malloc_info() 是如何工作的？

发布于 2024-09-26 21:29:23 字数 1703 浏览 5 评论 0原文

我一直在试图弄清楚位于 malloc.h 中的 malloc_info() 函数是如何工作的。我知道你必须向它传递一个 FILE* 并且尚未实现任何选项，但我不知道它实际报告的内容！？此外，我编写了一个测试应用程序，它分配一大堆内存，并且从 malloc_info() 报告的值不会改变，除非我进行了 20,000 1 字节分配？

有没有人对 malloc_info() 有任何经验，并且可以阐明它应该测量内存的哪些方面？

应该指出的是，我在谷歌上几乎找不到任何关于 malloc_info() 的信息，只有一些粗略的错误报告。

malloc_info() 的示例输出：

<malloc version="1">
    <heap nr="0">
        <sizes>
        </sizes>
        <total type="fast" count="0" size="0"/>
        <total type="rest" count="0" size="0"/>
        <system type="current" size="135168"/>
        <system type="max" size="135168"/>
        <aspace type="total" size="135168"/>
        <aspace type="mprotect" size="135168"/>
    </heap>
    <total type="fast" count="0" size="0"/>
    <total type="rest" count="0" size="0"/>
    <system type="current" size="135168"/>
    <system type="max" size="135168"/>
    <aspace type="total" size="135168"/>
    <aspace type="mprotect" size="135168"/>
</malloc>

编辑：

作为进一步的解释；我的后备位置是 mallinfo() 函数，但我希望使用 malloc_info() ，因为据我所知，它的目标是替换 mallinfo() 。我发现 mallinfo() 和 malloc_info() 的工作方式不同。在我的测试中， mallinfo() 跟踪我的所有分配，而 malloc_info() 根本无法做到这一点。我只能假设 malloc_info() 当前已损坏，或者它不具有与 mallinfo() 相同的用途。

在omnifarious 给出的文章中，有充分的理由表明应弃用 mallinfo()：

它完全不适合64位机器。数据类型 SysV 规范要求不允许对于大于 2^31 字节的值（全部结构中的字段是整数）。这第二个问题是数据结构确实是特定于 malloc 实现 SysV 用于那个时候。

不过我认为此时 malloc_info() 还没有准备好取代它。

进一步编辑：经过更多挖掘后，似乎 malloc_info() 在 135168 出现的所有位置（至少是它对应的位置）报告了 mallinfo() 的竞技场大小。与 mallinfo() 所允许的相比，这似乎没那么有用，并且是一个非常一维的信息。

原文

I've been trying to figure out how the malloc_info() function located in malloc.h works. I know you have to pass it a FILE* and that no options are implemented yet, but I am at a loss as to what it is actually reporting!? Furthermore i've written a test app that allocates a whole bunch of memory and the values reported from malloc_info() don't change, except when I did 20,000 1 byte allocations?

Is there anyone out there who has any experience with malloc_info() and can shed some light on what aspects of memory it is supposed to measure?

It should be noted that I could find next to nothing on google about malloc_info(), just some sketchy bug reports.

Example Output from malloc_info():

<malloc version="1">
    <heap nr="0">
        <sizes>
        </sizes>
        <total type="fast" count="0" size="0"/>
        <total type="rest" count="0" size="0"/>
        <system type="current" size="135168"/>
        <system type="max" size="135168"/>
        <aspace type="total" size="135168"/>
        <aspace type="mprotect" size="135168"/>
    </heap>
    <total type="fast" count="0" size="0"/>
    <total type="rest" count="0" size="0"/>
    <system type="current" size="135168"/>
    <system type="max" size="135168"/>
    <aspace type="total" size="135168"/>
    <aspace type="mprotect" size="135168"/>
</malloc>

EDIT:

As a further explanation; my fallback position is the mallinfo() function, but I was hoping to use malloc_info() as from what I can gather it is targeted to replace mallinfo(). What I've found is that mallinfo() and malloc_info() do not work the same. In my tests mallinfo() tracks all my allocations while malloc_info() fails to do so at all. I can only assume that malloc_info() is currently broken, or it is not intended to serve the same purpose as mallinfo().

In the article given by omnifarious there are good reasons that mallinfo() should be deprecated:

it is completely unsuitable for 64-bit machines. The data types
required by the SysV spec don’t allow
for values larger 2^31 bytes (all
fields in the structure are ints). The
second problem is that the data
structure is really specific to the
malloc implementation SysV used at
that time.

However I think that at this time malloc_info() is not yet ready to take it's place.

FURTHER EDIT:
After a bit more digging it seems that malloc_info() is reporting the arena size from mallinfo() in all places where 135168 appears (at least that's what it corresponds to). This seems much less useful and is a very one dimensional piece of information compared with what mallinfo() allows for.

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