Age | Commit message (Collapse) | Author |
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At start of the VM a poll-set that the schedulers
will check is created where fds that have triggered
many (at the moment, many means 10) times without
being deselected inbetween. In this scheduler specific
poll-set fds do not use ONESHOT, which means that the
number of syscalls goes down dramatically for such fds.
This pollset is introduced in order to handle fds that
are used by the erlang distribution and that never
change their state from {active, true}.
This pollset only handles ready_input events,
ready_output is still handled by the poll threads.
During overload, polling the scheduler poll-set is done
on a 10ms timer.
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The poll thread does a lot of waking up and then going
back to sleep. A large part of the waking up is managing
thread progress and a large part of that was using thread
specific data to get the thread progress data pointer.
With this refactor the tpd is passed to each of the functions
which greatly decreases the number of ethr_get_tsd calls
which in turn halves the CPU usage of the poller thread in
certain scenarios.
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This is a hack to make the "noshell" option work; kqueue can poll
these fds but will not report EV_EOF. This may be common to all
all pipes but we have no way to tell whether an fd is a pipe or
not.
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that could cause clearing of fd-bits past allocated bit-vectors.
Bug introduced on master by
988f5f5e8061ce2e135a314ca782788eda478a06
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Currently (OpenBSD 6.2) the kqueu implementation on
opnebsd does not work properly for EOF conditions when
using EV_DISPATCH, so we use the EV_ONESHOT fallback there.
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kqueue is broken on earlier versions of OS X.
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by having different structs with same name.
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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
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The implementation is still hidden behind ERTS_ENABLE_LOCK_COUNT, and
all categories are still enabled by default, but the actual counting can be
toggled at will.
OTP-13170
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Improve accuracy of timeouts using a premature timeout then
return to sleep with a shorter timeout just before requested
timeout. This approach is only used on certain platforms where
we know it improves the accuracy of the timeouts, e.g. MacOS X.
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Microstate accounting is a way to track which state the
different threads within ERTS are in. The main usage area
is to pin point performance bottlenecks by checking which
states the threads are in and then from there figuring out
why and where to optimize.
Since checking whether microstate accounting is on or off is
relatively expensive if done in a short loop only a few of the
states are enabled by default and more states can be enabled
through configure.
I've done some benchmarking and the overhead with it turned off
is not noticible and with it on it is a fraction of a percent.
If you enable the extra states, depending on the benchmark,
the ovehead when turned off is about 1% and when turned on
somewhere inbetween 5-15%.
OTP-12345
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Conflicts:
OTP_VERSION
erts/doc/src/notes.xml
erts/vsn.mk
otp_versions.table
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* sverk/poll-lost-wakeup/OTP-12859:
erts: Fix race in poller thread wake up
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OTP-12845
* bruce/change-license:
fix errors caused by changed line numbers
Change license text to APLv2
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to have one common implementation for both _kp and _nkp.
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* egil/erts/high_accuracy_sleep/OTP-12236:
erts: Add high accuracy poll timeouts
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Different poll/select implementations have different ways
to handle timeouts of < ms accuracy. Most have extended
API like pselect or such, while others rely on using
timerfds (epoll_wait). If no high accuracy timeout is
available, we simply round up to nearest ms. If we do not
roundup we will spin the last ms when waiting for a timeout
which is not desirable.
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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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The warning is:
sys/common/erl_poll.c:2513:72: warning: for loop has empty body [-Wempty-body]
for (prev_ps = pollsets; ps != prev_ps->next; prev_ps = prev_ps->next);
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Make sure the fd-sets (read and write) are of equal size.
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An attempt to beautify the code by reducing the amount of #ifdef's
in the hot code path.
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This allows erl_poll to select() on file descriptors greater than
FD_SETSIZE (1024) on Darwin. The fd sets are manually (re)allocated and
freed.
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Conflicts:
lib/diameter/autoconf/vxworks/sed.general
xcomp/README.md
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I/O events could potentially be delayed for ever when enabling
kernel-poll on a non-SMP runtime system executing on Solaris. When
also combined with async-threads the runtime system hung before
completing the boot phase. This bug was introduced in
erts-5.9/OTP-R15B.
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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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