Re: [PATCH RFC 1/2] IB/core: Introduce Fast Indirect Memory Registration verbs API

[Sagi Grimberg <sagig-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

On 10/9/2014 11:13 PM, Or Gerlitz wrote:
> On Tue, Oct 7, 2014, Sagi Grimberg <sagig-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> wrote:
> [...]
>>   enum ib_signature_prot_cap {
>> @@ -182,6 +183,7 @@ struct ib_device_attr {
>>          int                     max_srq_wr;
>>          int                     max_srq_sge;
>>          unsigned int            max_fast_reg_page_list_len;
>> +       unsigned int            max_indir_reg_mr_list_len;
>
> The indirection registration list is basically made of  struct ib_sge
> objects which are posted on a send-like work-request, any reason  to
> have a dedicated dev cap attribute for that and not use the already
> existing one (max_sge)?
>

Hi Or,

max_send_sge capability is how many ib_sge's the device can handle in a
single send work request which takes into consideration element such as
wqe control segment size and sq reservations. This is different from how
many ib_sge's the device can register to a single indirect memory key
which is free of such limitations.

So given these are different capabilities I prefer to expose them in
different attributes.

Sagi.
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