Bugfix: SQ overflow

docs/cn/rdma.md

@@ -35,7 +35,7 @@ RDMA与TCP不同，不使用socket接口进行通信。但是在实现上仍然
 
 brpc内部使用RDMA RC模式，每个RdmaEndpoint对应一个QP。RDMA连接建立依赖于前置TCP建连，TCP建连后双方交换必要参数，如GID、QPN等，再发起RDMA连接并实现数据传输。这个过程我们称为握手（参见RdmaEndpoint）。因为握手需要TCP连接，因此RdmaEndpoint所在的Socket类中，原本的TCP fd仍然有效。握手过程采用了brpc中已有的AppConnect逻辑。注意，握手用的TCP连接在后续数据传输阶段并不会收发数据，但仍保持为EST状态。一旦TCP连接中断，其上对应的RDMA连接同样会置错。
 
-RdmaEndpoint数据传输逻辑的第一个重要特性是零拷贝。要发送的所有数据默认都存放在IOBuf的Block中，因此所发送的Block需要等到对端确认接收完成后才可以释放，这些Block的引用被存放于RdmaEndpoint::_sbuf中。而要实现接收零拷贝，则需要确保接受端所预提交的接收缓冲区必须直接在IOBuf的Block里面，被存放于RdmaEndpoint::_rbuf。注意，接收端预提交的每一段Block，有一个固定的大小（recv_block_size）。发送端发送时，一个请求最多只能有这么大，否则接收端则无法成功接收。
+RdmaEndpoint数据传输逻辑的第一个重要特性是零拷贝。要发送的所有数据默认都存放在IOBuf的Block中，因此所发送的Block需要等到发送CQE触发后才可以释放，这些Block的引用被存放于RdmaEndpoint::_sbuf中。而要实现接收零拷贝，则需要确保接受端所预提交的接收缓冲区必须直接在IOBuf的Block里面，被存放于RdmaEndpoint::_rbuf。注意，接收端预提交的每一段Block，有一个固定的大小（recv_block_size）。发送端发送时，一个请求最多只能有这么大，否则接收端则无法成功接收。
 
 RdmaEndpoint数据传输逻辑的第二个重要特性是滑动窗口流控。这一流控机制是为了避免发送端持续在发送，其速度超过了接收端处理的速度。TCP传输中也有类似的逻辑，但是是由内核协议栈来实现的。RdmaEndpoint内实现了这一流控机制，通过接收端显式回复ACK来确认接收端处理完毕。为了减少ACK本身的开销，让ACK以立即数形式返回，可以被附在数据消息里。
 
