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Wed, 23 Nov 2022 11:19:22 +0000 (GMT) Received: from [9.171.0.166] (unknown [9.171.0.166]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 23 Nov 2022 11:19:22 +0000 (GMT) Message-ID: <4c5d74f8-c5de-d50c-0682-4435de21660a@linux.ibm.com> Date: Wed, 23 Nov 2022 12:19:19 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH net-next] net/smc: Unbind smc control from tcp control To: Tony Lu Cc: David Miller , Jakub Kicinski , netdev@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens , Alexandra Winter , Wenjia Zhang , Thorsten Winkler , Stefan Raspl , Karsten Graul References: <20221123105830.17167-1-jaka@linux.ibm.com> From: Jan Karcher Organization: IBM - Network Linux on Z In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: viq4UnfIB8E4658vbD_xhB3_bAA3ikh3 X-Proofpoint-GUID: gibViH1E4H9ok7H8rK9bFYU-UoKOp8LE X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-23_06,2022-11-23_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 priorityscore=1501 impostorscore=0 suspectscore=0 clxscore=1015 lowpriorityscore=0 malwarescore=0 phishscore=0 spamscore=0 mlxscore=0 adultscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211230083 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 23/11/2022 12:13, Tony Lu wrote: > On Wed, Nov 23, 2022 at 11:58:30AM +0100, Jan Karcher wrote: >> In the past SMC used the values of tcp_{w|r}mem to create the send >> buffer and RMB. We now have our own sysctl knobs to tune them without >> influencing the TCP default. >> >> This patch removes the dependency on the TCP control by providing our >> own initial values which aim for a low memory footprint. > > +1, before introducing sysctl knobs of SMC, we were going to get rid of > TCP and have SMC own values. Now this does it, So I very much agree with > this. > >> >> Signed-off-by: Jan Karcher >> Reviewed-by: Wenjia Zhang >> --- >> Documentation/networking/smc-sysctl.rst | 4 ++-- >> net/smc/smc_core.h | 6 ++++-- >> net/smc/smc_sysctl.c | 10 ++++++---- >> 3 files changed, 12 insertions(+), 8 deletions(-) >> >> diff --git a/Documentation/networking/smc-sysctl.rst b/Documentation/networking/smc-sysctl.rst >> index 6d8acdbe9be1..a1c634d3690a 100644 >> --- a/Documentation/networking/smc-sysctl.rst >> +++ b/Documentation/networking/smc-sysctl.rst >> @@ -44,7 +44,7 @@ smcr_testlink_time - INTEGER >> >> wmem - INTEGER >> Initial size of send buffer used by SMC sockets. >> - The default value inherits from net.ipv4.tcp_wmem[1]. >> + The default value aims for a small memory footprint and is set to 16KiB. >> >> The minimum value is 16KiB and there is no hard limit for max value, but >> only allowed 512KiB for SMC-R and 1MiB for SMC-D. >> @@ -53,7 +53,7 @@ wmem - INTEGER >> >> rmem - INTEGER >> Initial size of receive buffer (RMB) used by SMC sockets. >> - The default value inherits from net.ipv4.tcp_rmem[1]. >> + The default value aims for a small memory footprint and is set to 64KiB. >> >> The minimum value is 16KiB and there is no hard limit for max value, but >> only allowed 512KiB for SMC-R and 1MiB for SMC-D. >> diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h >> index 285f9bd8e232..67c3937f341d 100644 >> --- a/net/smc/smc_core.h >> +++ b/net/smc/smc_core.h >> @@ -206,8 +206,10 @@ struct smc_rtoken { /* address/key of remote RMB */ >> u32 rkey; >> }; >> >> -#define SMC_BUF_MIN_SIZE 16384 /* minimum size of an RMB */ >> -#define SMC_RMBE_SIZES 16 /* number of distinct RMBE sizes */ >> +#define SMC_SNDBUF_INIT_SIZE 16384 /* initial size of send buffer */ >> +#define SMC_RCVBUF_INIT_SIZE 65536 /* initial size of receive buffer */ >> +#define SMC_BUF_MIN_SIZE 16384 /* minimum size of an RMB */ >> +#define SMC_RMBE_SIZES 16 /* number of distinct RMBE sizes */ >> /* theoretically, the RFC states that largest size would be 512K, >> * i.e. compressed 5 and thus 6 sizes (0..5), despite >> * struct smc_clc_msg_accept_confirm.rmbe_size being a 4 bit value (0..15) >> diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c >> index b6f79fabb9d3..a63aa79d4856 100644 >> --- a/net/smc/smc_sysctl.c >> +++ b/net/smc/smc_sysctl.c >> @@ -19,8 +19,10 @@ >> #include "smc_llc.h" >> #include "smc_sysctl.h" >> >> -static int min_sndbuf = SMC_BUF_MIN_SIZE; >> -static int min_rcvbuf = SMC_BUF_MIN_SIZE; >> +static int initial_sndbuf = SMC_SNDBUF_INIT_SIZE; >> +static int initial_rcvbuf = SMC_RCVBUF_INIT_SIZE; >> +static int min_sndbuf = SMC_BUF_MIN_SIZE; >> +static int min_rcvbuf = SMC_BUF_MIN_SIZE; >> >> static struct ctl_table smc_table[] = { >> { >> @@ -88,8 +90,8 @@ int __net_init smc_sysctl_net_init(struct net *net) >> net->smc.sysctl_autocorking_size = SMC_AUTOCORKING_DEFAULT_SIZE; >> net->smc.sysctl_smcr_buf_type = SMCR_PHYS_CONT_BUFS; >> net->smc.sysctl_smcr_testlink_time = SMC_LLC_TESTLINK_DEFAULT_TIME; >> - WRITE_ONCE(net->smc.sysctl_wmem, READ_ONCE(net->ipv4.sysctl_tcp_wmem[1])); >> - WRITE_ONCE(net->smc.sysctl_rmem, READ_ONCE(net->ipv4.sysctl_tcp_rmem[1])); >> + WRITE_ONCE(net->smc.sysctl_wmem, initial_sndbuf); >> + WRITE_ONCE(net->smc.sysctl_rmem, initial_rcvbuf); > > Maybe we can use SMC_{SND|RCV}BUF_INIT_SIZE macro directly, instead of > new variables. The reason i created the new variables is that min_{snd|rcv}buf also have their own variables. I know it is not needed but thought it was cleaner. If you have a strong opinion on using the value directly i can change it. Please let me know if you want it changed. - Jan > > Cheers, > Tony Lu > >> >> return 0; >> >> -- >> 2.34.1