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d65d2fb6b5
Before this patch, the MN scheduler waits for the IO with the
following steps:
1. `poll(fd, timeout=0)` to check fd is ready or not.
2. if fd is not ready, waits with MN thread scheduler
3. call `func` to issue the blocking I/O call
The advantage of advanced `poll()` is we can wait for the
IO ready for any fds. However `poll()` becomes overhead
for already ready fds.
This patch changes the steps like:
1. call `func` to issue the blocking I/O call
2. if the `func` returns `EWOULDBLOCK` the fd is `O_NONBLOCK`
and we need to wait for fd is ready so that waits with MN
thread scheduler.
In this case, we can wait only for `O_NONBLOCK` fds. Otherwise
it waits with blocking operations such as `read()` system call.
However we don't need to call `poll()` to check fd is ready
in advance.
With this patch we can observe performance improvement
on microbenchmark which repeats blocking I/O (not
`O_NONBLOCK` fd) with and without MN thread scheduler.
```ruby
require 'benchmark'
f = open('/dev/null', 'w')
f.sync = true
TN = 1
N = 1_000_000 / TN
Benchmark.bm{|x|
x.report{
TN.times.map{
Thread.new{
N.times{f.print '.'}
}
}.each(&:join)
}
}
__END__
TN = 1
user system total real
ruby32 0.393966 0.101122 0.495088 ( 0.495235)
ruby33 0.493963 0.089521 0.583484 ( 0.584091)
ruby33+MN 0.639333 0.200843 0.840176 ( 0.840291) <- Slow
this+MN 0.512231 0.099091 0.611322 ( 0.611074) <- Good
```
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| .. | ||
| array.h | ||
| basic_operators.h | ||
| bignum.h | ||
| bits.h | ||
| class.h | ||
| cmdlineopt.h | ||
| compar.h | ||
| compile.h | ||
| compilers.h | ||
| complex.h | ||
| cont.h | ||
| dir.h | ||
| enc.h | ||
| encoding.h | ||
| enum.h | ||
| enumerator.h | ||
| error.h | ||
| eval.h | ||
| file.h | ||
| fixnum.h | ||
| gc.h | ||
| hash.h | ||
| imemo.h | ||
| inits.h | ||
| io.h | ||
| load.h | ||
| loadpath.h | ||
| math.h | ||
| missing.h | ||
| numeric.h | ||
| object.h | ||
| parse.h | ||
| proc.h | ||
| process.h | ||
| ractor.h | ||
| random.h | ||
| range.h | ||
| rational.h | ||
| re.h | ||
| ruby_parser.h | ||
| sanitizers.h | ||
| serial.h | ||
| signal.h | ||
| st.h | ||
| static_assert.h | ||
| string.h | ||
| struct.h | ||
| symbol.h | ||
| thread.h | ||
| time.h | ||
| transcode.h | ||
| util.h | ||
| variable.h | ||
| vm.h | ||
| warnings.h | ||