On 5/17/2022 11:51 AM, Joyce Kong wrote:
For memif non-zero-copy mode, there is a branch to compare
the mbuf and memif buffer size during memory copying. Add
a fast memory copy path by removing this branch with mbuf
and memif buffer size defined at compile time. The removal
of the branch leads to considerable performance uplift.
When memif <= buffer size, Rx chooses the fast memcpy path,
otherwise it would choose the original path.
Test with 1p1q on Ampere Altra AArch64 server,
--------------------------------------------
buf size | memif <= mbuf | memif > mbuf |
--------------------------------------------
non-zc gain | 4.30% | -0.52% |
--------------------------------------------
zc gain | 2.46% | 0.70% |
--------------------------------------------
Test with 1p1q on Cascade Lake Xeon X86server,
-------------------------------------------
buf size | memif <= mbuf | memif > mbuf |
-------------------------------------------
non-zc gain | 2.13% | -1.40% |
-------------------------------------------
zc gain | 0.18% | 0.48% |
-------------------------------------------
Signed-off-by: Joyce Kong <joyce.k...@arm.com>
<...>
+ } else {
+ while (n_slots && n_rx_pkts < nb_pkts) {
+ mbuf_head = rte_pktmbuf_alloc(mq->mempool);
+ if (unlikely(mbuf_head == NULL))
+ goto no_free_bufs;
+ mbuf = mbuf_head;
+ mbuf->port = mq->in_port;
+
+next_slot2:
+ s0 = cur_slot & mask;
+ d0 = &ring->desc[s0];
- rte_memcpy(rte_pktmbuf_mtod_offset(mbuf, void *,
- dst_off),
- (uint8_t *)memif_get_buffer(proc_private, d0) +
- src_off, cp_len);
+ src_len = d0->length;
+ dst_off = 0;
+ src_off = 0;
Hi Joyce, Jakub,
Something doesn't look right in the original code (not in this patch),
can you please help me check if I am missing something?
For the memif buffer segmented case, first buffer will be copied to
mbuf, 'dst_off' increased and jump back to process next memif segment:
+ d0
|
v
+++ +-+
|a+->+b|
+-+ +-+
+---+
|a |
+-+-+
^
|
+ dst_off
"
if (d0->flags & MEMIF_DESC_FLAG_NEXT)
goto next_slot;
"
But here 'dst_off' set back to '0', wont this cause next memif buffer
segment to write to beginning of mbuf overwriting previous data?
Thanks,
ferruh
