On 10/26/2014 4:08 PM, Eli Cohen wrote:
On Sun, Oct 26, 2014 at 01:57:33PM +0100, Bart Van Assche wrote:
Applications really need a way to query what the maximum supported
number of scatter/gather entries per work request is. The current
approach, namely using "dev_attr.max_sge - <magic value>" is
cumbersome since this approach doesn't work if the value of max_sge
reported by the HCA is small. I see two possible solutions: either
modify the max_sge value reported by the mlx4 and mlx5 drivers or
introduce a new parameter in struct ib_device_attr.
we already have reported max_sge value. Maybe what we need is another
field, "guarnateed_num_sge" so applicatios providing this value can be
sure it would succeed (or there is some other problem). Then they can
either use this value or iterate from max_sge down to
guarnateed_num_sge to find the highest possible value.
Eli, can we be a bit more restrictive and report something which would
work?
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