From: Ferruh Yigit <ferruh.yigit@xilinx.com>
To: Joyce Kong <joyce.kong@arm.com>, Jakub Grajciar <jgrajcia@cisco.com>
Cc: <ruifeng.wang@arm.com>, <dev@dpdk.org>, <nd@arm.com>
Subject: Re: [PATCH v1 1/2] net/memif: add a Rx fast path
Date: Wed, 18 May 2022 18:06:01 +0100 [thread overview]
Message-ID: <03c405ad-eb23-5f8a-782c-5f80bc9bf96d@xilinx.com> (raw)
In-Reply-To: <20220517105109.1086090-2-joyce.kong@arm.com>
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.kong@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
next prev parent reply other threads:[~2022-05-18 17:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-12 9:32 [RFC] net/memif: add a fast path for Rx Joyce Kong
2022-05-17 10:51 ` [PATCH v1 0/2] add a fast path for memif Rx/Tx Joyce Kong
2022-05-17 10:51 ` [PATCH v1 1/2] net/memif: add a Rx fast path Joyce Kong
2022-05-18 16:53 ` Ferruh Yigit
2022-05-19 7:00 ` Joyce Kong
2022-05-19 8:44 ` Joyce Kong
2022-05-18 17:06 ` Ferruh Yigit [this message]
2022-05-19 15:09 ` Joyce Kong
2022-05-19 16:38 ` Ferruh Yigit
2022-05-17 10:51 ` [PATCH v1 2/2] net/memif: add a Tx " Joyce Kong
2022-05-17 13:59 ` [PATCH v1 0/2] add a fast path for memif Rx/Tx Morten Brørup
2022-05-18 2:48 ` Ruifeng Wang
2022-07-01 10:28 ` [PATCH v2 " Joyce Kong
2022-07-01 10:28 ` [PATCH v2 1/2] net/memif: add a Rx fast path Joyce Kong
2022-07-01 16:51 ` Stephen Hemminger
2022-08-22 3:47 ` [PATCH v3 0/2] add a fast path for memif Rx/Tx Joyce Kong
2022-08-22 3:47 ` [PATCH v3 1/2] net/memif: add a Rx fast path Joyce Kong
2022-08-31 16:25 ` Stephen Hemminger
2022-09-07 6:06 ` Joyce Kong
2022-08-22 3:47 ` [PATCH v3 2/2] net/memif: add a Tx " Joyce Kong
2022-07-01 10:28 ` [PATCH v2 " Joyce Kong
2022-09-15 6:58 ` [PATCH v4 0/2] add a fast path for memif Rx/Tx Joyce Kong
2022-09-15 6:58 ` [PATCH v4 1/2] net/memif: add a Rx fast path Joyce Kong
2022-09-15 6:58 ` [PATCH v4 2/2] net/memif: add a Tx " Joyce Kong
2022-09-22 9:12 ` [PATCH v4 0/2] add a fast path for memif Rx/Tx Ferruh Yigit
2022-12-09 13:59 ` Ferruh Yigit
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