Re: [pull request][for-next 0/9] Generic DIM lib for netdev and RDMA

[Max Gurtovoy]

On 6/6/2019 10:14 AM, Leon Romanovsky wrote:
On Wed, Jun 05, 2019 at 11:24:31PM +0000, Saeed Mahameed wrote:
Hi Dave, Doug & Jason

This series improves DIM - Dynamically-tuned Interrupt
Moderation- to be generic for netdev and RDMA use-cases.

 From Tal and Yamin:
The first 7 patches provide the necessary refactoring to current net_dim
library which affect some net drivers who are using the API.

The last 2 patches provide the RDMA implementation for DIM.

For more information please see tag log below.

Once we are all happy with the series, please pull to net-next and
rdma-next trees.

Thanks,
Saeed.

---
The following changes since commit cd6c84d8f0cdc911df435bb075ba22ce3c605b07:

   Linux 5.2-rc2 (2019-05-26 16:49:19 -0700)

are available in the Git repository at:

   git://git.kernel.org/pub/scm/linux/kernel/git/saeed/linux.git 
tags/dim-updates-2019-06-05

for you to fetch changes up to 1ec9974e75e7a58bff1ab17c4fcda17b180ed3bb:

   RDMA/core: Provide RDMA DIM support for ULPs (2019-06-05 16:09:02 -0700)

----------------------------------------------------------------
dim-updates-2019-06-05

From: Tal Gilboa

Implement net DIM over a generic DIM library

net_dim.h lib exposes an implementation of the DIM algorithm for
dynamically-tuned interrupt moderation for networking interfaces.

We want a similar functionality for other protocols, which might need to
optimize interrupts differently. Main motivation here is DIM for NVMf
storage protocol.

Current DIM implementation prioritizes reducing interrupt overhead over
latency. Also, in order to reduce DIM's own overhead, the algorithm might
take some time to identify it needs to change profiles. While this is
acceptable for networking, it might not work well on other scenarios.

Here I propose a new structure to DIM. The idea is to allow a slightly
modified functionality without the risk of breaking Net DIM behavior for
netdev. I verified there are no degradations in current DIM behavior with
the modified solution.

Solution:
- Common logic is declared in include/linux/dim.h and implemented in
   lib/dim/dim.c
- Net DIM (existing) logic is declared in include/linux/net_dim.h and
   implemented in lib/dim/net_dim.c, which uses the common logic from dim.h
- Any new DIM logic will be declared in "/include/linux/new_dim.h" and
    implemented in "lib/dim/new_dim.c".
- This new implementation will expose modified versions of profiles,
   dim_step() and dim_decision().

Pros for this solution are:
- Zero impact on existing net_dim implementation and usage
- Relatively more code reuse (compared to two separate solutions)
- Increased extensibility

----------------------------------------------------------------
Tal Gilboa (6):
       linux/dim: Move logic to dim.h
       linux/dim: Remove "net" prefix from internal DIM members
       linux/dim: Rename externally exposed macros
       linux/dim: Rename net_dim_sample() to net_dim_update_sample()
       linux/dim: Rename externally used net_dim members
       linux/dim: Move implementation to .c files

Yamin Friedman (3):
       linux/dim: Add completions count to dim_sample
       linux/dim: Implement rdma_dim
       RDMA/core: Provide RDMA DIM support for ULPs
Saeed,

No, for the RDMA patches.
We need to see usage of those APIs before merging.

I've asked Yamin to prepare patches for NVMeoF initiator and target for 
review, so I guess he has it on his plate (this is how he tested it..).

It might cause conflict with NVMe/blk branch maintained by Sagi, 
Christoph and Jens.

So we need a plan here.



Thanks