Quoting r. Roland Dreier <[EMAIL PROTECTED]>:
> Subject: Re: [openib-general] [PATCH] (repost) no qp lock on poll, separate
> sq/rq locks
>
> Ugh, I think I missed something when I thought about this the first
> time around. It seems the test for WQ overflow assumes that all WQs
> have a power-of-2 size, which we currently don't enforce for Tavor
> mode.
Actually the old code had this
wq->last_comp = wq->max - 1;
which led me to assumed its a power of two.
> It seems there are two possible solutions:
>
> Round up WQ sizes for Tavor as well. I don't like this because it
> could potentially use a lot of extra memory.
>
> Or, add one more counter back into the WQ struct so we can keep
> track of both the next index to use as well as the total number of
> WQEs posted in Tavor mode (we still only need one counter in
> mem-free mode).
>
> I implemented the second option. Does this patch look reasonable?
>
> - R.
>
> Index: hw/mthca/mthca_provider.h
> ===================================================================
> --- hw/mthca/mthca_provider.h (revision 1912)
> +++ hw/mthca/mthca_provider.h (working copy)
> @@ -167,15 +167,16 @@ struct mthca_cq {
>
> struct mthca_wq {
> spinlock_t lock;
> - int max;
> - int next;
> - int last_comp;
> - void *last;
> - int max_gs;
> - int wqe_shift;
> + int max;
> + unsigned next_ind;
> + unsigned head;
> + unsigned tail;
> + void *last;
> + int max_gs;
> + int wqe_shift;
>
> - int db_index; /* Arbel only */
> - u32 *db;
> + int db_index; /* Arbel only */
> + u32 *db;
> };
>
> struct mthca_qp {
> Index: hw/mthca/mthca_cq.c
> ===================================================================
> --- hw/mthca/mthca_cq.c (revision 1912)
> +++ hw/mthca/mthca_cq.c (working copy)
> @@ -453,7 +453,7 @@ static inline int mthca_poll_one(struct
> entry->wr_id = (*cur_qp)->wrid[wqe_index];
> }
>
> - wq->last_comp = wqe_index;
> + ++wq->tail;
>
> if (0)
> mthca_dbg(dev, "%s completion for QP %06x, index %d (nr %d)\n",
You seem to assume that each completion is for exactly one wqe.
How does this work for selective signaling?
--
MST - Michael S. Tsirkin
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