From: Andrew Lunn <andrew@lunn.ch>
To: Parthiban.Veerasooran@microchip.com
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, horms@kernel.org, saeedm@nvidia.com,
anthony.l.nguyen@intel.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, corbet@lwn.net,
linux-doc@vger.kernel.org, robh+dt@kernel.org,
krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
devicetree@vger.kernel.org, Horatiu.Vultur@microchip.com,
ruanjinjie@huawei.com, Steen.Hegelund@microchip.com,
vladimir.oltean@nxp.com, UNGLinuxDriver@microchip.com,
Thorsten.Kummermehr@microchip.com, Pier.Beruto@onsemi.com,
Selvamani.Rajagopal@onsemi.com, Nicolas.Ferre@microchip.com,
benjamin.bigler@bernformulastudent.ch
Subject: Re: [PATCH net-next v3 08/12] net: ethernet: oa_tc6: implement transmit path to transfer tx ethernet frames
Date: Tue, 19 Mar 2024 14:19:19 +0100 [thread overview]
Message-ID: <96dd422f-0bf9-411d-8cc2-5755c1e60e27@lunn.ch> (raw)
In-Reply-To: <f9d8a18c-b1fe-450c-a5ca-d91f96793a04@microchip.com>
On Tue, Mar 19, 2024 at 12:54:30PM +0000, Parthiban.Veerasooran@microchip.com wrote:
> Hi Andrew,
>
> On 07/03/24 10:38 pm, Andrew Lunn wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> >> @@ -55,6 +77,14 @@
> >> (OA_TC6_CTRL_MAX_REGISTERS *\
> >> OA_TC6_CTRL_REG_VALUE_SIZE) +\
> >> OA_TC6_CTRL_IGNORED_SIZE)
> >> +#define OA_TC6_CHUNK_PAYLOAD_SIZE 64
> >> +#define OA_TC6_DATA_HEADER_SIZE 4
> >> +#define OA_TC6_CHUNK_SIZE (OA_TC6_DATA_HEADER_SIZE +\
> >> + OA_TC6_CHUNK_PAYLOAD_SIZE)
> >> +#define OA_TC6_TX_SKB_QUEUE_SIZE 100
> >
> > So you keep up to 100 packets in a queue. If use assume typical MTU
> > size packets, that is 1,238,400 bits. At 10Mbps, that is 120ms of
> > traffic. That is quite a lot of latency when a high priority packet is
> > added to the tail of the queue and needs to wait for all the other
> > packets to be sent first.
> >
> > Chunks are 64 bytes. So in practice, you only ever need two
> > packets. You need to be able to fill a chunk with the final part of
> > one packet, and the beginning of the next. So i would try using a much
> > smaller queue size. That will allow Linux queue disciplines to give
> > you the high priority packets first which you send with low latency.
> Thanks for the detailed explanation. If I understand you correctly,
>
> 1. The tx skb queue size (OA_TC6_TX_SKB_QUEUE_SIZE) should be 2 to avoid
> the latency when a high priority packet added.
>
> 2. Need to implement the handling part of the below case,
> In case if one packet ends in a chunk and that chunk still having some
> space left to accommodate some bytes from the next packet if available
> from network layer.
This second part is clearly an optimisation. If you have lots of full
MTU packets, 1514 bytes, they take around 24 chunks. Having the last
chunk only 1/2 full does not waste too much bandwidth. But if you are
carrying lots of small packets, say voice, 130 bytes, the wasted
bandwidth starts to add up. But is there a use case for 10Mbps of
small packets? I doubt it.
So if you don't have the ability to combine two packets into one
chunk, i would do that later. Lets get the basics merged first, it can
be optimised later.
