From: Ajit Khaparde <ajit.khaparde@broadcom.com>
To: wangyunjian <wangyunjian@huawei.com>
Cc: dpdk-dev <dev@dpdk.org>, Ferruh Yigit <ferruh.yigit@intel.com>,
Thomas Monjalon <thomas@monjalon.net>,
gowrishankar.m@linux.vnet.ibm.com, dingxiaoxiong@huawei.com,
dpdk stable <stable@dpdk.org>, Cheng Liu <liucheng11@huawei.com>
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH v3] kni: fix mbuf allocation for alloc FIFO
Date: Wed, 23 Jun 2021 18:55:59 -0700 [thread overview]
Message-ID: <CACZ4nhtHgmLPa0MBwHS+TO4u1C9153OKQ2khoVUmy7=9hy47AA@mail.gmail.com> (raw)
In-Reply-To: <1624365869-31872-1-git-send-email-wangyunjian@huawei.com>
[-- Attachment #1: Type: text/plain, Size: 2447 bytes --]
On Tue, Jun 22, 2021 at 5:44 AM wangyunjian <wangyunjian@huawei.com> wrote:
>
> From: Yunjian Wang <wangyunjian@huawei.com>
>
> In kni_allocate_mbufs(), we alloc mbuf for alloc_q as this code.
> allocq_free = (kni->alloc_q->read - kni->alloc_q->write - 1) \
> & (MAX_MBUF_BURST_NUM - 1);
> The value of allocq_free maybe zero, for example :
> The ring size is 1024. After init, write = read = 0. Then we fill
> kni->alloc_q to full. At this time, write = 1023, read = 0.
>
> Then the kernel send 32 packets to userspace. At this time, write
> = 1023, read = 32. And then the userspace receive this 32 packets.
> Then fill the kni->alloc_q, (32 - 1023 - 1) & 31 = 0, fill nothing.
> ...
> Then the kernel send 32 packets to userspace. At this time, write
> = 1023, read = 992. And then the userspace receive this 32 packets.
> Then fill the kni->alloc_q, (992 - 1023 - 1) & 31 = 0, fill nothing.
>
> Then the kernel send 32 packets to userspace. The kni->alloc_q only
> has 31 mbufs and will drop one packet.
>
> Absolutely, this is a special scene. Normally, it will fill some
> mbufs everytime, but may not enough for the kernel to use.
>
> In this patch, we always keep the kni->alloc_q to full for the kernel
> to use.
>
> Fixes: 49da4e82cf94 ("kni: allocate no more mbuf than empty slots in queue")
> Cc: stable@dpdk.org
>
> Signed-off-by: Cheng Liu <liucheng11@huawei.com>
> Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
> Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
> ---
> v3:
> update patch title
> v2:
> add fixes tag and update commit log
> ---
> lib/kni/rte_kni.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/kni/rte_kni.c b/lib/kni/rte_kni.c
> index 9dae6a8d7c..eb24b0d0ae 100644
> --- a/lib/kni/rte_kni.c
> +++ b/lib/kni/rte_kni.c
> @@ -677,8 +677,9 @@ kni_allocate_mbufs(struct rte_kni *kni)
> return;
> }
>
> - allocq_free = (kni->alloc_q->read - kni->alloc_q->write - 1)
> - & (MAX_MBUF_BURST_NUM - 1);
> + allocq_free = kni_fifo_free_count(kni->alloc_q);
> + allocq_free = (allocq_free > MAX_MBUF_BURST_NUM) ?
> + MAX_MBUF_BURST_NUM : allocq_free;
> for (i = 0; i < allocq_free; i++) {
> pkts[i] = rte_pktmbuf_alloc(kni->pktmbuf_pool);
> if (unlikely(pkts[i] == NULL)) {
> --
> 2.23.0
>
next prev parent reply other threads:[~2021-06-24 1:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4ebfe0d38b335a437edc9c58368153d005f562ce.1622460655.git.wangyunjian@huawei.com>
2021-06-22 10:57 ` [dpdk-stable] [PATCH v2] kni: fix wrong mbuf alloc count in kni_allocate_mbufs wangyunjian
2021-06-22 12:27 ` Ferruh Yigit
2021-06-22 12:32 ` wangyunjian
2021-06-22 12:44 ` [dpdk-stable] [dpdk-dev] [PATCH v3] kni: fix mbuf allocation for alloc FIFO wangyunjian
2021-06-22 20:46 ` Thomas Monjalon
2021-06-23 12:16 ` wangyunjian
2021-06-23 14:11 ` Ferruh Yigit
2021-06-23 14:41 ` Thomas Monjalon
2021-06-24 1:55 ` Ajit Khaparde [this message]
2021-06-24 7:43 ` Thomas Monjalon
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