Looking at the
sock.h file, I see that the obj_size member occurs in the
/* Memory Pressure */ section:
Code:
struct kmem_cache *slab;
unsigned int obj_size;
int slab_flags;
from which I would assume that size of the object to which the
slab points. (In this context, the dynamically allocated kmem_cache buffer.) I believe that the memory slab is being used for transient storage for FIFO stacks of the various protocol handlers, and storing the size is more efficient then recomputing it every time it's needed.
Look at
mempool.h and
slab.h for details.
Note: I'm
not an expert (or even a user) of this code, and my comments flow only from a brief look at some of it.
