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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , "D. Wythe" , Dust Li , Sidraya Jayagond , Wenjia Zhang , Mahanta Jambigi , Tony Lu , Wen Gu , Guangguan Wang , netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH net-next v5 1/2] net/smc: make wr buffer count configurable Message-ID: References: <20250929000001.1752206-1-pasic@linux.ibm.com> <20250929000001.1752206-2-pasic@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="XTnKR8OXozLogMib" Content-Disposition: inline In-Reply-To: <20250929000001.1752206-2-pasic@linux.ibm.com> --XTnKR8OXozLogMib Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Sep 29, 2025 at 02:00:00AM +0200, Halil Pasic wrote: > diff --git a/Documentation/networking/smc-sysctl.rst b/Documentation/netw= orking/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. > =20 > 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 contr= ol > + it becomes configurable. The acceptable range is between 2 and 2048. > + > + Please be aware that all the buffers need to be allocated as a physical= ly > + continuous array in which each element is a single buffer and has the s= ize > + 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 co= ntrol > + it becomes configurable. The acceptable range is between 2 and 2048. > + > + Please be aware that all the buffers need to be allocated as a physical= ly > + continuous array in which each element is a single buffer and has the s= ize > + of SMC_WR_BUF_SIZE (48) bytes. If the allocation fails we give up much > + like before having this control. > + > + Default: 48 Thanks. --=20 An old man doll... just what I always wanted! - Clara --XTnKR8OXozLogMib Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQSSYQ6Cy7oyFNCHrUH2uYlJVVFOowUCaN0CowAKCRD2uYlJVVFO o0wMAQC5im7T2Vp9QlkibFW/54g3imCkfNlm7IUNsqBjTp2m9AEA1GNBLgxsziTy v2vNJmcJSA7s6ugOR+dFS8j67OYO3Qs= =jHsY -----END PGP SIGNATURE----- --XTnKR8OXozLogMib--