SMCR_RMBE_SIZES is the upper boundary of SMC-R's snd_buf and rcv_buf. The maximum bytes of snd_buf and rcv_buf can be calculated by 2^SMCR_ RMBE_SIZES * 16KB. SMCR_RMBE_SIZES = 5 means the upper boundary is 512KB. TCP's snd_buf and rcv_buf max size is configured by net.ipv4.tcp_w/rmem[2] whose defalut value is 4MB or 6MB, is much larger than SMC-R's upper boundary. In some scenarios, such as Recommendation System, the communication pattern is mainly large size send/recv, where the size of snd_buf and rcv_buf greatly affects performance. Due to the upper boundary disadvantage, SMC-R performs poor than TCP in those scenarios. So it is time to enlarge the upper boundary size of SMC-R's snd_buf and rcv_buf, so that the SMC-R's snd_buf and rcv_buf can be configured to larger size for performance gain in such scenarios. The SMC-R rcv_buf's size will be transferred to peer by the field rmbe_size in clc accept and confirm message. The length of the field rmbe_size is four bits, which means the maximum value of SMCR_RMBE_SIZES is 15. In case of frequently adjusting the value of SMCR_RMBE_SIZES in different scenarios, set the value of SMCR_RMBE_SIZES to the maximum value 15, which means the upper boundary of SMC-R's snd_buf and rcv_buf is 512MB. As the real memory usage is determined by the value of net.smc.w/rmem, not by the upper boundary, set the value of SMCR_RMBE_SIZES to the maximum value has no side affects. Signed-off-by: Guangguan Wang <guangguan.wang@xxxxxxxxxxxxxxxxx> Co-developed-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx> Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx> --- net/smc/smc_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index acca3b1a068f..3b95828d9976 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -2006,7 +2006,7 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini) } #define SMCD_DMBE_SIZES 6 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */ -#define SMCR_RMBE_SIZES 5 /* 0 -> 16KB, 1 -> 32KB, .. 5 -> 512KB */ +#define SMCR_RMBE_SIZES 15 /* 0 -> 16KB, 1 -> 32KB, .. 15 -> 512MB */ /* convert the RMB size into the compressed notation (minimum 16K, see * SMCD/R_DMBE_SIZES. -- 2.24.3 (Apple Git-128)
