From: "lihuisong (C)" <lihuisong@huawei.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: <dev@dpdk.org>, <thomas@monjalon.net>, <ferruh.yigit@amd.com>,
<andrew.rybchenko@oktetlabs.ru>, <liuyonglong@huawei.com>
Subject: Re: [PATCH v3 0/3] introduce maximum Rx buffer size
Date: Tue, 31 Oct 2023 10:57:45 +0800 [thread overview]
Message-ID: <bf781517-0a0a-f74d-8aa3-ef316767a81f@huawei.com> (raw)
In-Reply-To: <20231030114850.799f2bce@fedora>
在 2023/10/31 2:48, Stephen Hemminger 写道:
> On Mon, 30 Oct 2023 09:25:34 +0800
> "lihuisong (C)" <lihuisong@huawei.com> wrote:
>
>>>
>>>> The "min_rx_bufsize" in struct rte_eth_dev_info stands for the
>>>> minimum Rx buffer size supported by hardware. Actually, some
>>>> engines also have the maximum Rx buffer specification, like, hns3.
>>>>
>>>> If mbuf data room size in mempool is greater then the maximum Rx
>>>> buffer size supported by HW, the data size application used in
>>>> each mbuf is just as much as the maximum Rx buffer size supported
>>>> by HW instead of the whole data room size.
>>>>
>>>> So introduce maximum Rx buffer size which is not enforced just to
>>>> report user to avoid memory waste.
>>> I am not convinced this is really necessary.
>>> Your device will use up to 4K of buffer size, not sure why an
>>> application would want to use much larger than that because it
>>> would be wasting a lot of buffer space (most packets are smaller)
>>> anyway.
>>>
>>> The only case where it might be useful is if application is using
>>> jumbo frames (9K) and the application was not able to handle multi
>>> segment packets.
>> Yeah, it is useful if user want a large packet (like, 6K) is in a
>> mbuf. But, in current layer, user don't know what the maximum buffer
>> size per descriptor supported by HW is.
>>> Not handling multi segment packets in SW is just programmer
>>> laziness.
>> User do decide their implement based on their cases in project.
>> May it be a point for this that user don't want to do memcpy for
>> multi segment packets and just use the first mbuf memory.
>>
>> Now that there is the "min_rx_bufsize" to report in ethdev layer.
>> Anyway, DPDK is indeed the lack of the way to report the maximum Rx
>> buffer size per hw descriptor.
> My concern is that you are creating a special case for one driver.
understand your concern.
> And other drivers probably have similar upper bound.
Yes, they also have similar upper bound.
From the codes, the max buffer size of Most PMDs are 16K and bnxt is
9600Byte.
Do we need to report this size? It's a common feature for all PMDs.
>
> Could the warning be better handled in the driver specific configure
> routine rather than updating the ethdev API. Something like:
>
> if (multi-segment-flag off) {
> if (mtu > driver max buf size) {
> return error;
> } else {
> if (mtu > driver max buf size &&
> mtu < mempool_buf_size(mp)) {
> warn that packet maybe segmented ??
> }
> }
>
>
> .
next prev parent reply other threads:[~2023-10-31 2:57 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-08 4:02 [RFC] ethdev: " Huisong Li
2023-08-11 12:07 ` Andrew Rybchenko
2023-08-15 8:16 ` lihuisong (C)
2023-08-15 11:10 ` [PATCH v1 0/3] " Huisong Li
2023-08-15 11:10 ` [PATCH v1 1/3] ethdev: " Huisong Li
2023-09-28 15:56 ` Ferruh Yigit
2023-10-24 12:21 ` lihuisong (C)
2023-08-15 11:10 ` [PATCH v1 2/3] app/testpmd: add maximum Rx buffer size display Huisong Li
2023-08-15 11:10 ` [PATCH v1 3/3] net/hns3: report maximum buffer size Huisong Li
2023-10-27 4:15 ` [PATCH v2 0/3] introduce maximum Rx " Huisong Li
2023-10-27 4:15 ` [PATCH v2 1/3] ethdev: " Huisong Li
2023-10-27 6:27 ` fengchengwen
2023-10-27 7:40 ` Morten Brørup
2023-10-28 1:23 ` lihuisong (C)
2023-10-27 4:15 ` [PATCH v2 2/3] app/testpmd: add maximum Rx buffer size display Huisong Li
2023-10-27 6:28 ` fengchengwen
2023-10-27 4:15 ` [PATCH v2 3/3] net/hns3: report maximum buffer size Huisong Li
2023-10-27 6:17 ` fengchengwen
2023-10-28 1:48 ` [PATCH v3 0/3] introduce maximum Rx " Huisong Li
2023-10-28 1:48 ` [PATCH v3 1/3] ethdev: " Huisong Li
2023-10-29 15:43 ` Stephen Hemminger
2023-10-30 3:08 ` lihuisong (C)
2023-10-28 1:48 ` [PATCH v3 2/3] app/testpmd: add maximum Rx buffer size display Huisong Li
2023-10-28 1:48 ` [PATCH v3 3/3] net/hns3: report maximum buffer size Huisong Li
2023-10-29 15:48 ` [PATCH v3 0/3] introduce maximum Rx " Stephen Hemminger
2023-10-30 1:25 ` lihuisong (C)
2023-10-30 18:48 ` Stephen Hemminger
2023-10-31 2:57 ` lihuisong (C) [this message]
2023-10-31 7:48 ` Morten Brørup
2023-10-31 15:40 ` Stephen Hemminger
2023-11-01 2:36 ` lihuisong (C)
2023-11-01 16:08 ` Stephen Hemminger
2023-11-02 1:59 ` lihuisong (C)
2023-11-02 16:23 ` Ferruh Yigit
2023-11-02 16:51 ` Morten Brørup
2023-11-02 17:05 ` Ferruh Yigit
2023-11-02 17:12 ` Morten Brørup
2023-11-02 17:35 ` Ferruh Yigit
2023-11-03 2:13 ` lihuisong (C)
2023-11-02 12:16 ` [PATCH v4 " Huisong Li
2023-11-02 12:16 ` [PATCH v4 1/3] ethdev: " Huisong Li
2023-11-02 16:35 ` Ferruh Yigit
2023-11-03 2:21 ` lihuisong (C)
2023-11-03 3:30 ` Ferruh Yigit
2023-11-03 6:27 ` lihuisong (C)
2023-11-02 12:16 ` [PATCH v4 2/3] app/testpmd: add maximum Rx buffer size display Huisong Li
2023-11-02 16:42 ` Ferruh Yigit
2023-11-03 2:39 ` lihuisong (C)
2023-11-03 3:53 ` Ferruh Yigit
2023-11-03 6:37 ` lihuisong (C)
2023-11-02 12:16 ` [PATCH v4 3/3] net/hns3: report maximum buffer size Huisong Li
2023-11-03 10:27 ` [PATCH v5 0/3] introduce maximum Rx " Huisong Li
2023-11-03 10:27 ` [PATCH v5 1/3] ethdev: " Huisong Li
2023-11-03 12:37 ` Ivan Malov
2023-11-03 10:27 ` [PATCH v5 2/3] app/testpmd: add maximum Rx buffer size display Huisong Li
2023-11-03 10:27 ` [PATCH v5 3/3] net/hns3: report maximum buffer size Huisong Li
2023-11-03 11:53 ` [PATCH v5 0/3] introduce maximum Rx " Ferruh Yigit
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