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The old time API is based on erlang:now/0. The major issue with
erlang:now/0 is that it was intended to be used for so many
unrelated things. This tied these unrelated operations together
and unnecessarily caused performance, scalability as well as
accuracy, and precision issues for operations that do not need
to have such issues. The new API spreads different functionality
over multiple functions in order to improve on this.
The new API consists of a number of new BIFs:
- erlang:convert_time_unit/3
- erlang:monotonic_time/0
- erlang:monotonic_time/1
- erlang:system_time/0
- erlang:system_time/1
- erlang:time_offset/0
- erlang:time_offset/1
- erlang:timestamp/0
- erlang:unique_integer/0
- erlang:unique_integer/1
- os:system_time/0
- os:system_time/1
and a number of extensions of existing BIFs:
- erlang:monitor(time_offset, clock_service)
- erlang:system_flag(time_offset, finalize)
- erlang:system_info(os_monotonic_time_source)
- erlang:system_info(time_offset)
- erlang:system_info(time_warp_mode)
- erlang:system_info(time_correction)
- erlang:system_info(start_time)
See the "Time and Time Correction in Erlang" chapter of the
ERTS User's Guide for more information.
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This simplified debugging on OSE and also limits the number of ppdata
keys that are created when beam is restarted.
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* Add new suspend, location, and port_locks options to erts_debug:lock_counters.
* Init and destroy lock counting for processes and ports as appropriate.
Conflicts:
erts/emulator/beam/erl_bif_info.c
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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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* egil/lcnt:
Add test suite for lcnt in tools
Add lcnt:rt_opt/1 bindings to erts_debug
Add runtime option to enable/disable lcnt stats
Add auto width on string output
Add lcnt documentation
Add lock profiling tool
OTP-8424 Add lock profiling tool.
The Lock profiling tool, lcnt, can make use of the internal lock
statistics when the runtime system is built with this feature
enabled.
This provides a mechanism to examine potential lock bottlenecks
within the runtime itself.
- Add erts_debug:lock_counters({copy_save, bool()}). This option
enables or disables statistics saving for destroyed processes and
ets-tables. Enabling this might consume a lot of memory.
- Add id-numbering for lock classes which is otherwise undefined.
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Add erts_debug:lock_counters({copy_save, bool()}). This option
enables or disables statistics saving for destroyed processes and
ets-tables. Enabling this might consume a lot of memory.
Add id-numbering for lock classes which is otherwise undefined.
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