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The commit adb5dc0090bc419e2c4c1250653badbddeb6263b (ETHR_FORCE_INLINE)
broke some platforms without adequate thread support.
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Add initial support for dirty schedulers.
There are two types of dirty schedulers: CPU schedulers and I/O
schedulers. By default, there are as many dirty CPU schedulers as there are
normal schedulers and as many dirty CPU schedulers online as normal
schedulers online. There are 10 dirty I/O schedulers (similar to the choice
of 10 as the default for async threads).
By default, dirty schedulers are disabled and conditionally compiled
out. To enable them, you must pass --enable-dirty-schedulers to the
top-level configure script when building Erlang/OTP.
Current dirty scheduler support requires the emulator to be built with SMP
support. This restriction will be lifted in the future.
You can specify the number of dirty schedulers with the command-line
options +SDcpu (for dirty CPU schedulers) and +SDio (for dirty I/O
schedulers). The +SDcpu option is similar to the +S option in that it takes
two numbers separated by a colon: C1:C2, where C1 specifies the number of
dirty schedulers available and C2 specifies the number of dirty schedulers
online. The +SDPcpu option allows numbers of dirty CPU schedulers available
and dirty CPU schedulers online to be specified as percentages, similar to
the existing +SP option for normal schedulers. The number of dirty CPU
schedulers created and dirty CPU schedulers online may not exceed the
number of normal schedulers created and normal schedulers online,
respectively. The +SDio option takes only a single number specifying the
number of dirty I/O schedulers available and online. There is no support
yet for programmatically changing at run time the number of dirty CPU
schedulers online via erlang:system_flag/2. Also, changing the number of
normal schedulers online via erlang:system_flag(schedulers_online,
NewSchedulersOnline) should ensure that there are no more dirty CPU
schedulers than normal schedulers, but this is not yet implemented. You can
retrieve the number of dirty schedulers by passing dirty_cpu_schedulers,
dirty_cpu_schedulers_online, or dirty_io_schedulers to
erlang:system_info/1.
Currently only NIFs are able to access dirty scheduler
functionality. Neither drivers nor BIFs currently support dirty
schedulers. This restriction will be addressed in the future.
If dirty scheduler support is present in the runtime, the initial status
line Erlang prints before presenting its interactive prompt will include
the indicator "[ds:C1:C2:I]" where "ds" indicates "dirty schedulers", "C1"
indicates the number of dirty CPU schedulers available, "C2" indicates the
number of dirty CPU schedulers online, and "I" indicates the number of
dirty I/O schedulers.
Document The dirty NIF API in the erl_nif man page. The API closely follows
Rickard Green's presentation slides from his talk "Future Extensions to the
Native Interface", presented at the 2011 Erlang Factory held in the San
Francisco Bay Area. Rickard's slides are available online at
http://bit.ly/1m34UHB .
Document the new erl command-line options, the additions to
erlang:system_info/1, and also add the erlang:system_flag/2 dirty scheduler
documentation even though it's not yet implemented.
To determine whether the dirty NIF API is available, native code can check
to see whether the C preprocessor macro ERL_NIF_DIRTY_SCHEDULER_SUPPORT is
defined. To check if dirty schedulers are available at run time, native
code can call the boolean enif_have_dirty_schedulers() function, and Erlang
code can call erlang:system_info(dirty_cpu_schedulers), which raises
badarg if no dirty scheduler support is available.
Add a simple dirty NIF test to the emulator NIF suite.
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With silent rules, the output of make is less verbose and compilation
warnings are easier to spot. Silent rules are disabled by default and
can be disabled or enabled at will by make V=0 and make V=1.
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OTP-10106
OTP-10107
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* Make generate and depend.mk automatically.
* Do not make depend.mk for targets clean and generate.
* Remove old replaced CREATE_DIRS cruft.
* Fiercer remove by target clean.
* Move depend.mk to Target/Type/Flavor directory.
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Use a make timestamp file to condense dependencies to some
part(s) of erts/lib_src build results.
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Still does not run, just compiles.
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The ethread atomics API now also provide double word size atomics.
Double word size atomics are implemented using native atomic
instructions on x86 (when the cmpxchg8b instruction is available)
and on x86_64 (when the cmpxchg16b instruction is available). On
other hardware where 32-bit atomics or word size atomics are
available, an optimized fallback is used; otherwise, a spinlock,
or a mutex based fallback is used.
The ethread library now performs runtime tests for presence of
hardware features, such as for example SSE2 instructions, instead
of requiring this to be determined at compile time.
There are now functions implementing each atomic operation with the
following implied memory barrier semantics: none, read, write,
acquire, release, and full. Some of the operation-barrier
combinations aren't especially useful. But instead of filtering
useful ones out, and potentially miss a useful one, we implement
them all.
A much smaller set of functionality for native atomics are required
to be implemented than before. More or less only cmpxchg and a
membar macro are required to be implemented for each atomic size.
Other functions will automatically be constructed from these. It is,
of course, often wise to implement more that this if possible from a
performance perspective.
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Large parts of the ethread library have been rewritten. The
ethread library is an Erlang runtime system internal, portable
thread library used by the runtime system itself.
Most notable improvement is a reader optimized rwlock
implementation which dramatically improve the performance of
read-lock/read-unlock operations on multi processor systems by
avoiding ping-ponging of the rwlock cache lines. The reader
optimized rwlock implementation is used by miscellaneous
rwlocks in the runtime system that are known to be read-locked
frequently, and can be enabled on ETS tables by passing the
`{read_concurrency, true}' option upon table creation. See the
documentation of `ets:new/2' for more information.
The ethread library can now also use the libatomic_ops library
for atomic memory accesses. This makes it possible for the
Erlang runtime system to utilize optimized atomic operations
on more platforms than before. Use the
`--with-libatomic_ops=PATH' configure command line argument
when specifying where the libatomic_ops installation is
located. The libatomic_ops library can be downloaded from:
http://www.hpl.hp.com/research/linux/atomic_ops/
The changed API of the ethread library has also caused
modifications in the Erlang runtime system. Preparations for
the to come "delayed deallocation" feature has also been done
since it depends on the ethread library.
Note: When building for x86, the ethread library will now use
instructions that first appeared on the pentium 4 processor. If
you want the runtime system to be compatible with older
processors (back to 486) you need to pass the
`--enable-ethread-pre-pentium4-compatibility' configure command
line argument when configuring the system.
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Support for using gcc's built-in functions for atomic memory access has
been added. This functionallity will be used if available and no other
native atomic implementation in ERTS is available.
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environment after a number of bugs are fixed and some features
are added in the documentation build process.
- The arity calculation is updated.
- The module prefix used in the function names for bif's are
removed in the generated links so the links will look like
http://www.erlang.org/doc/man/erlang.html#append_element-2
instead of
http://www.erlang.org/doc/man/erlang.html#erlang:append_element-2
- Enhanced the menu positioning in the html documentation when a
new page is loaded.
- A number of corrections in the generation of man pages (thanks
to Sergei Golovan)
- Moved some man pages to more apropriate sections, pages in
section 4 moved to 5 and pages in 6 moved to 7.
- The legal notice is taken from the xml book file so OTP's
build process can be used for non OTP applications.
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checking if CC equaled gcc. That is, the makefiles failed to
detect gcc C compilers with other command line names than gcc.
`configure' now substitute GCC into the makefiles. If CC is a gcc
C compiler, GCC will have the value yes. (Thanks to
Jean-S�bastien P�dron)
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