| Message ID | 20240603030019.91346-1-guangguan.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | net/smc: Change the upper boundary of SMC-R's snd_buf and rcv_buf to 512MB | expand |
Hello: This series was applied to netdev/net-next.git (main) by David S. Miller <davem@davemloft.net>: On Mon, 3 Jun 2024 11:00:17 +0800 you wrote: > 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 default value is 4MB or 6MB, is much larger than SMC-R's upper > boundary. > > [...] Here is the summary with links: - [net-next,v2,1/2] net/smc: set rmb's SG_MAX_SINGLE_ALLOC limitation only when CONFIG_ARCH_NO_SG_CHAIN is defined https://git.kernel.org/netdev/net-next/c/3ac14b9dfbd3 - [net-next,v2,2/2] net/smc: change SMCR_RMBE_SIZES from 5 to 15 https://git.kernel.org/netdev/net-next/c/2f4b101c542e You are awesome, thank you!
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 default 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. Guangguan Wang (2): net/smc: set rmb's SG_MAX_SINGLE_ALLOC limitation only when CONFIG_ARCH_NO_SG_CHAIN is defined net/smc: change SMCR_RMBE_SIZES from 5 to 15 net/smc/smc_core.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)