Hi Christoph,
On Fri, Jul 01, 2022 at 04:37:00PM +0200, Christoph Lameter wrote:
> On Fri, 1 Jul 2022, Feng Tang wrote:
>
> > static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
> > - unsigned long addr, struct kmem_cache_cpu *c)
> > + unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size)
> > {
>
> It would be good to avoid expanding the basic slab handling functions for
> kmalloc. Can we restrict the mods to the kmalloc related functions?
Yes, this is the part that concerned me. I tried but haven't figured
a way.
I started implemting it several month ago, and stuck with several
kmalloc APIs in a hacky way like dump_stack() when there is a waste
over 1/4 of the object_size of the kmalloc_caches[][].
Then I found one central API which has all the needed info (object_size &
orig_size) that we can yell about the waste :
static __always_inline void *slab_alloc_node(struct kmem_cache *s, struct list_lru *lru,
gfp_t gfpflags, int node, unsigned long addr, size_t orig_size)
which I thought could be still hacky, as the existing 'alloc_traces'
can't be resued which already has the count/call-stack info. Current
solution leverage it at the cost of adding 'orig_size' parameters, but
I don't know how to pass the 'waste' info through as track/location is
in the lowest level.
Thanks,
Feng
