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bpftrace教程【官方】 - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
...见bpftrace完整参考。
该教程贡献者是Brendan Gregg, Netflix (2018), 基于他的DTrace教程系列 DTrace Tutorial。
1. 列出所有探针
bpftrace -l 'tracepoint:syscalls:sys_enter_*'
"bpftrace -l" 列出所有探测点，并且可以添加搜索项。
探针是用于捕...
Is there a performance gain in using single quotes vs double quotes in ruby?
...
$ ruby -v
ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-darwin11.0.0]
$ cat benchmark_quotes.rb
# As of Ruby 1.9 Benchmark must be required
require 'benchmark'
n = 1000000
Benchmark.bm(15) do |x|
x.report("assign single") { n.times do; c =...
What is the difference between ~> and >= when specifying rubygem in Gemfile?
... version provided and use that until it reaches a maximum version. So ~>0.8.5 is semantically equivalent to:
gem "cucumber", ">=0.8.5", "<0.9.0"
The easy way to think about it is that you're okay with the last digit incrementing to some arbitrary value, but the ones preceding it in the st...
C# Thread safe fast(est) counter
...
answered Nov 1 '12 at 16:50
Austin SalonenAustin Salonen
44.8k1515 gold badges100100 silver badges134134 bronze badges
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Command-line Unix ASCII-based charting / plotting tool
... + *+ * + * * + sin(x) ****** +
0.8 ++ * * * * * * ++
| * * * * * * |
0.6 ++ * * * * * *...
How to get first character of string?
...
1080
What you want is charAt.
var x = 'some string';
alert(x.charAt(0)); // alerts 's'
...
What does (x ^ 0x1) != 0 mean?
...
The XOR operation (x ^ 0x1) inverts bit 0. So the expression effectively means: if bit 0 of x is 0, or any other bit of x is 1, then the expression is true.
Conversely the expression is false if x == 1.
So the test is the same as:
if (x != 1)
...
how to set “camera position” for 3d plots using python/matplotlib?
...w my plot. I then adjusted the azimuth angle, or azim, to vary the full 360deg around my plot, saving the figure at each instance (and noting which azimuth angle as I saved the plot). For a more complicated camera pan, you can adjust both the elevation and angle to achieve the desired effect.
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Is there a standard sign function (signum, sgn) in C/C++?
...+ version yet:
template <typename T> int sgn(T val) {
return (T(0) < val) - (val < T(0));
}
Benefits:
Actually implements signum (-1, 0, or 1). Implementations here using copysign only return -1 or 1, which is not signum. Also, some implementations here are returning a float (or...
How to split a column into two columns?
...er way, but this here's one approach:
row
0 00000 UNITED STATES
1 01000 ALABAMA
2 01001 Autauga County, AL
3 01003 Baldwin County, AL
4 01005 Barbour County, AL
df = pd.DataFrame(df.row.str.split(' ',1).tolist(),
...