store anything in fi->fh. There are also some flags (direct_io, keep_cache) which the filesystem may set in fi, to change the way the file is opened. See fuse_file_info structure in for more details. If this request is answered with an error code of ENOSYS and FUSE_CAP_NO_OPEN_SUPPORT is set in fuse_conn_info.capable, this is treated as success and future calls to open and release will also 续读写等操作中依据该状态进行处理。 // cephfs Inode Fh.flags(cephfsFh struct Inode : RefCountedObject { ... std::set fhs; } // file handle for any open file state struct Fh { InodeRef inode; int _ref;

+------+------------+-----+----------------+---------+----------+ 字段 字节数 说明 type 1 操作类型，共有以下 2 类： SET (0X01)：ADD 和 UPDATE 都可以转换成 SET 操作 DEL (0X02)：当为 DEL 操作时，value_length 和 value 则为空 key_length 4 key 长度 key $key_length 消耗却更少，推介使用 protobuf 进行序列化 2、KVStore 将当前实现中的 MemoryDentryStorage 和 MemoryInodeStorage 抽象成一个 KVStore，对外提供 SET/GET/DEL 等接口，inode/dentry 均编码后以 key-value 的形式存入 KVStore 当前实现可先只实现 KVStore（提供方便 API），Raft 等可以后续接入（目前实现中持久化可以在 public braft::StateMachine { public: enum class OP_TYPE { OP_TYPE_SET, OP_TYPE_DEL, }; public: bool Init(); int Set(const std::string& key, const std::string& value); int Get(const

* * NOTE: For the time being, the maximum size of read requests© XXX Page 11 of 33 * must be set both here *and* passed to fuse_session_new() * using the ``-o max_read=`` mount option. At some 1, i.e. full * nano-second resolution. Filesystems supporting only second resolution * should set this to 1000000000. */ unsigned time_gran; /** * For future use.© XXX Page 14 of 33 */ unsigned /etc/login.defs # UMASK is the default umask value for pam_umask and is used by # useradd and newusers to set the mode of the new home directories. # 022 is the "historical" value in Debian for UMASK # 027, or

UCT ●Memory domain open/close ●Active message ●Memory get/put ●Memory atomic fetch, compare and set ●Tag match ●client/server模式的Listener, Ep(endpoint)26 UCP ●构建于uct之上，实现更加高级的功能,容易使用，但有一定开销。 ●UC ●指定了FEATURE_AM, 多线程共享39 命令行参数控制context的属性 ●--brpc_ucp_error_mode缺省是none，是的本地通讯使用shared memory成为可能 ●--brpc_set_cpu_latency 非-1, 设置intel cpu节电模式，可能减少硬 件延迟。 –/dev/cpu_dma_latency ●root特权 –Busy poll下不要开启，可能导致电耗过高、cpu降速40

(fuse_req_t req, fuse_ino_t ino, struct stat *attr, int to_set, struct fuse_file_info *fi); 根据inode id 找到inode id 对应的inode 结构（从缓存或者metaserver） 根据to_set字段设置相应的attr字段，然后持久化到metaserver，并更新本地缓存。 access 可先不支持，返回ENOSYS

com/abseil/abseil-cpp/tree/master/absl/c ontainer 实现了btree map和btree set，(Apache)。 google， https://code.google.com/archive/p/cpp-btree/， btree_map , btree_set, btree_multimap, and btree_multiset ，（ ） Apache B+tree

tcp_timeout_init • tcp_call_bpf(BPF_SOCK_OPS_TIMEOUT_INI T) • bpf_cgrougp_run_sock_ops • … • set_initial_rtoCurve的Cache模块 • 底层ext4⽂件系统作为cache • cache分为写cache与读cache，读/ 写cache独⽴配置 • 与底层⽂件关系 (filename

std::shared_ptr CacheWrite_; std::shared_ptr CacheRead_; std::set cachedObjName; // uint64_t maxCachedObj; // ? bthread::Mutex mtx_; }; class

the file directly maps to chunk, a 4TB file will consist of 256KB chunks when the chunk size is set to 16MB. There will be lots of pressure on KV storage, so we use two-level mapping and introduced