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2018-10-03erts: Remove "dynamic" lock order supportSverker Eriksson
2018-10-03erts: Add lock order check of erl_db_catree base nodesSverker Eriksson
Lock order is key term order, so each base node needs its own key if lock check is enabled.
2018-09-05Add a more scalable ETS ordered_set implementationKjell Winblad
The current ETS ordered_set implementation can quickly become a scalability bottleneck on multicore machines when an application updates an ordered_set table from concurrent processes [1][2]. The current implementation is based on an AVL tree protected from concurrent writes by a single readers-writer lock. Furthermore, the current implementation has an optimization, called the stack optimization [3], that can improve the performance when only a single process accesses a table but can cause bad scalability even in read-only scenarios. It is possible to pass the option {write_concurrency, true} to ets:new/2 when creating an ETS table of type ordered_set but this option has no effect for tables of type ordered_set without this commit. The new ETS ordered_set implementation, added by this commit, is only activated when one passes the options ordered_set and {write_concurrency, true} to the ets:new/2 function. Thus, the previous ordered_set implementation (from here on called the default implementation) can still be used in applications that do not benefit from the new implementation. The benchmark results on the following web page show that the new implementation is many times faster than the old implementation in some scenarios and that the old implementation is still better than the new implementation in some scenarios. http://winsh.me/ets_catree_benchmark/ets_ca_tree_benchmark_results.html The new implementation is expected to scale better than the default implementation when concurrent processes use the following ETS operations to operate on a table: delete/2, delete_object/2, first/1, insert/2 (single object), insert_new/2 (single object), lookup/2, lookup_element/2, member/2, next/2, take/2 and update_element/3 (single object). Currently, the new implementation does not have scalable support for the other operations (e.g., select/2). However, when these operations are used infrequently, the new implantation may still scale better than the default implementation as the benchmark results at the URL above shows. Description of the New Implementation ---------------------------------- The new implementation is based on a data structure which is called the contention adapting search tree (CA tree for short). The following publication contains a detailed description of the CA tree: A Contention Adapting Approach to Concurrent Ordered Sets Journal of Parallel and Distributed Computing, 2018 Kjell Winblad and Konstantinos Sagonas https://doi.org/10.1016/j.jpdc.2017.11.007 http://www.it.uu.se/research/group/languages/software/ca_tree/catree_proofs.pdf A discussion of how the CA tree can be used as an ETS back-end can be found in another publication [1]. The CA tree is a data structure that dynamically changes its synchronization granularity based on detected contention. Internally, the CA tree uses instances of a sequential data structure to store items. The CA tree implementation contained in this commit uses the same AVL tree implementation as is used for the default ordered set implementation. This AVL tree implementation is reused so that much of the existing code to implement the ETS operations can be reused. Tests ----- The ETS tests in `lib/stdlib/test/ets_SUITE.erl` have been extended to also test the new ordered_set implementation. The function ets_SUITE:throughput_benchmark/0 has also been added to this file. This function can be used to measure and compare the performance of the different ETS table types and options. This function writes benchmark data to standard output that can be visualized by the HTML page `lib/stdlib/test/ets_SUITE_data/visualize_throughput.html`. [1] More Scalable Ordered Set for ETS Using Adaptation. In Thirteenth ACM SIGPLAN workshop on Erlang (2014). Kjell Winblad and Konstantinos Sagonas. https://doi.org/10.1145/2633448.2633455 http://www.it.uu.se/research/group/languages/software/ca_tree/erlang_paper.pdf [2] On the Scalability of the Erlang Term Storage In Twelfth ACM SIGPLAN workshop on Erlang (2013) Kjell Winblad, David Klaftenegger and Konstantinos Sagonas https://doi.org/10.1145/2505305.2505308 http://winsh.me/papers/erlang_workshop_2013.pdf [3] The stack optimization works by keeping one preallocated stack instance in every ordered_set table. This stack is updated so that it contains the search path in some read operations (e.g., ets:next/2). This makes it possible for a subsequent ets:next/2 to avoid traversing some nodes in some cases. Unfortunately, the preallocated stack needs to be flagged so that it is not updated concurrently by several threads which cause bad scalability.
