Re: [PATCH net-next v5 1/2] net/smc: make wr buffer count configurable
From: Bagas Sanjaya <hidden>
Date: 2025-10-01 10:30:04
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linux-doc, linux-rdma, linux-s390, lkml
On Mon, Sep 29, 2025 at 02:00:00AM +0200, Halil Pasic wrote:
quoted hunk ↗ jump to hunk
diff --git a/Documentation/networking/smc-sysctl.rst b/Documentation/networking/smc-sysctl.rst index a874d007f2db..5de4893ef3e7 100644 --- a/Documentation/networking/smc-sysctl.rst +++ b/Documentation/networking/smc-sysctl.rst@@ -71,3 +71,39 @@ smcr_max_conns_per_lgr - INTEGER acceptable value ranges from 16 to 255. Only for SMC-R v2.1 and later. Default: 255 + +smcr_max_send_wr - INTEGER + So called work request buffers are SMCR link (and RDMA queue pair) level
So-called
+ resources necessary for performing RDMA operations. Since up to 255 + connections can share a link group and thus also a link and the number + of the work request buffers is decided when the link is allocated, + depending on the workload it can be a bottleneck in a sense that threads + have to wait for work request buffers to become available. Before the + introduction of this control the maximal number of work request buffers + available on the send path used to be hard coded to 16. With this control + it becomes configurable. The acceptable range is between 2 and 2048. + + Please be aware that all the buffers need to be allocated as a physically + continuous array in which each element is a single buffer and has the size + of SMC_WR_BUF_SIZE (48) bytes. If the allocation fails we give up much + like before having this control. + + Default: 16 + +smcr_max_recv_wr - INTEGER + So called work request buffers are SMCR link (and RDMA queue pair) level
Ditto.
+ resources necessary for performing RDMA operations. Since up to 255 + connections can share a link group and thus also a link and the number + of the work request buffers is decided when the link is allocated, + depending on the workload it can be a bottleneck in a sense that threads + have to wait for work request buffers to become available. Before the + introduction of this control the maximal number of work request buffers + available on the receive path used to be hard coded to 16. With this control + it becomes configurable. The acceptable range is between 2 and 2048. + + Please be aware that all the buffers need to be allocated as a physically + continuous array in which each element is a single buffer and has the size + of SMC_WR_BUF_SIZE (48) bytes. If the allocation fails we give up much + like before having this control. + + Default: 48
Thanks. -- An old man doll... just what I always wanted! - Clara
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