Refer: Understanding the Linux® Virtual Memory Manager by Mel Gorman. Ch 8- Slab allocator.
Shailesh Jain On Sun, Jul 25, 2010 at 9:52 AM, Hiren Panchasara <hiren.panchas...@gmail.com> wrote: > Hi Sailesh, > > Can you point me to some good basic documentation where I can learn about > memory, it's alignment, coloring and all ? > > Thanks much and regards. > Hiren > > > > On Jul 25, 2010, at 12:26 AM, shailesh jain <coolworldofsh...@gmail.com> > wrote: > >> Slabs are generally allocated in range from 2^5 to 2^17 or something. >> So even if you ask for 10 bytes you will get object from 2^5 slab i.e >> 32 bytes. Objects allocated from slab are actually L1 CPU cache >> aligned for optimal hardware use (other space is used to coloring.) >> >> I am pretty sure that it has be to 4 or 8 bytes aligned because >> unaligned accesses are expensive and linux won't do that. >> >> >> >> >> Shailesh Jain >> >> >> >> >> >> On Sun, Jul 25, 2010 at 12:15 AM, vichy <vichy....@gmail.com> wrote: >>> hi: >>> >>> 2010/7/25 shailesh jain <coolworldofsh...@gmail.com>: >>>> Nope. kmalloc uses slab allocator underneath it. So, No addresses will >>>> not be 4k aligned. >>>> >>>> If you care about 4k aligned addresses you should use >>>> __get_free_page() rather than kmalloc(). >>>> kmalloc's are used for small allocations - think about wastage of >>>> memory if we try to place 4k alignment >>>> requirements. >>> thanks for your reply. >>> so you mean we will have no idea what the alignment of memory address >>> returned by kmalloc? >>> thank you, >>> vichy >>> >> >> >> >> -- >> Shailesh Jain >> >> -- >> To unsubscribe from this list: send an email with >> "unsubscribe kernelnewbies" to ecar...@nl.linux.org >> Please read the FAQ at http://kernelnewbies.org/FAQ >> > -- Shailesh Jain -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecar...@nl.linux.org Please read the FAQ at http://kernelnewbies.org/FAQ
