X-Git-Url: http://git.lttng.org/?p=userspace-rcu.git;a=blobdiff_plain;f=README;h=8d0b18e73e691bf282e1ad0c345ee07dfbc9f6e8;hp=81afe0e2757c8bceabef7c50ff4102d0600aa8d3;hb=6425e2eea5b38186d86aca9b5deb5c642e06eb0a;hpb=207e8061ddfafbdd0502fb6da4896b4c40a49253 diff --git a/README b/README index 81afe0e..8d0b18e 100644 --- a/README +++ b/README @@ -27,9 +27,10 @@ ARCHITECTURES SUPPORTED ----------------------- Currently, Linux x86 (i386, i486, i586, i686), x86 64-bit, PowerPC 32/64, -S390, S390x, ARM, Alpha, ia64 and Sparcv9 32/64 are supported. Tested on -Linux, FreeBSD 8.2/9.0, and Cygwin. Should also work on: Android, NetBSD 5, -OpenBSD, Darwin (more testing needed before claiming support for these OS). +S390, S390x, ARM, MIPS, Alpha, ia64 and Sparcv9 32/64 are supported. +Tested on Linux, FreeBSD 8.2/8.3/9.0/9.1/10.0 i386/amd64, and Cygwin. +Should also work on: Android, NetBSD 5, OpenBSD, Darwin (more testing +needed before claiming support for these OS). Linux ARM depends on running a Linux kernel 2.6.15 or better, GCC 4.4 or better. @@ -48,6 +49,15 @@ supported, with the following exceptions: support. For ARM this was introduced with gcc 4.4: http://gcc.gnu.org/gcc-4.4/changes.html +Clang version 3.0 (based on LLVM 3.0) is supported. + +Building on MacOS X (Darwin) requires a work-around for processor +detection: + # 32-bit + ./configure --build=i686-apple-darwin11 + # 64-bit + ./configure --build=x86_64-apple-darwin11 + For developers using the git tree: This source tree is based on the autotools suite from GNU to simplify @@ -73,11 +83,11 @@ API See the relevant API documentation files in doc/. The APIs provided by Userspace RCU are, by prefix: -- rcu_ : Read-Copy Update +- rcu_ : Read-Copy Update (see doc/rcu-api.txt) - cmm_ : Concurrent Memory Model - caa_ : Concurrent Architecture Abstraction -- cds_ : Concurrent Data Structures -- uatomic_: Userspace Atomic +- cds_ : Concurrent Data Structures (see doc/cds-api.txt) +- uatomic_: Userspace Atomic (see doc/uatomic-api.txt) QUICK START GUIDE @@ -91,6 +101,19 @@ Usage of all urcu libraries instead of inlines, so your application can link with the library. * Linking with one of the libraries below is always necessary even for LGPL and GPL applications. + * Define URCU_INLINE_SMALL_FUNCTIONS before including Userspace RCU + headers if you want Userspace RCU to inline small functions (10 + lines or less) into the application. It can be used by applications + distributed under any kind of license, and does *not* make the + application a derived work of Userspace RCU. + + Those small inlined functions are guaranteed to match the library + content as long as the library major version is unchanged. + Therefore, the application *must* be compiled with headers matching + the library major version number. Applications using + URCU_INLINE_SMALL_FUNCTIONS may be unable to use debugging + features of Userspace RCU without being recompiled. + Usage of liburcu @@ -232,6 +255,47 @@ Interaction with mutexes should only be taken when the RCU reader thread is "offline" (this can be performed by calling rcu_thread_offline()). +Interaction with fork() + + Special care must be taken for applications performing fork() without + any following exec(). This is caused by the fact that Linux only clones + the thread calling fork(), and thus never replicates any of the other + parent thread into the child process. Most liburcu implementations + require that all registrations (as reader, defer_rcu and call_rcu + threads) should be released before a fork() is performed, except for the + rather common scenario where fork() is immediately followed by exec() in + the child process. The only implementation not subject to that rule is + liburcu-bp, which is designed to handle fork() by calling + rcu_bp_before_fork, rcu_bp_after_fork_parent and + rcu_bp_after_fork_child. + + Applications that use call_rcu() and that fork() without + doing an immediate exec() must take special action. The parent + must invoke call_rcu_before_fork() before the fork() and + call_rcu_after_fork_parent() after the fork(). The child + process must invoke call_rcu_after_fork_child(). + Even though these three APIs are suitable for passing to + pthread_atfork(), use of pthread_atfork() is *STRONGLY + DISCOURAGED* for programs calling the glibc memory allocator + (malloc(), calloc(), free(), ...) within call_rcu callbacks. + This is due to limitations in the way glibc memory allocator + handles calls to the memory allocator from concurrent threads + while the pthread_atfork() handlers are executing. + Combining e.g.: + * call to free() from callbacks executed within call_rcu worker + threads, + * executing call_rcu atfork handlers within the glibc pthread + atfork mechanism, + will sometimes trigger interesting process hangs. This usually + hangs on a memory allocator lock within glibc. + +Thread Local Storage (TLS) + + Userspace RCU can fall back on pthread_getspecific() to emulate + TLS variables on systems where it is not available. This behavior + can be forced by specifying --disable-compiler-tls as configure + argument. + Usage of DEBUG_RCU DEBUG_RCU is used to add internal debugging self-checks to the @@ -254,23 +318,23 @@ SMP support theoretically yielding slightly better performance. -Interaction with fork() +MAKE TARGETS +------------ - Special care must be taken for applications performing fork() without - any following exec(). This is caused by the fact that Linux only clones - the thread calling fork(), and thus never replicates any of the other - parent thread into the child process. Most liburcu implementations - require that all registrations (as reader, defer_rcu and call_rcu - threads) should be released before a fork() is performed, except for the - rather common scenario where fork() is immediately followed by exec() in - the child process. The only implementation not subject to that rule is - liburcu-bp, which is designed to handle fork() by calling - rcu_bp_before_fork, rcu_bp_after_fork_parent and - rcu_bp_after_fork_child. +In addition to the usual "make check" target, Userspace RCU features +"make regtest" and "make bench" targets. - Applications that use call_rcu() and that fork() without - doing an immediate exec() must take special action. The parent - must invoke call_rcu_before_fork() before the fork() and - call_rcu_after_fork_parent() after the fork(). The child - process must invoke call_rcu_after_fork_child(). - These three APIs are suitable for passing to pthread_atfork(). +make check: Short tests, meant to be run when rebuilding or porting + Userspace RCU. + +make regtest: Long (many hours) test, meant to be run when modifying + Userspace RCU or porting it to a new architecture or + operating system. + +make bench: Long (many hours) benchmarks. + +CONTACTS +-------- + +You can contact the maintainers on the following mailing list: +lttng-dev@lists.lttng.org