@@ -52,26 +52,26 @@ RDMA支持事件驱动和轮询两种模式，默认是事件驱动模式，通
 # 参数
 
 可配置参数说明：
-* rdma_trace_verbose: 日志中打印RDMA建连相关信息，默认false
-* rdma_recv_zerocopy: 是否启用接收零拷贝，默认true
-* rdma_zerocopy_min_size: 接收零拷贝最小的msg大小，默认512B
-* rdma_recv_block_type: 为接收数据预准备的block类型，分为三类default(8KB)/large(64KB)/huge(2MB)，默认为default
-* rdma_prepared_qp_size: 程序启动预生成的QP的大小，默认128
-* rdma_prepared_qp_cnt: 程序启动预生成的QP的数量，默认1024
-* rdma_max_sge: 允许的最大发送SGList长度，默认为0，即采用硬件所支持的最大长度
-* rdma_sq_size: SQ大小，默认128
-* rdma_rq_size: RQ大小，默认128
-* rdma_cqe_poll_once: 从CQ中一次性poll出的CQE数量，默认32
-* rdma_gid_index: 使用本地GID表中的Index，默认为-1，即选用最大的可用GID Index
-* rdma_port: 使用IB设备的port number，默认为1
-* rdma_device: 使用IB设备的名称，默认为空，即使用第一个active的设备
-* rdma_memory_pool_initial_size_mb: 内存池的初始大小，单位MB，默认1024
-* rdma_memory_pool_increase_size_mb: 内存池每次动态增长的大小，单位MB，默认1024
-* rdma_memory_pool_max_regions: 最大的内存池块数，默认16
-* rdma_memory_pool_buckets: 内存池中为避免竞争采用的bucket数目，默认为4
-* rdma_memory_pool_tls_cache_num: 内存池中thread local的缓存block数目，默认为128
-* rdma_use_polling: 是否使用RDMA的轮询模式，默认false
-* rdma_poller_num: 轮询模式下的poller数目，默认1
-* rdma_poller_yield: 轮询模式下的poller是否主动放弃CPU，默认是false
-* rdma_edisp_unsched: 让事件驱动器不可以被调度，默认是false
-* rdma_disable_bthread: 禁用bthread，默认是false
+* rdma_trace_verbose: 日志中打印RDMA建连相关信息，默认false。
+* rdma_recv_zerocopy: 是否启用接收零拷贝，默认true。
+* rdma_zerocopy_min_size: 接收零拷贝最小的msg大小，默认512B。
+* rdma_recv_block_type: 为接收数据预准备的block类型，分为三类default(8KB)/large(64KB)/huge(2MB)，默认为default。
+* rdma_prepared_qp_size: 程序启动预生成的QP的大小，默认128。
+* rdma_prepared_qp_cnt: 程序启动预生成的QP的数量，默认1024。
+* rdma_max_sge: 允许的最大发送SGList长度，默认为0，即采用硬件所支持的最大长度。
+* rdma_sq_size: SQ大小，默认128。
+* rdma_rq_size: RQ大小，默认128。
+* rdma_cqe_poll_once: 从CQ中一次性poll出的CQE数量，默认32。
+* rdma_gid_index: 使用本地GID表中的Index，默认为-1，即选用最大的可用GID Index。
+* rdma_port: 使用IB设备的port number，默认为1。
+* rdma_device: 使用IB设备的名称，默认为空，即使用第一个active的设备。
+* rdma_memory_pool_initial_size_mb: 内存池的初始大小，单位MB，默认1024。
+* rdma_memory_pool_increase_size_mb: 内存池每次动态增长的大小，单位MB，默认1024。
+* rdma_memory_pool_max_regions: 最大的内存池块数，默认3。
+* rdma_memory_pool_buckets: 内存池中为避免竞争采用的bucket数目，默认为4。
+* rdma_memory_pool_tls_cache_num: 内存池中thread local的缓存block数目，默认为128。
+* rdma_use_polling: 是否使用RDMA的轮询模式，默认false。
+* rdma_poller_num: 轮询模式下的poller数目，默认1。
+* rdma_poller_yield: 轮询模式下的poller是否主动放弃CPU，默认是false。
+* rdma_edisp_unsched: 让事件驱动器不可以被调度，默认是false。
+* rdma_disable_bthread: 禁用bthread，默认是false。

docs/en/rdma.md

@@ -35,7 +35,7 @@ RDMA does not use socket API like TCP. However, the brpc::Socket class is still
 
 brpc uses RDMA RC mode. Every RdmaEndpoint has its own QP. Before establishing RDMA connection, a TCP connection is necessary to exchange some information such as GID and QPN. We call this procedure handshake. Since handshake needs TCP connection, the TCP fd in the corresponding Socket is still valid. The handshake procedure is completed in the AppConnect way in brpc. The TCP connection will keep in EST state but not be used for data transmission after RDMA connection is established. Once the TCP connection is closed, the corresponding RDMA connection will be set error.
 
-The first key feature in RdmaEndpoint data transmission is zero copy. All data which need to transmit is in the Blocks of IOBuf. Thus all the Blocks need to be released after the remote side completes the receiving. The reference of these Blocks are stored in RdmaEndpoint::_sbuf. In order to realize receiving zero copy, the receive side must post receive buffers in Blocks of IOBuf, which are stored in RdmaEndpoint::_rbuf. Note that all the Blocks posted in the receive side has a fixed size (recv_block_size). The transmit side can only send message smaller than that. Otherwise the receive side cannot receive data successfully.
+The first key feature in RdmaEndpoint data transmission is zero copy. All data which need to transmit is in the Blocks of IOBuf. Thus all the Blocks need to be released after the sent CQEs are triggered. The reference of these Blocks are stored in RdmaEndpoint::_sbuf. In order to realize receiving zero copy, the receive side must post receive buffers in Blocks of IOBuf, which are stored in RdmaEndpoint::_rbuf. Note that all the Blocks posted in the receive side has a fixed size (recv_block_size). The transmit side can only send message smaller than that. Otherwise the receive side cannot receive data successfully.
 
