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thanks for all your guys, it's very clear . It's
helpful
Can you also explain when to use alloc_pages ? I wanna know in what
case to
use it in drivers. thanks again .
> as i know,kmalloc is based on kmem_cache_alloc ,so what's
the different?
kmalloc uses the generic slab caches available to any kernel code. so your
module will share slab cache with other components in kernel, but if you
specifically want a better slab cache management dedicated to your module only,
that too for a specific type of objects, use the lower function i.e.
kmem_cache_alloc, it will allocate objects from a dedicated slab cache for your
module objects only, you must create the slab cache by calling kmem_cache_create
before allocating any object. kmem_cache_create takes sizeof your object you
want to create slab of, a name which appears in /proc/slabinfo and flags to
govern behavior of your slab cache.
Rajat
On Fri, Nov 5, 2010 at 1:22 PM, Venkatram Tummala <venkatram867@xxxxxxxxx>
wrote:
On Thu, Nov 4, 2010 at 8:03 PM, kernel.niko < kernel.niko@xxxxxxxxx>
wrote: > hi,everyone, > I'm wandering how to use kmalloc and
kmem_cache_alloc. > as i know,kmalloc is based on kmem_cache_alloc ,so
what's the different?
opposed to allocating memory in units of
pages, in which case you
should use
alloc_pages(..).
kmem_cache_alloc is a part of the slab cache
interface. This is used
for reusing objects in the kernel. Lets take
mm_struct objects as an
example. On a live system, processes come & go.
Every process needs a
mm_struct object. And when a process dies, you can
throw away the
object. Instead of creating & throwing away objects,
slab cache
maintains a cache of objects. When you free an object, instead
of
deallocating it, you give it back to the cache. Next time, if
you
want to create a new object, slab cache gives you one object from
the
slab cache. kmem_cache_alloc is one of the interface functions to
use
the slab cache in the kernel. You might want to read about slab
caches
in detail if you need more information.
Venkatram Tummala
> when to use kmalloc? and
> in what
occasion,kmem_cache_alloc should be used?
>
thanks.
>
> 2010-11-05
>
________________________________
> kernel.niko
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