korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-12-18 00:24:58 +08:00
Code Issues Packages Projects Releases Wiki Activity

RDMA/cma: Change RoCE packet life time from 18 to 16

Browse Source 
The ack timeout retransmission time is affected by the following two
factors: one is packet life time, another is the HCA processing time.

Now the default packet lifetime(CMA_IBOE_PACKET_LIFETIME) is 18.

That means the minimum ack timeout is 2
seconds (2^(18+1)*4us=2.097seconds).  The packet lifetime means the
maximum transmission time of packets on the network, 2 seconds is too
long.

Assume the network is a clos topology with three layers, every packet will
pass through five hops of switches. Assume the buffer of every switch is
128MB and the port transmission rate is 25 Gbit/s, the maximum
transmission time of the packet is 200ms(128MB*5/25Gbit/s).  Add double
redundancy, it is less than 500ms.

So change the CMA_IBOE_PACKET_LIFETIME to 16, the maximum transmission
time of the packet will be about 500+ms, it is long enough.

Link: https://lore.kernel.org/r/20221125010026.755-1-lengchao@huawei.com
Signed-off-by: Chao Leng <lengchao@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Chao Leng 2022-11-25 09:00:26 +08:00 committed by Jason Gunthorpe
parent d074f0aebd
commit fb4907f487
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/infiniband/core/cma.c
View File

@ -47,7 +47,7 @@ MODULE_LICENSE("Dual BSD/GPL");
#define CMA_CM_RESPONSE_TIMEOUT 20
#define CMA_MAX_CM_RETRIES 15
#define CMA_CM_MRA_SETTING (IB_CM_MRA_FLAG_DELAY | 24)
#define CMA_IBOE_PACKET_LIFETIME 18
#define CMA_IBOE_PACKET_LIFETIME 16
#define CMA_PREFERRED_ROCE_GID_TYPE IB_GID_TYPE_ROCE_UDP_ENCAP
static const char * const cma_events[] = {