On Tue, 2017-04-18 at 10:34 -0700, Code Soldier1 wrote: > Hi Folks, > > I am sure there is a reason for the current sizes of these structures, > However the reason is not obvious to me. So please help me understand. > > Currently the size of sk_buff on an x86_64 system is 232 bytes -- Why > is that. I expected it to be a multiple of 32/64 as they are the most > common cache lines. Since the alignment calculation will align the > structure with the hw cache line, it seems like we might be wasting > space ? > > skb_shared_info on the other hand is perfectly aligned with a size of 320 > bytes. > > Thanks, >
The alignment is there. Look at skb_init() code, using SLAB_HWCACHE_ALIGN
