> On Mar 7, 2018, at 3:00 PM, Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> wrote:
>
>
>
> On 03/06/2018 05:30 PM, Chuck Lever wrote:
>>
>>
>>> On Mar 6, 2018, at 5:07 PM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
>>>
>>>
>>>
>>>> On Mar 6, 2018, at 5:02 PM, Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> wrote:
>>>>
>>>> Hi Chuck,
>>>>
>>>> I'm seeing a huge performance hit with this patch. I'm just running cthon over TCP, and it goes from finishing in 22 seconds to taking well over 5 minutes. I seem to only see this on the read and write tests, such as basic test5 taking a minute to finish:
>>>>
>>>> ./test5: read and write
>>>> wrote 1048576 byte file 10 times in 60.35 seconds (173737 bytes/sec)
>>>> read 1048576 byte file 10 times in 0.0 seconds (-2147483648 bytes/sec)
>>>> ./test5 ok.
>>>
>>> OK. This looks like write is impacted, but this test doesn't
>>> actually perform any reads on the wire. Try iozone with -I,
>>> maybe? That would show results for both read and write.
>>
>> Hum.
>>
>> Stock v4.16-rc4:
>>
>> ./test5: read and write
>> wrote 1048576 byte file 10 times in 0.2 seconds (350811642 bytes/sec)
>> read 1048576 byte file 10 times in 0.0 seconds (-2147483648 bytes/sec)
>> ./test5 ok.
>>
>>
>> v4.16-rc4 with my full set of patches:
>>
>> ./test5: read and write
>> wrote 1048576 byte file 10 times in 0.2 seconds (354236681 bytes/sec)
>> read 1048576 byte file 10 times in 0.0 seconds (-2147483648 bytes/sec)
>> ./test5 ok.
>>
>> I don't see a regression here. Let me know how it goes!
>
> I'm using rc4 too, so maybe it's something different in my setup?
What is your setup, exactly? I assume your client is maybe a
single CPU guest, and the server is the same, and both are
hosted on one system?
> Making this change fixes the issue for me:
>
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index a394b4635f8e..273847f7e455 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -987,8 +987,6 @@ bool xprt_prepare_transmit(struct rpc_task *task)
> task->tk_status = -EAGAIN;
> goto out_unlock;
> }
> - if (likely(!bc_prealloc(req)))
> - req->rq_xid = xprt_alloc_xid(xprt);
> ret = true;
> out_unlock:
> spin_unlock_bh(&xprt->transport_lock);
> @@ -1315,6 +1313,7 @@ void xprt_request_init(struct rpc_task *task)
> req->rq_task = task;
> req->rq_xprt = xprt;
> req->rq_buffer = NULL;
> + req->rq_xid = xprt_alloc_xid(xprt);
xprt_alloc_xid is just
1299 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
1300 {
1301 return (__force __be32)xprt->xid++;
1302 }
I don't believe the new call site for xprt_request_init is
adequately serialized for this to be safe in general. That's why
I'm calling xprt_alloc_xid in xprt_prepare_transmit, behind the
transport_lock.
However, I think we need to explain why that helps your performance
issue, because it doesn't make sense to me that this would make a
difference. Why did you think to try this change? Is there evidence
on the wire of XID re-use, for example?
> req->rq_connect_cookie = xprt->connect_cookie - 1;
> req->rq_bytes_sent = 0;
> req->rq_snd_buf.len = 0;
>
>
> Anna
>
>>
>>
>>>> I haven't dug into this too deeply, but my best guess is that maybe it's due to adding a call to xprt_request_init() in net/sunrpc/clnt.c:call_reserveresult()
>>>
>>> It wasn't added there, it was moved from xprt_alloc_slot. So,
>>> it's not new work per-RPC.
>>>
>>> Any additional information would be appreciated!
>>>
>>>
>>>> Thoughts?
>>>> Anna
>>>>
>>>> On 03/05/2018 03:13 PM, Chuck Lever wrote:
>>>>> alloc_slot is a transport-specific op, but initializing an rpc_rqst
>>>>> is common to all transports. Move initialization to common code in
>>>>> preparation for adding a transport-specific alloc_slot to xprtrdma.
