X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=README;h=b3839e1a614a134c4960cc96824cefca83078d69;hp=d454757fceffa30e7622d64dfee07290537bb0ee;hb=fdf01eeda9f634a32db3fc90cd342da08d7a259d;hpb=c51e75e62494c2f6aae4a88aa4499444716846d7

diff --git a/README b/README
index d454757..b3839e1 100644
--- a/README
+++ b/README
@@ -9,20 +9,24 @@ BUILDING
 	make
 	make install
 
-	Note:	Forcing 32-bit build:
-		* CFLAGS=-m32 ./configure
+	Hints:	Forcing 32-bit build:
+		* CFLAGS="-m32 -g -O2" ./configure
 
 		Forcing 64-bit build:
-		* CFLAGS=-m64 ./configure
+		* CFLAGS="-m64 -g -O2" ./configure
+
+		Forcing a 32-bit build with 386 backward compatibility:
+		* CFLAGS="-m32 -g -O2" ./configure --host=i386-pc-linux-gnu
+
+		Forcing a 32-bit build for Sparcv9 (typical for Sparc v9)
+		* CFLAGS="-m32 -Wa,-Av9a -g -O2" ./configure
 
 ARCHITECTURES SUPPORTED
 -----------------------
 
-Currently, x86 (only Pentium and +), x86 64, PowerPC 32/64 and S390 are
-supported. The current use of sys_futex() makes it Linux-dependent, although
-this portability limitation might go away in a near future by using the pthread
-cond vars. Also, the restriction against i386 and i486 might go away if we
-integrate some of glibc runtime CPU-detection tests.
+Currently, x86 (i386, i486, i586, i686), x86 64-bit, PowerPC 32/64, S390, S390x
+and Sparcv9 32/64 are supported. Only tested on Linux so far, but should
+theoretically work on other operating systems.
 
 QUICK START GUIDE
 -----------------
@@ -40,19 +44,11 @@ Usage of liburcu
 
 	* #include <urcu.h>
 	* Link the application with "-lurcu".
-	* This is the preferred version of the library, both in terms of speed
-	  and flexibility. Requires a signal, typically SIGUSR1. Can be
-	  overridden with -DSIGURCU by modifying Makefile.build.inc.
-
-Usage of liburcu-mb
-
-	* #include <urcu.h>
-	* Compile any _LGPL_SOURCE code using this library with "-DURCU_MB".
-	* Link with "-lurcu-mb".
-	* This version of the urcu library does not need to
-	  reserve a signal number. URCU_MB uses full memory barriers for
-	  readers. This eliminates the need for signals but results in slower
-	  reads.
+	* This is the preferred version of the library, in terms of
+	  grace-period detection speed, read-side speed and flexibility.
+	  Dynamically detects kernel support for sys_membarrier(). Falls back
+	  on urcu-mb scheme if support is not present, which has slower
+	  read-side.
 
 Usage of liburcu-qsbr
 
@@ -64,13 +60,29 @@ Usage of liburcu-qsbr
 	  the threads are not active. It provides the fastest read-side at the
 	  expense of more intrusiveness in the application code.
 
+Usage of liburcu-mb
+
+	* #include <urcu.h>
+	* Compile any _LGPL_SOURCE code using this library with "-DRCU_MB".
+	* Link with "-lurcu-mb".
+	* This version of the urcu library uses memory barriers on the writer
+	  and reader sides. This results in faster grace-period detection, but
+	  results in slower reads.
+
+Usage of liburcu-signal
+
+	* #include <urcu-signal.h>
+	* Link the application with "-lurcu-signal".
+	* Version of the library that requires a signal, typically SIGUSR1. Can
+	  be overridden with -DSIGRCU by modifying Makefile.build.inc.
+
 Usage of liburcu-bp
 
 	* #include <urcu-bp.h>
 	* Link with "-lurcu-bp".
 	* The BP library flavor stands for "bulletproof". It is specifically
 	  designed to help tracing library to hook on applications without
-	  requiring to modify these applications. urcu_init(),
+	  requiring to modify these applications. rcu_init(),
 	  rcu_register_thread() and rcu_unregister_thread() all become nops.
 	  The state is dealt with by the library internally at the expense of
 	  read-side and write-side performance.
@@ -98,11 +110,20 @@ Writing
 Usage of liburcu-defer
 
 	* #include <urcu-defer.h>
-	* Link with "-lurcu-defer"
-	* Provides call_rcu() primitive to enqueue delayed callbacks. Queued
+	* Link with "-lurcu-defer", and also with one of the urcu library
+	  (either urcu, urcu-bp, urcu-mb or urcu-qsbr).
+	* Provides defer_rcu() primitive to enqueue delayed callbacks. Queued
 	  callbacks are executed in batch periodically after a grace period.
-	  Do _not_ use call_rcu() within a read-side critical section, because
+	  Do _not_ use defer_rcu() within a read-side critical section, because
 	  it may call synchronize_rcu() if the thread queue is full.
+	* Provides defer_rcu_ratelimit() primitive, which acts just like
+	  defer_rcu(), but takes an additional rate limiter callback forcing
+	  synchronized callback execution of the limiter returns non-zero.
+	* Requires that rcu_defer_barrier() must be called in library destructor
+	  if a library queues callbacks and is expected to be unloaded with
+	  dlclose().
+	* Its API is currently experimental. It may change in future library
+	  releases.
 
 Being careful with signals
 
@@ -136,3 +157,13 @@ Usage of DEBUG_YIELD
 
 	DEBUG_YIELD is used to add random delays in the code for testing
 	purposes.
+
+SMP support
+
+	By default the library is configured to use synchronization primitives
+	adequate for SMP systems. On uniprocessor systems, support for SMP
+	systems can be disabled with:
+
+		./configure --disable-smp-support
+
+	theoretically yielding slightly better performance.