On 7/6/2015 5:35 PM, Steve Wise wrote:
-----Original Message-----
From: Sagi Grimberg [mailto:sa...@dev.mellanox.co.il]
Sent: Monday, July 06, 2015 2:51 AM
To: Steve Wise; dledf...@redhat.com
Cc: infinip...@intel.com; sa...@mellanox.com; ogerl...@mellanox.com;
r...@mellanox.com; linux-rdma@vger.kernel.org;
e...@mellanox.com; target-de...@vger.kernel.org
Subject: Re: [PATCH V5 3/5] RDMA/iser: Limit sg tablesize and max_sectors to
device fastreg max depth
On 7/5/2015 8:44 PM, Steve Wise wrote:
Currently the sg tablesize, which dictates fast register page list
depth to use, does not take into account the limits of the rdma device.
So adjust it once we discover the device fastreg max depth limit. Also
adjust the max_sectors based on the resulting sg tablesize.
Signed-off-by: Steve Wise <sw...@opengridcomputing.com>
---
drivers/infiniband/ulp/iser/iscsi_iser.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c
b/drivers/infiniband/ulp/iser/iscsi_iser.c
index 6a594aa..de8730d 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -640,6 +640,15 @@ iscsi_iser_session_create(struct iscsi_endpoint *ep,
SHOST_DIX_GUARD_CRC);
}
+ /*
+ * Limit the sg_tablesize and max_sectors based on the device
+ * max fastreg page list length.
+ */
+ shost->sg_tablesize = min_t(unsigned short, shost->sg_tablesize,
+ ib_conn->device->dev_attr.max_fast_reg_page_list_len);
+ shost->max_sectors = min_t(unsigned int,
+ 1024, (shost->sg_tablesize * PAGE_SIZE) >> 9);
+
The min statement is meaningless for max_sectors - you do a min between
default sg_tablesize and frpl length - so the maximum sg_tablesize is
128 which is 1024 max_sectors.
I'm not following. What if
ib_conn->device->dev_attr.max_fast_reg_page_list_len is say, 32?
Then shost->sg_tablesize is set to 32, and max_sectors is set to (32*4K) >> 9
== 256 512B sectors.
Correct - but it cannot exceed 1024 (as it is derived from sg_tablesize
which is maximum 128).
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