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此言差矣，sgi stl对小于128字节的小内存是有很高效的内存池算法的。
malloc 的效率低是公认了的 ...
ydfgic 发表于 2011-08-26 13:09 ![]()
malloc 的效率是谁公认低了？
sgi stl 内存池自然有其优点， 但毛病也不小
1。 无法处理大块内存申请吧， 如果处理大块内存申请， 要么内存块的跨度必须大， 就是浪费内存； 要么要求链表数量足够多， 如果链表数量足够多， 循环又要多了（分配2， 结果该链表没有， 去4的里面找， 也没有， 去6的链表找， 再没有。。。。）
2。 无法内存回收吧， 除非它再加上buddy 系统， 可是至少sgi stl 没有； 它就是一个动态平衡算法， 适应的峰值不高的应用， 如果一瞬间要求2G的内存， 然后剩下的1个月， 只要求1M的内存， 它的表现不咋地
* Why use this malloc?
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This is not the fastest, most space-conserving, most portable, or
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most tunable malloc ever written. However it is among the fastest
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while also being among the most space-conserving, portable and tunable.
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Consistent balance across these factors results in a good general-purpose
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allocator for malloc-intensive programs.
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The main properties of the algorithms are:
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* For large (>= 512 bytes) requests, it is a pure best-fit allocator,
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with ties normally decided via FIFO (i.e. least recently used).
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* For small (<= 64 bytes by default) requests, it is a caching
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allocator, that maintains pools of quickly recycled chunks. 这个是不是sgi stl 的基本手法？？？
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* In between, and for combinations of large and small requests, it does
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the best it can trying to meet both goals at once.
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* For very large requests (>= 128KB by default), it relies on system
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memory mapping facilities, if supported.
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发表于 2011-08-25 21:06
