On Thu, Feb 20, 2025 at 6:05 PM Jacob Moroni <jmoroni@xxxxxxxxxx> wrote:
>
> In workloads where there are many processes establishing
> connections using RDMA CM in parallel (large scale MPI),
> there can be heavy contention for mad_agent_lock in
> cm_alloc_msg.
>
> This contention can occur while inside of a spin_lock_irq
> region, leading to interrupts being disabled for extended
> durations on many cores. Furthermore, it leads to the
> serialization of rdma_create_ah calls, which has negative
> performance impacts for NICs which are capable of processing
> multiple address handle creations in parallel.
>
> The end result is the machine becoming unresponsive, hung
> task warnings, netdev TX timeouts, etc.
>
> Since the lock appears to be only for protection from
> cm_remove_one, it can be changed to a rwlock to resolve
> these issues.
>
> Reproducer:
>
> Server:
> for i in $(seq 1 512); do
> ucmatose -c 32 -p $((i + 5000)) &
> done
>
> Client:
> for i in $(seq 1 512); do
> ucmatose -c 32 -p $((i + 5000)) -s 10.2.0.52 &
> done
>
> Fixes: 76039ac9095f5ee5 ("IB/cm: Protect cm_dev, cm_ports and
> mad_agent with kref and lock")
Fixes: tag should be on a single line.
> Signed-off-by: Jacob Moroni <jmoroni@xxxxxxxxxx>
> ---
It seems your patch is mangled.
Can you use "git send-email" to resend it ?
