Re: [PATCH v1 7/7] sunrpc: Allow keepalive ping on a credit-full transport

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On 01/30/2017 03:32 PM, Chuck Lever wrote:
> 
>> On Jan 30, 2017, at 3:29 PM, Anna Schumaker <schumaker.anna@xxxxxxxxx> wrote:
>>
>> Hi Chuck,
>>
>> On 01/26/2017 12:56 PM, Chuck Lever wrote:
>>> Allow RPC-over-RDMA to send NULL pings even when the transport has
>>> hit its credit limit.
>>>
>>> One credit is reserved. It may be used only to send a keepalive
>>> ping.
>>>
>>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>>> ---
>>> include/linux/sunrpc/sched.h    |    2 ++
>>> net/sunrpc/xprt.c               |    4 ++++
>>> net/sunrpc/xprtrdma/transport.c |    4 +++-
>>> net/sunrpc/xprtrdma/verbs.c     |   13 ++++++++-----
>>> 4 files changed, 17 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
>>> index 7ba040c..a65278e 100644
>>> --- a/include/linux/sunrpc/sched.h
>>> +++ b/include/linux/sunrpc/sched.h
>>> @@ -127,6 +127,7 @@ struct rpc_task_setup {
>>> #define RPC_TASK_TIMEOUT	0x1000		/* fail with ETIMEDOUT on timeout */
>>> #define RPC_TASK_NOCONNECT	0x2000		/* return ENOTCONN if not connected */
>>> #define RPC_TASK_NO_RETRANS_TIMEOUT	0x4000		/* wait forever for a reply */
>>> +#define RPC_TASK_PRIORITY	0x8000		/* skip congestion control */
>>
>> This file also defines various RPC_PRIORITY_<whatever> values that get used for the task->tk_priority field.  I wonder if there is a better name for this flag that would help keep people from confusing the two later down the line, but I'm also struggling to come up with anything better.
> 
> PRIORITY was a (lead) trial balloon, and also a sign of weak imagination.
> 
> The point of the flag is to bypass congestion control. RPC_TASK_SKIPCONG ?

Something like that could work, yeah.

Anna

> Meh.
> 
> 
>> Thoughts?
>> Anna
>>
>>>
>>> #define RPC_IS_ASYNC(t)		((t)->tk_flags & RPC_TASK_ASYNC)
>>> #define RPC_IS_SWAPPER(t)	((t)->tk_flags & RPC_TASK_SWAPPER)
>>> @@ -135,6 +136,7 @@ struct rpc_task_setup {
>>> #define RPC_IS_SOFT(t)		((t)->tk_flags & (RPC_TASK_SOFT|RPC_TASK_TIMEOUT))
>>> #define RPC_IS_SOFTCONN(t)	((t)->tk_flags & RPC_TASK_SOFTCONN)
>>> #define RPC_WAS_SENT(t)		((t)->tk_flags & RPC_TASK_SENT)
>>> +#define RPC_HAS_PRIORITY(t)	((t)->tk_flags & RPC_TASK_PRIORITY)
>>>
>>> #define RPC_TASK_RUNNING	0
>>> #define RPC_TASK_QUEUED		1
>>> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
>>> index b530a28..e8b7b9f 100644
>>> --- a/net/sunrpc/xprt.c
>>> +++ b/net/sunrpc/xprt.c
>>> @@ -392,6 +392,10 @@ static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *ta
>>> {
>>> 	struct rpc_rqst *req = task->tk_rqstp;
>>>
>>> +	if (RPC_HAS_PRIORITY(task)) {
>>> +		req->rq_cong = 0;
>>> +		return 1;
>>> +	}
>>> 	if (req->rq_cong)
>>> 		return 1;
>>> 	dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n",
>>> diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
>>> index f97c851..e43cc85 100644
>>> --- a/net/sunrpc/xprtrdma/transport.c
>>> +++ b/net/sunrpc/xprtrdma/transport.c
>>> @@ -538,7 +538,9 @@ static void rpcrdma_keepalive_release(void *calldata)
>>>
>>> 	data = xprt_get(xprt);
>>> 	null_task = rpc_call_null_helper(task->tk_client, xprt, NULL,
>>> -					 RPC_TASK_SOFT | RPC_TASK_ASYNC,
>>> +					 RPC_TASK_SOFT |
>>> +					 RPC_TASK_ASYNC |
>>> +					 RPC_TASK_PRIORITY,
>>> 					 &rpcrdma_keepalive_call_ops, data);
>>> 	if (!IS_ERR(null_task))
>>> 		rpc_put_task(null_task);
>>> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
>>> index 7e14b73..3e218dd 100644
>>> --- a/net/sunrpc/xprtrdma/verbs.c
>>> +++ b/net/sunrpc/xprtrdma/verbs.c
>>> @@ -136,19 +136,20 @@
>>> static void
>>> rpcrdma_update_granted_credits(struct rpcrdma_rep *rep)
>>> {
>>> -	struct rpcrdma_msg *rmsgp = rdmab_to_msg(rep->rr_rdmabuf);
>>> 	struct rpcrdma_buffer *buffer = &rep->rr_rxprt->rx_buf;
>>> +	__be32 *p = rep->rr_rdmabuf->rg_base;
>>> 	u32 credits;
>>>
>>> 	if (rep->rr_len < RPCRDMA_HDRLEN_ERR)
>>> 		return;
>>>
>>> -	credits = be32_to_cpu(rmsgp->rm_credit);
>>> +	credits = be32_to_cpup(p + 2);
>>> +	if (credits > buffer->rb_max_requests)
>>> +		credits = buffer->rb_max_requests;
>>> +	/* Reserve one credit for keepalive ping */
>>> +	credits--;
>>> 	if (credits == 0)
>>> 		credits = 1;	/* don't deadlock */
>>> -	else if (credits > buffer->rb_max_requests)
>>> -		credits = buffer->rb_max_requests;
>>> -
>>> 	atomic_set(&buffer->rb_credits, credits);
>>> }
>>>
>>> @@ -914,6 +915,8 @@ struct rpcrdma_rep *
>>> 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
>>> 	int i, rc;
>>>
>>> +	if (r_xprt->rx_data.max_requests < 2)
>>> +		return -EINVAL;
>>> 	buf->rb_max_requests = r_xprt->rx_data.max_requests;
>>> 	buf->rb_bc_srv_max_requests = 0;
>>> 	atomic_set(&buf->rb_credits, 1);
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> --
> Chuck Lever
> 
> 
> 
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Photo]     [Yosemite News]     [Yosemite Photos]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux