Hi ,

Does any one know what the default memory allocator is on linux -Is it different for each distro ?



Thanks in advance

Please clarify your qn. Do you mean how to allocate memory in eg C ( malloc() ) or which kernel service allocates memory to processes?

Sorry I meant to say kernel memmory .

In Solaris the memory allocator that's used is libumem which is preloaded .
Is there an equivalent for linux ?

I would say SLAB and SLUB are what you are looking for. You may check on lwn.net for more information if you like.

I am using Redhat 4.5 distro and gcc3.4.6 is the compiler - I don't think this allocator will work for this version of Linux .

hu? SLAB has been there since the 2.4 series at least and was designed around 1994, is it not old enough? What kernel are you using? I probably just did not understand your question, sorry.

As you can see from reading the kernel source, there have been several memory-allocator schemes used in different generations of the kernel. The most-recent one is based on "slabs," which takes full advantage of the fact that kernel memory-allocations usually ask for and release memory blocks of only a few well-known sizes. In other words, if you know that (among other things) you're constantly allocating and releasing blocks of (say...) 148 bytes, it's a very good idea to set-aside a larger chunk of memory (a "slab") just for allocations of that size.

In this way, a particular "slab" basically won't fragment. You don't have to waste a lot of time joining adjacent blocks together. The tradeoff is that you "waste" memory... but these days, "frankly, who cares?" (Memory we got, but microseconds are as precious as ever.)

the version of the kernel is 2.6.9-55.EL