On Mon, Aug 29, 2005 at 12:03:51PM +0530, Gaurav Dhiman wrote: > Just wanted to know, is it a good idea to kmalloc for a small > structure. For example if I define a structure in kernel of 10 bytes, > and I want to get the memory allocated dynamically for it N number of > times, is it good to kmalloc for it every time. Depends on how many times you need to allocate such a structure. > As kmalloc() allocates the memory in terms of page size (4k), atleast > 4K will be allocated for each kmalloc() call in above case. On other > side, wont it be good idea to get one page allocated with kmalloc() > and then use it to store an array of our 10 byte structure and if we > need more we can get one more page allocated with kmalloc(). In this > way we can have list of kmalloc'ed pages and each page represents the > array of out 10 byte strucutre. kmalloc() will use the slab allocator, 10 byte structures will go into the "size-32" slab, so only 22 bytes are wasted. > I am asking this as I am adopting the second approch (list of > kmalloc'ed pages) in one of my kernel modules, just wanted to know is > it worth doing so much of list maintaince of kmalloc'ed pages or we > can simply use the kmalloc for allocating memory to each structure. Don't try to reinvent the wheel, there already is such a way to allocate memory. Use the slab allocator, see kmem_cache_create() and kmem_cache_alloc() in mm/slab.c. Erik -- Erik Mouw J.A.K.Mouw@xxxxxxxxxxxxxx mouw@xxxxxxxxxxxx
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