Andrew
next prev parent reply other threads:[~2024-03-19 13:19 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-06 8:50 [PATCH net-next v3 00/12] Add support for OPEN Alliance 10BASE-T1x MACPHY Serial Interface Parthiban Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 01/12] Documentation: networking: add OPEN Alliance 10BASE-T1x MAC-PHY serial interface Parthiban Veerasooran
2024-03-06 13:23 ` Andrew Lunn
2024-03-07 6:29 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 02/12] net: ethernet: oa_tc6: implement register write operation Parthiban Veerasooran
2024-03-06 13:40 ` Andrew Lunn
2024-03-07 6:46 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 03/12] net: ethernet: oa_tc6: implement register read operation Parthiban Veerasooran
2024-03-07 0:19 ` Andrew Lunn
2024-03-07 7:04 ` Parthiban.Veerasooran
2024-03-07 13:22 ` Andrew Lunn
2024-03-08 7:12 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 04/12] net: ethernet: oa_tc6: implement software reset Parthiban Veerasooran
2024-03-07 0:35 ` Andrew Lunn
2024-03-07 7:39 ` Parthiban.Veerasooran
2024-03-07 13:24 ` Andrew Lunn
2024-03-08 8:25 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 05/12] net: ethernet: oa_tc6: implement error interrupts unmasking Parthiban Veerasooran
2024-03-07 0:43 ` Andrew Lunn
2024-03-07 8:28 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 06/12] net: ethernet: oa_tc6: implement internal PHY initialization Parthiban Veerasooran
2024-03-07 1:13 ` Andrew Lunn
2024-03-07 14:41 ` Parthiban.Veerasooran
2024-03-07 16:36 ` Andrew Lunn
2024-03-08 12:05 ` Parthiban.Veerasooran
2024-03-08 13:33 ` Andrew Lunn
2024-03-18 11:01 ` Parthiban.Veerasooran
2024-04-12 10:43 ` Parthiban.Veerasooran
2024-04-15 13:15 ` Andrew Lunn
2024-04-16 11:02 ` Parthiban.Veerasooran
2024-04-16 18:18 ` Andrew Lunn
2024-04-17 8:55 ` Parthiban.Veerasooran
2024-03-21 18:49 ` Selvamani Rajagopal
2024-03-22 5:50 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 07/12] net: ethernet: oa_tc6: enable open alliance tc6 data communication Parthiban Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 08/12] net: ethernet: oa_tc6: implement transmit path to transfer tx ethernet frames Parthiban Veerasooran
2024-03-07 17:08 ` Andrew Lunn
2024-03-19 12:54 ` Parthiban.Veerasooran
2024-03-19 13:19 ` Andrew Lunn [this message]
2024-03-20 10:43 ` Parthiban.Veerasooran
2024-03-21 19:04 ` Selvamani Rajagopal
2024-03-21 19:42 ` Andrew Lunn
2024-03-22 18:31 ` Selvamani Rajagopal
2024-03-06 8:50 ` [PATCH net-next v3 09/12] net: ethernet: oa_tc6: implement receive path to receive rx " Parthiban Veerasooran
2024-03-08 0:14 ` Andrew Lunn
2024-03-19 12:54 ` Parthiban.Veerasooran
2024-03-19 13:20 ` Andrew Lunn
2024-03-20 5:55 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 10/12] net: ethernet: oa_tc6: implement mac-phy interrupt Parthiban Veerasooran
2024-03-06 23:42 ` Woojung.Huh
2024-03-07 10:16 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 11/12] microchip: lan865x: add driver support for Microchip's LAN865X MAC-PHY Parthiban Veerasooran
2024-03-06 23:44 ` Woojung.Huh
2024-03-07 9:13 ` Parthiban.Veerasooran
2024-03-06 8:50 ` [PATCH net-next v3 12/12] dt-bindings: net: add Microchip's LAN865X 10BASE-T1S MACPHY Parthiban Veerasooran
2024-03-06 18:16 ` Conor Dooley
2024-03-06 18:48 ` Andrew Lunn
2024-03-06 19:01 ` Conor Dooley
2024-03-20 8:40 ` Parthiban.Veerasooran
2024-03-20 9:53 ` Krzysztof Kozlowski
2024-03-21 8:38 ` Parthiban.Veerasooran
2024-03-21 8:40 ` Krzysztof Kozlowski
2024-03-21 12:00 ` Parthiban.Veerasooran
2024-03-21 15:34 ` Conor Dooley
2024-03-22 6:25 ` Parthiban.Veerasooran
2024-03-22 7:03 ` Krzysztof Kozlowski
2024-03-22 8:28 ` Parthiban.Veerasooran
2024-03-23 10:24 ` Krzysztof Kozlowski
2024-03-25 7:10 ` Parthiban.Veerasooran
2024-03-25 7:10 ` Parthiban.Veerasooran
2024-03-22 18:08 ` Conor Dooley
2024-03-25 7:12 ` Parthiban.Veerasooran
2024-03-20 8:40 ` Parthiban.Veerasooran
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