From: wangyunjian <wangyunjian@huawei.com>
To: Ferruh Yigit <ferruh.yigit@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "thomas@monjalon.net" <thomas@monjalon.net>,
"gowrishankar.m@linux.vnet.ibm.com"
<gowrishankar.m@linux.vnet.ibm.com>,
dingxiaoxiong <dingxiaoxiong@huawei.com>,
"stable@dpdk.org" <stable@dpdk.org>,
"liucheng (J)" <liucheng11@huawei.com>
Subject: Re: [dpdk-dev] [PATCH v2] kni: fix wrong mbuf alloc count in kni_allocate_mbufs
Date: Tue, 22 Jun 2021 12:32:53 +0000 [thread overview]
Message-ID: <bdeda91831854eac98de25200a31e7de@huawei.com> (raw)
In-Reply-To: <4edb86a1-7629-9cc8-8068-702318234904@intel.com>
> -----Original Message-----
> From: Ferruh Yigit [mailto:ferruh.yigit@intel.com]
> Sent: Tuesday, June 22, 2021 8:28 PM
> To: wangyunjian <wangyunjian@huawei.com>; dev@dpdk.org
> Cc: thomas@monjalon.net; gowrishankar.m@linux.vnet.ibm.com;
> dingxiaoxiong <dingxiaoxiong@huawei.com>; stable@dpdk.org; liucheng (J)
> <liucheng11@huawei.com>
> Subject: Re: [PATCH v2] kni: fix wrong mbuf alloc count in kni_allocate_mbufs
>
> On 6/22/2021 11:57 AM, wangyunjian 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>
>
> What do you think to change patch title to something like:
> kni: fix mbuf allocation for alloc FIFO
OK, I will change patch title later.
Thanks
next prev parent reply other threads:[~2021-06-22 12:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-31 12:09 [dpdk-dev] [PATCH] " wangyunjian
2021-06-18 13:37 ` Ferruh Yigit
2021-06-21 3:27 ` wangyunjian
2021-06-21 11:26 ` Ferruh Yigit
2021-06-22 7:32 ` wangyunjian
2021-06-22 7:43 ` Ferruh Yigit
2021-06-22 10:57 ` [dpdk-dev] [PATCH v2] " wangyunjian
2021-06-22 12:27 ` Ferruh Yigit
2021-06-22 12:32 ` wangyunjian [this message]
2021-06-22 12:44 ` [dpdk-dev] [PATCH v3] kni: fix mbuf allocation for alloc FIFO wangyunjian
2021-06-22 20:46 ` [dpdk-dev] [dpdk-stable] " 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
2021-06-24 7:43 ` Thomas Monjalon
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