is that? Better as:
> >
> >if (likely(scat->lkey != ctx->dump_fill_mkey_be))
> > memcpy((void *)(unsigned long)be64toh(scat->addr),
> > buf, copy);
> >
>
> This is data path flow, upon performance testing we found the unlikely
> variant to be better than this suggestion.
That is a highly compiler specific statement. I assume you tested this
with some ancient compiler?
IMHO you should stick to the sane code.
Jason
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