2018-06-18Update copyright yearHenrik Nord
2018-04-13erts: Add erts_debug:lc_graph/0Sverker Eriksson
Run debug VM or config with --enable-lock-checking. Exercise VM and then run erts_debug:lc_graph(). to create a file "lc_graph.<pid>" in current working directory.
2017-07-25Merge branch 'maint'John Högberg
2017-07-17erts: Replace usage of all erts_smp prefixes to just ertsLukas Larsson
2017-07-17erts: Remove ERTS_SMP and USE_THREAD definesLukas Larsson
This refactor was done using the unifdef tool like this: for file in $(find erts/ -name *.[ch]); do unifdef -t -f defile -o $file $file; done where defile contained: #define ERTS_SMP 1 #define USE_THREADS 1 #define DDLL_SMP 1 #define ERTS_HAVE_SMP_EMU 1 #define SMP 1 #define ERL_BITS_REENTRANT 1 #define ERTS_USE_ASYNC_READY_Q 1 #define FDBLOCK 1 #undef ERTS_POLL_NEED_ASYNC_INTERRUPT_SUPPORT #define ERTS_POLL_ASYNC_INTERRUPT_SUPPORT 0 #define ERTS_POLL_USE_WAKEUP_PIPE 1 #define ERTS_POLL_USE_UPDATE_REQUESTS_QUEUE 1 #undef ERTS_HAVE_PLAIN_EMU #undef ERTS_SIGNAL_STATE
2017-07-11Use erl_lock_flags in lock checkingJohn Högberg
2016-03-15update copyright-yearHenrik Nord
2015-06-18Change license text to APLv2Bruce Yinhe
2014-02-24erts: Make source file info available in lcLukas Larsson
2012-12-07Merge branch 'rickard/port-optimizations/OTP-10336' into ↵Rickard Green
rickard/r16/port-optimizations/OTP-10336 * rickard/port-optimizations/OTP-10336: Change annotate level for emacs-22 in cerl Update etp-commands Add documentation on communication in Erlang Add support for busy port message queue Add driver callback epilogue Implement true asynchronous signaling between processes and ports Add erl_drv_[send|output]_term Move busy port flag Use rwlock for driver list Optimize management of port tasks Improve configuration of process and port tables Remove R9 compatibility features Use ptab functionality also for ports Prepare for use of ptab functionality also for ports Atomic port state Generalize process table implementation Implement functionality for delaying thread progress from unmanaged threads Conflicts: erts/doc/src/erl_driver.xml erts/doc/src/erlang.xml erts/emulator/beam/beam_bif_load.c erts/emulator/beam/beam_bp.c erts/emulator/beam/beam_emu.c erts/emulator/beam/bif.c erts/emulator/beam/copy.c erts/emulator/beam/erl_alloc.c erts/emulator/beam/erl_alloc.types erts/emulator/beam/erl_bif_info.c erts/emulator/beam/erl_bif_port.c erts/emulator/beam/erl_bif_trace.c erts/emulator/beam/erl_init.c erts/emulator/beam/erl_message.c erts/emulator/beam/erl_port_task.c erts/emulator/beam/erl_process.c erts/emulator/beam/erl_process.h erts/emulator/beam/erl_process_lock.c erts/emulator/beam/erl_trace.c erts/emulator/beam/export.h erts/emulator/beam/global.h erts/emulator/beam/io.c erts/emulator/sys/unix/sys.c erts/emulator/sys/vxworks/sys.c erts/emulator/test/port_SUITE.erl erts/etc/unix/cerl.src erts/preloaded/ebin/erlang.beam erts/preloaded/ebin/prim_inet.beam erts/preloaded/src/prim_inet.erl lib/hipe/cerl/erl_bif_types.erl lib/kernel/doc/src/inet.xml lib/kernel/src/inet.erl
2012-12-03Use ptab functionality also for portsRickard Green
2012-11-23Update copyright yearsBjörn-Egil Dahlberg
2012-11-16erts: Suppress lock assertion when dumping a crashBjörn-Egil Dahlberg
2011-05-09Expand the use of high memory allocation in halfword emulatorSverker Eriksson
Also add 'low' field in system_info(allocator) SHORT_LIVED is still in low memory
2011-03-11Update copyright yearsBjörn-Egil Dahlberg
2010-08-10Rewrite ethread libraryRickard Green
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.
2009-11-20The R13B03 release.OTP_R13B03Erlang/OTP
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