[ofa-general] [PATCH] libmlx4: Re-calculate number of inline segments

[Roland Dreier]

 > Supplying an ibv_qp_cap.max_inline_data value of 460 for mlx4_create_qp
 > was getting back ENOMEM when the max should have been 928. Tracked the bug
 > to the inline segment calculation. Here's the fix.

I don't see what's wrong with the current code, or why your change is
anything but a more obfuscated way of calculating the same thing.  And
indeed, I just adapted a quick test program (below) which tries to
create QPs with max_inline_data of 460, and I get the results:

  RC: inline 460 ok (got 928)
  UC: inline 460 ok (got 928)
  UD: inline 460 ok (got 900)

so it seems to work on my system.

 - R.

Here's the test code:

#include <stdio.h>
#include <string.h>

#include <infiniband/verbs.h>

int main(int argc, char *argv)
{
	struct ibv_device      **dev_list;
	struct ibv_device_attr	 dev_attr;
	struct ibv_context	*context;
	struct ibv_pd		*pd;
	struct ibv_cq		*cq;
	struct ibv_qp_init_attr  qp_attr;
	int			 t;
	static const struct {
		enum ibv_qp_type type;
		char		*name;
	}			 type_tab[] = {
		{ IBV_QPT_RC, "RC" },
		{ IBV_QPT_UC, "UC" },
		{ IBV_QPT_UD, "UD" },
	};

	dev_list = ibv_get_device_list(NULL);
	if (!dev_list) {
		printf("No IB devices found\n");
		return 1;
	}

	for (; *dev_list; ++dev_list) {
		printf("%s:\n", ibv_get_device_name(*dev_list));

		context = ibv_open_device(*dev_list);
		if (!context) {
			printf("  ibv_open_device failed\n");
			continue;
		}

		if (ibv_query_device(context, &dev_attr)) {
			printf("  ibv_query_device failed\n");
			continue;
		}

		cq = ibv_create_cq(context, 1, NULL, NULL, 0);
		if (!cq) {
			printf("  ibv_create_cq failed\n");
			continue;
		}

		pd = ibv_alloc_pd(context);
		if (!pd) {
			printf("  ibv_alloc_pd failed\n");
			continue;
		}

		for (t = 0; t < sizeof type_tab / sizeof type_tab[0]; ++t) {
			memset(&qp_attr, 0, sizeof qp_attr);

			qp_attr.send_cq = cq;
			qp_attr.recv_cq = cq;
			qp_attr.cap.max_send_wr = 1;
			qp_attr.cap.max_recv_wr = 1;
			qp_attr.cap.max_send_sge = 1;
			qp_attr.cap.max_recv_sge = 1;
			qp_attr.cap.max_inline_data = 460;
			qp_attr.qp_type = type_tab[t].type;

			printf("  %s: inline %d ", type_tab[t].name, qp_attr.cap.max_inline_data);

			if (ibv_create_qp(pd, &qp_attr))
				printf("ok (got %d)\n",
				       qp_attr.cap.max_inline_data);
			else
				printf("FAILED\n");
		}
	}

	return 0;
}