Age | Commit message (Collapse) | Author |
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A number of memory allocation optimizations have been implemented. Most
optimizations reduce contention caused by synchronization between
threads during allocation and deallocation of memory. Most notably:
* Synchronization of memory management in scheduler specific allocator
instances has been rewritten to use lock-free synchronization.
* Synchronization of memory management in scheduler specific
pre-allocators has been rewritten to use lock-free synchronization.
* The 'mseg_alloc' memory segment allocator now use scheduler specific
instances instead of one instance. Apart from reducing contention
this also ensures that memory allocators always create memory
segments on the local NUMA node on a NUMA system.
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Conflicts:
erts/aclocal.m4
erts/emulator/beam/erl_db.c
erts/emulator/sys/win32/sys.c
erts/include/internal/ethread_header_config.h.in
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All uses of the old deprecated atomic API in the runtime system
have been replaced with the use of the new atomic API. In a lot of
places this change imply a relaxation of memory barriers used.
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A race condition in erts_poll() could cause
delay of poll for I/O.
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Missing memory barriers in erts_poll() could cause the runtime system to
hang indefinitely.
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erts_poll_info_kp() [defined in erts/emulator/sys/common/erl_poll.c
via some name-mangling trickery] contains a code path that can end
up in an infinite loop, causing a livelock. There is a block of code
inside #if ERTS_POLL_USE_UPDATE_REQUESTS_QUEUE that is supposed to
iterate over a linked list of ErtsPollSetUpdateRequestsBlocks and
update two variables based on the sizes of these blocks. The bug is
that the loop forgets to advance the list pointer to the next element,
so if the loop is entered at all (the initial list pointer is non-NULL),
the thread falls into an infinite loop.
This patch, against R13B03 but applies fine to today's git, fixes the
bug by adding a statement to advance the list pointer in the loop.
All other loops over this list appear to be correct.
Thanks to Chetan Ahuja for the original report of a livelock problem
in erts_poll_info_kp().
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tile-cc 2.0.1.78377 when compiling the runtime system.
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