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Is volatile expensive?
...functions providing additional functionality like getAndSet, compareAndSet etc., so from a performance point of view using it is just useful if you need the added functionality. But I wonder why you refer to the OS here? The functionality is implemented in CPU opcodes directly. And does this imply t...
How to discover number of *logical* cores on Mac OS X?
...et "error: "hw.ncpu" is an unknown key". There is no cpu related entry in /etc/sysctl.conf as well. Frozen Flame's answer worked.
– TheGT
Oct 5 '16 at 23:39
...
Why does the order of the loops affect performance when iterating over a 2D array?
...2]
x[0][3]
x[1][0] etc...
Meaning that you're hitting them all in order. Now look at the 1st version. You're doing:
x[0][0]
x[1][0]
x[2][0]
...
Volatile vs. Interlocked vs. lock
...it check against a CPU register (e.g. EAX because that was what m_Var was fetched into from the very beginning) instead of issuing another read to the memory location of m_Var (this may be cached - we don't know and don't care and that's the point of cache coherency of x86/x64). All the posts earlie...
Why use sprintf function in PHP?
...NTO `Users` SET `user`='%s',`password`='%s',`realname`='%s';", $username, $passwd_hash, $realname);
This method does of course have other uses, such as when printing output as HTML, etc.
Edit: For security reasons, when using a technique as above you must sanitise all input variables with mysql_r...
What does $$ mean in the shell?
... as root and I create /tmp/yourprogname13395 as a symlink pointing to /etc/passwd -- and you write into it.
This is a bad thing to be doing in a shell script. If you're going to use a temporary file for something, you ought to be using a better language which will at least let you add the "exclusiv...
Optimal number of threads per core
...
If your threads don't do I/O, synchronization, etc., and there's nothing else running, 1 thread per core will get you the best performance. However that very likely not the case. Adding more threads usually helps, but after some point, they cause some performance degradat...
What is a “thread” (really)?
...is loaded in the processor core, the thread is running. The processor is fetching instructions demanded by the thread and updating the thread registers. When a context switch is needed, the processor saves this set of register values into memory and loads a set belonging to a different thread, typ...
Memcached下一站：HandlerSocket！ - 更多技术 - 清泛网 - 专注C/C++及内核技术
...形中让Memcached成为故障的根源：
Memcached数据一致性的问题：当MySQL数据变化后，如果不能及时有效的清理掉过期的数据，就会造成数据不一致。这在强调即时性的Web2.0时代，不可取。
Memcached崩溃后的雪崩效应：作为缓存的Memc...
Benchmarking (python vs. c++ using BLAS) and (numpy)
... (renamed: MKL --> Nehalem MKL, Netlib Blas --> Nehalem Netlib BLAS, etc)
Single threaded performance:
Multi threaded performance (8 threads):
Threads vs Matrix size (Ivy Bridge MKL):
Benchmark Suite
Single threaded performance:
Multi threaded (8 threads) performance:
Conclusi...