kmalloc allocates physically contiguous memory, while vmalloc allocates memory which is only virtually contiguous and not necessarily physically contiguous. Usually physically contiguous memory is required for hardware devices (dma etc) , thus kmalloc is useful for allocating such memory. And though this is not always the requirement, still kmalloc is preferred , because it is better in terms of performance, because vmalloc can result in greater TLB thrashing . vmalloc is useful when very large amounts of memory is to be allocated, because when memory becomes heavily fragmented, you may not get success while allocating large memory via kmalloc. Slab layer serves like a cache for commonly used data structures, again with a view to reduce fragmentation, and to speed up operations. To allocate objects from slab you will have to use functions like kmem_cache_create() and kmem_cache_alloc() .. thanks Vivek On Thu, Nov 22, 2012 at 8:42 AM, horse_rivers <horse_rivers@xxxxxxx> wrote: > > thanks! > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
