Hi! On 21:16 Fri 09 Sep , Zheng Da wrote:
Hello,
I need to allocate fairly a large piece of memory, about 128KB or 256KB. I tried to use kmalloc, and it sometimes fails, but vmalloc in this case usually still work. But I'm not sure how costly vmalloc is. As far as I know, vmalloc needs to change the page table, and thus might need to invalidate TLB. It seems quite expensive. If it is, maybe I can allocate memory with kmalloc first, and then try to use vmalloc if kmalloc fails. Any suggestions?
If it is at all possible, I would suggest avoiding to allocate more than PAGE_SIZE (usually 4KB) in one continuous chunk. You can use e.g. scatterlists (which are basically lists of pointers) if you need a bigger buffer. -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com