[dpdk-dev] why uses the cldemote here in dpdk21.02?

[dpdk-dev] why uses the cldemote here in dpdk21.02?

[vic_yf]

Hi,
        when I read the  dpdk dlb eventdev driver code, I find that it  used the cldemote instruction in the dlb_recv_qe(). But I don't understand why it used there? 
        The cldemote instruction means to move the cache line to the more remote cache, which helps to  accelerate core-to-core communication. But who will be use the memory of  cache_line_base?



>static __rte_always_inline int dlb_recv_qe(struct dlb_port *qm_port, struct dlb_dequeue_qe *qe, 	    uint8_t *offset) 

>{
> 

>        cq_addr = dlb_port[qm_port->id][PORT_TYPE(qm_port)].cq_base; 

>        cq_addr = &cq_addr[qm_port->cq_idx]; 

>        cache_line_base = (void *)(((uintptr_t)cq_addr) & ~0x3F); 

>        *offset = ((uintptr_t)cq_addr & 0x30) >> 4; 

>        /* Load the next CQ cache line from memory. Pack these reads as tight 

>        * as possible to reduce the chance that DLB invalidates the line while 

>        * the CPU is reading it. Read the cache line backwards to ensure that 

>        * if QE[N] (N > 0) is valid, then QEs[0:N-1] are too. 

>        *
>        * (Valid QEs start at &qe[offset]) 

>        */ 

>        qes[3] = _mm_load_si128((__m128i *)&cache_line_base[6]);
>        qes[2] = _mm_load_si128((__m128i *)&cache_line_base[4]); 

>        qes[1] = _mm_load_si128((__m128i *)&cache_line_base[2]); 

>        qes[0] = _mm_load_si128((__m128i *)&cache_line_base[0]); 

>
>        /* Evict the cache line ASAP */ 

>        rte_cldemote(cache_line_base);


Thanks.