>>>>>
>>>>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>>>>> ---
>>>>> include/linux/sunrpc/xprt.h | 1 +
>>>>> net/sunrpc/clnt.c | 1 +
>>>>> net/sunrpc/xprt.c | 12 +++++++-----
>>>>> 3 files changed, 9 insertions(+), 5 deletions(-)
>>>>>
>>>>> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
>>>>> index 5fea0fb..9784e28 100644
>>>>> --- a/include/linux/sunrpc/xprt.h
>>>>> +++ b/include/linux/sunrpc/xprt.h
>>>>> @@ -324,6 +324,7 @@ struct xprt_class {
>>>>> struct rpc_xprt *xprt_create_transport(struct xprt_create *args);
>>>>> void xprt_connect(struct rpc_task *task);
>>>>> void xprt_reserve(struct rpc_task *task);
>>>>> +void xprt_request_init(struct rpc_task *task);
>>>>> void xprt_retry_reserve(struct rpc_task *task);
>>>>> int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
>>>>> int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
>>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
>>>>> index 6e432ec..226f558 100644
>>>>> --- a/net/sunrpc/clnt.c
>>>>> +++ b/net/sunrpc/clnt.c
>>>>> @@ -1546,6 +1546,7 @@ void rpc_force_rebind(struct rpc_clnt *clnt)
>>>>> task->tk_status = 0;
>>>>> if (status >= 0) {
>>>>> if (task->tk_rqstp) {
>>>>> + xprt_request_init(task);
>>>>> task->tk_action = call_refresh;
>>>>> return;
>>>>> }
>>>>> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
>>>>> index 70f0050..a394b46 100644
>>>>> --- a/net/sunrpc/xprt.c
>>>>> +++ b/net/sunrpc/xprt.c
>>>>> @@ -66,7 +66,7 @@
>>>>> * Local functions
>>>>> */
>>>>> static void xprt_init(struct rpc_xprt *xprt, struct net *net);
>>>>> -static void xprt_request_init(struct rpc_task *, struct rpc_xprt *);
>>>>> +static __be32 xprt_alloc_xid(struct rpc_xprt *xprt);
>>>>> static void xprt_connect_status(struct rpc_task *task);
>>>>> static int __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
>>>>> static void __xprt_put_cong(struct rpc_xprt *, struct rpc_rqst *);
>>>>> @@ -987,6 +987,8 @@ bool xprt_prepare_transmit(struct rpc_task *task)
>>>>> task->tk_status = -EAGAIN;
>>>>> goto out_unlock;
>>>>> }
>>>>> + if (likely(!bc_prealloc(req)))
>>>>> + req->rq_xid = xprt_alloc_xid(xprt);
>>>>> ret = true;
>>>>> out_unlock:
>>>>> spin_unlock_bh(&xprt->transport_lock);
>>>>> @@ -1163,10 +1165,10 @@ void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
>>>>> out_init_req:
>>>>> xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
>>>>> xprt->num_reqs);
>>>>> + spin_unlock(&xprt->reserve_lock);
>>>>> +
>>>>> task->tk_status = 0;
>>>>> task->tk_rqstp = req;
>>>>> - xprt_request_init(task, xprt);
>>>>> - spin_unlock(&xprt->reserve_lock);
>>>>> }
>>>>> EXPORT_SYMBOL_GPL(xprt_alloc_slot);
>>>>>
>>>>> @@ -1303,8 +1305,9 @@ static inline void xprt_init_xid(struct rpc_xprt *xprt)
>>>>> xprt->xid = prandom_u32();
>>>>> }
>>>>>
>>>>> -static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
>>>>> +void xprt_request_init(struct rpc_task *task)
>>>>> {
>>>>> + struct rpc_xprt *xprt = task->tk_xprt;
>>>>> struct rpc_rqst *req = task->tk_rqstp;
>>>>>
>>>>> INIT_LIST_HEAD(&req->rq_list);
>>>>> @@ -1312,7 +1315,6 @@ static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
>>>>> req->rq_task = task;
>>>>> req->rq_xprt = xprt;
>>>>> req->rq_buffer = NULL;
>>>>> - req->rq_xid = xprt_alloc_xid(xprt);
>>>>> req->rq_connect_cookie = xprt->connect_cookie - 1;
>>>>> req->rq_bytes_sent = 0;
>>>>> req->rq_snd_buf.len = 0;
>>>>>
>>>
>>> --
>>> 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
>>
>> --
>> Chuck Lever
--
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
