kernel/linux.git/include/rdma/rw.h, branch v6.6.132

RDMA/core: add rdma_rw_max_sge() helper for SQ sizing

2026-03-04T12:20:02+00:00

[ Upstream commit afcae7d7b8a278a6c29e064f99e5bafd4ac1fb37 ] svc_rdma_accept() computes sc_sq_depth as the sum of rq_depth and the number of rdma_rw contexts (ctxts). This value is used to allocate the Send CQ and to initialize the sc_sq_avail credit pool. However, when the device uses memory registration for RDMA operations, rdma_rw_init_qp() inflates the QP's max_send_wr by a factor of three per context to account for REG and INV work requests. The Send CQ and credit pool remain sized for only one work request per context, causing Send Queue exhaustion under heavy NFS WRITE workloads. Introduce rdma_rw_max_sge() to compute the actual number of Send Queue entries required for a given number of rdma_rw contexts. Upper layer protocols call this helper before creating a Queue Pair so that their Send CQs and credit accounting match the QP's true capacity. Update svc_rdma_accept() to use rdma_rw_max_sge() when computing sc_sq_depth, ensuring the credit pool reflects the work requests that rdma_rw_init_qp() will reserve. Reviewed-by: Christoph Hellwig Fixes: 00bd1439f464 ("RDMA/rw: Support threshold for registration vs scattering to local pages") Signed-off-by: Chuck Lever Link: https://patch.msgid.link/20260128005400.25147-5-cel@kernel.org Signed-off-by: Leon Romanovsky Signed-off-by: Sasha Levin

RDMA: Support more than 255 rdma ports

2021-03-26T12:31:21+00:00

Current code uses many different types when dealing with a port of a RDMA device: u8, unsigned int and u32. Switch to u32 to clean up the logic. This allows us to make (at least) the core view consistent and use the same type. Unfortunately not all places can be converted. Many uverbs functions expect port to be u8 so keep those places in order not to break UAPIs. HW/Spec defined values must also not be changed. With the switch to u32 we now can support devices with more than 255 ports. U32_MAX is reserved to make control logic a bit easier to deal with. As a device with U32_MAX ports probably isn't going to happen any time soon this seems like a non issue. When a device with more than 255 ports is created uverbs will report the RDMA device as having 255 ports as this is the max currently supported. The verbs interface is not changed yet because the IBTA spec limits the port size in too many places to be u8 and all applications that relies in verbs won't be able to cope with this change. At this stage, we are extending the interfaces that are using vendor channel solely Once the limitation is lifted mlx5 in switchdev mode will be able to have thousands of SFs created by the device. As the only instance of an RDMA device that reports more than 255 ports will be a representor device and it exposes itself as a RAW Ethernet only device CM/MAD/IPoIB and other ULPs aren't effected by this change and their sysfs/interfaces that are exposes to userspace can remain unchanged. While here cleanup some alignment issues and remove unneeded sanity checks (mainly in rdmavt), Link: https://lore.kernel.org/r/20210301070420.439400-1-leon@kernel.org Signed-off-by: Mark Bloch Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe

Merge tag 'v5.2-rc6' into rdma.git for-next

2019-06-29T00:18:23+00:00

For dependencies in next patches. Resolve conflicts: - Use uverbs_get_cleared_udata() with new cq allocation flow - Continue to delete nes despite SPDX conflict - Resolve list appends in mlx5_command_str() - Use u16 for vport_rule stuff - Resolve list appends in struct ib_client Signed-off-by: Jason Gunthorpe

RDMA/rw: Use IB_WR_REG_MR_INTEGRITY for PI handover

2019-06-24T14:49:28+00:00

Replace the old signature handover API with the new one. The new API simplifes PI handover code complexity for ULPs and improve performance. For RW API it will reduce the maximum number of work requests per task and the need of dealing with multiple MRs (and their registrations and invalidations) per task. All the mappings and registration of the data and the protection buffers is done by the LLD using a single WR and a special MR type (IB_MR_TYPE_INTEGRITY) for the PI handover operation. The setup of the tested benchmark (using iSER ULP): - 2 servers with 24 cores (1 initiator and 1 target) - ConnectX-4/ConnectX-5 adapters - 24 target sessions with 1 LUN each - ramdisk backstore - PI active Performance results running fio (24 jobs, 128 iodepth) using write_generate=1 and read_verify=1 (w/w.o patch): bs IOPS(read) IOPS(write) ---- ---------- ---------- 512 1243.3K/1182.3K 1725.1K/1680.2K 4k 571233/528835 743293/748259 32k 72388/71086 71789/93573 Using write_generate=0 and read_verify=0 (w/w.o patch): bs IOPS(read) IOPS(write) ---- ---------- ---------- 512 1572.1K/1427.2K 1823.5K/1724.3K 4k 921992/916194 753772/768267 32k 75052/73960 73180/95484 There is a performance degradation when writing big block sizes. Degradation is caused by the complexity of combining multiple indirections and perform RDMA READ operation from it. This will be fixed in the following patches by reducing the indirections if possible. Signed-off-by: Israel Rukshin Reviewed-by: Max Gurtovoy Reviewed-by: Christoph Hellwig Signed-off-by: Jason Gunthorpe

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288

2019-06-05T15:36:37+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms and conditions of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 263 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Alexios Zavras Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141901.208660670@linutronix.de Signed-off-by: Greg Kroah-Hartman

rdma core: Add rdma_rw_mr_payload()

2017-09-05T19:15:30+00:00

The amount of payload per MR depends on device capabilities and the memory registration mode in use. The new rdma_rw API hides both, making it difficult for ULPs to determine how large their transport send queues need to be. Expose the MR payload information via a new API. Signed-off-by: Chuck Lever Acked-by: Doug Ledford Signed-off-by: J. Bruce Fields

IB/core: add RW API support for signature MRs

2016-05-13T17:37:20+00:00

Signed-off-by: Christoph Hellwig Signed-off-by: Doug Ledford

IB/core: generic RDMA READ/WRITE API

2016-05-13T17:37:19+00:00

This supports both manual mapping of lots of SGEs, as well as using MRs from the QP's MR pool, for iWarp or other cases where it's more optimal. For now, MRs are only used for iWARP transports. The user of the RDMA-RW API must allocate the QP MR pool as well as size the SQ accordingly. Thanks to Steve Wise for testing, fixing and rewriting the iWarp support, and to Sagi Grimberg for ideas, reviews and fixes. Signed-off-by: Christoph Hellwig Signed-off-by: Doug Ledford