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How do cache lines work?
... a rule of thumb, if the processor can't forecast a memory access (and prefetch it), the retrieval process can take ~90 nanoseconds, or ~250 clock cycles (from the CPU knowing the address to the CPU receiving data).
By contrast, a hit in L1 cache has a load-use latency of 3 or 4 cycles, and a store...
How to determine whether a given Linux is 32 bit or 64 bit?
...et your specific machine hardware name run
uname -m
You can also call
getconf LONG_BIT
which returns either 32 or 64
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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...
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...
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
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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...
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...
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...
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...