[dpdk-dev] [PATCH 23/28] net/ixgbe: use eal I/O device memory read/write API

[Jianbo Liu]

Hi Santosh,

On 22 December 2016 at 20:36, Santosh Shukla
<santosh.shukla at caviumnetworks.com> wrote:
> Hi Jiangbo,
>
> On Thu, Dec 15, 2016 at 08:40:19PM -0800, Santosh Shukla wrote:
>> On Thu, Dec 15, 2016 at 04:37:12PM +0800, Jianbo Liu wrote:
>> > On 14 December 2016 at 09:55, Jerin Jacob
>> > <jerin.jacob at caviumnetworks.com> wrote:
>> > > From: Santosh Shukla <santosh.shukla at caviumnetworks.com>
>> > >
>> >
>> > memory barrier operation is put inside IXGBE_PCI_REG_READ/WRITE in
>> > your change, but I found rte_*mb is called before these macros in some
>> > places.
>> > Can you remove all these redundant calls? And please do the same
>> > checking for other drivers.
>> >
>>
>> Ok.
>>
>> Thinking of adding _relaxed_rd/wr style macro agnostic to arch for ixgbe case
>> in particular. Such that for those code incident:
>> x86 case> first default barrier + relaxed call.
>> arm case> first default barrier + relaxed call.
>>
>> Does that make sense to you? If so then will take care in v2.
>>
>> Santosh.
>
> We spend time looking at drivers code where double barrier
> may happen. Most of them are in driver init path,
> configuration/control path code. So keeping double
> barrier won't impact performance.
>
> We plan to replace only fast path code with _relaxed
> style API's. That way we won't impact each driver
> performance and we'll have the clean port.
>
> Does it make sense? Thought?
>

Yes, please continue your work.