 The second key feature in RdmaEndpoint data transmission is sliding window flow control. The flow control is to avoid fast transmit side overwhelming slow receive side. TCP has similar mechanism in kernel TCP stack. RdmaEndpoint implements this mechanism with explicit ACKs from receive side. to reduce the overhead of ACKs, the ACK number can be piggybacked in ordinary data message as immediate data.
 
@@ -50,21 +50,26 @@ RDMA is hardware-related. It has some different concepts such as device, port, G
 # Parameters
 
 Configurable parameters:
-* rdma_trace_verbose: to print RDMA connection information in log，default is false
-* rdma_recv_zerocopy: enable zero copy in receive side，default is true
-* rdma_zerocopy_min_size: the min message size for receive zero copy (in Byte)，default is 512
-* rdma_recv_block_type: the block type used for receiving, can be default(8KB)/large(64KB)/huge(2MB)，default is default
-* rdma_prepared_qp_size: the size of QPs created at the beginning of the application，default is 128
-* rdma_prepared_qp_cnt: the number of QPs created at the beginning of the application，default is 1024
-* rdma_max_sge: the max length of sglist, default is 0, which is the max length allowed by the device
-* rdma_sq_size: the size of SQ，default is 128
-* rdma_rq_size: the size of RQ，default is 128
-* rdma_cqe_poll_once: the number of CQE pooled from CQ once，default is 32
-* rdma_gid_index: the index of local GID table used，default is -1，which is the maximum GID index
-* rdma_port: the port number used，default is 1
-* rdma_device: the IB device name，default is empty，which is the first active device
-* rdma_memory_pool_initial_size_mb: the initial region size of RDMA memory pool (in MB)，default is 1024
-* rdma_memory_pool_increase_size_mb: the step increase region size of RDMA memory pool (in MB)，default is 1024
-* rdma_memory_pool_max_regions: the max number of regions in RDMA memory pool，default is 16
-* rdma_memory_pool_buckets: the number of buckets for avoiding mutex contention in RDMA memory pool，default is 4
-* rdma_memory_pool_tls_cache_num: the number of thread local cached blocks in RDMA memory pool，default is 128
+* rdma_trace_verbose: to print RDMA connection information in log，default is false.
+* rdma_recv_zerocopy: enable zero copy in receive side，default is true.
+* rdma_zerocopy_min_size: the min message size for receive zero copy (in Byte)，default is 512.
+* rdma_recv_block_type: the block type used for receiving, can be default(8KB)/large(64KB)/huge(2MB)，default is default.
+* rdma_prepared_qp_size: the size of QPs created at the beginning of the application，default is 128.
+* rdma_prepared_qp_cnt: the number of QPs created at the beginning of the application，default is 1024.
+* rdma_max_sge: the max length of sglist, default is 0, which is the max length allowed by the device.
+* rdma_sq_size: the size of SQ，default is 128.
+* rdma_rq_size: the size of RQ，default is 128.
+* rdma_cqe_poll_once: the number of CQE pooled from CQ once，default is 32.
+* rdma_gid_index: the index of local GID table used，default is -1，which is the maximum GID index.
+* rdma_port: the port number used，default is 1.
+* rdma_device: the IB device name，default is empty，which is the first active device.
+* rdma_memory_pool_initial_size_mb: the initial region size of RDMA memory pool (in MB)，default is 1024.
+* rdma_memory_pool_increase_size_mb: the step increase region size of RDMA memory pool (in MB)，default is 1024.
+* rdma_memory_pool_max_regions: the max number of regions in RDMA memory pool，default is 3.
+* rdma_memory_pool_buckets: the number of buckets for avoiding mutex contention in RDMA memory pool，default is 4.
+* rdma_memory_pool_tls_cache_num: the number of thread local cached blocks in RDMA memory pool，default is 128.
+* rdma_use_polling: Whether to use RDMA polling mode, default is false.
+* rdma_poller_num: The number of pollers in polling mode, default is 1.
+* rdma_poller_yield: Whether pollers in polling mode voluntarily relinquish the CPU, default is false.
+* rdma_edisp_unsched`: Prevents the event driver from being scheduled, default is false.
+* rdma_disable_bthread: Disables bthread, default is false.