On 9/17/15 5:42 AM, Sagi Grimberg wrote:
Hi all,
As discussed on the linux-rdma list, there is plenty of room for
improvement in our memory registration APIs. We keep finding
ULPs that are duplicating code, sometimes use wrong strategies
and mis-use our current API.
As a first step, this patch set replaces the fast registration API
to accept a kernel common struct scatterlist and takes care of
the page vector construction in the core layer with hooks for the
drivers HW specific assignments. This allows to remove a common
code duplication as it was done in each and every ULP driver.
The changes from v0 (WIP) are:
- Rebased on top of 4.3-rc1 + Christoph's ib_send_wr conversion patches
- Allow the ULP to pass page_size argument to ib_map_mr_sg in order
to have it work better in some specific workloads. This suggestion
came from Bart Van Assache which pointed out that some applications
might use page sizes significantly smaller than the system PAGE_SIZE
of specific architectures
- Fixed some logical bugs in ib_sg_to_pages
- Added a set_page function pointer for drivers to pass to ib_sg_to_pages
so some drivers (e.g mlx4, mlx5, nes) can avoid keeping a second page
vector and/or re-iterate on the page vector in order to perform HW specific
assignments (big/little endian conversion, extra flags)
- Converted SRP initiator and RDS iwarp ULPs to the new API
- Removed fast registration code from hfi1 driver (as it isn't supported
anyway). I assume that the correct place to get the support back would
be in a shared SW library (hfi1, qib, rxe).
- Updated the change logs
So far my tests covered:
- ULPs:
* iser initiator
* iser target
* xprtrdma
* svcrdma
- Drivers:
* mlx4
* mlx5
* Steve Wise was kind enough to run NFS client/server over cxgb4 and I
have yet to receive any negative feedback from him.
I don't have access to other HW devices (qib, nes) nor iwarp devices so RDS is
compile tested only.
Nice to see this consolidaton happening. I too don't have access to
iWARP hardware for RDS test but will use this series and convert our WIP
IB fastreg code and see how it goes.
Regards,
Santosh
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