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| author | Chao Leng <lengchao@huawei.com> | 2022-11-25 09:00:26 +0800 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@nvidia.com> | 2022-12-07 19:44:27 -0400 |
| commit | fb4907f487254375830f135dcfe5dd7e6f8b705f (patch) | |
| tree | 7b8fb432df1bf392434bc92bf1a420102d3c32a6 /drivers/infiniband/core/cma.c | |
| parent | d074f0aebde5649f7a9f1807551efc019b8e81c4 (diff) | |
| download | linux-fb4907f487254375830f135dcfe5dd7e6f8b705f.tar.bz2 | |
RDMA/cma: Change RoCE packet life time from 18 to 16
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>
Diffstat (limited to 'drivers/infiniband/core/cma.c')
| -rw-r--r-- | drivers/infiniband/core/cma.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index cc2222b85c88..2f5b5e6f3d11 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -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[] = { |