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@marian-pritsak marian-pritsak commented Mar 18, 2025

It can be beneficial to support multiple DSCP values for trimmed packets sent out via different ports. For example, trimmed packets sent to hosts will get DSCP 5 whereas trimmed packets sent to uplink/spine will have DSCP 7. It is to allow to the destination NIC to know where congestion happened - on downlinks to servers or in the fabric. Such information can be used for a better decision making on how to react to the state of network.

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kcudnik commented Mar 18, 2025

please provide meaningful description to PR

@tjchadaga tjchadaga added the reviewed PR is discussed in SAI Meeting label Mar 20, 2025
* @brief Dynamic DSCP resolution.
*
* In this mode, a new DSCP for the trimmed packet is resolved from the new TRIM_TC
* set by the application using per-port TC_TO_DSCP mapping
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@bandaru-viswanath bandaru-viswanath Mar 24, 2025

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The saiqosmap.h defines only TC_AND_COLOR_TO_DSCP map, but no TC_TO_DSCP map, as part of the set of valid qos maps. In this case, a color value also need to be supplied if this mechanism is desired. Could you please clarify ?

SAI_QOS_MAP_TYPE_TC_AND_COLOR_TO_DSCP = 0x00000005,

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Color does not need to be supplied. The user can just map all the colors to same DSCP, since the TC is used for trimming.

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Or is it possible that different-colors are mapped to different DSCP values ? Is this a valid configuration ?

@marian-pritsak marian-pritsak force-pushed the trim-tc branch 2 times, most recently from d94f37a to 5123b4e Compare March 24, 2025 22:32
inc/saiswitch.h Outdated
SAI_SWITCH_ATTR_PACKET_TRIM_TC_VALUE,

/**
* @brief Queue mapping mode for a trimmed packet
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Typo: DSCP mapping mode

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Thanks, fixed.

@marian-pritsak marian-pritsak force-pushed the trim-tc branch 3 times, most recently from eb30c0b to a956e66 Compare March 25, 2025 21:22
Signed-off-by: Marian Pritsak <marianp@mellanox.com>
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@bandaru-viswanath could you pls approve the SAI PR, we could merge it.

@tjchadaga tjchadaga requested review from bandaru-viswanath and kcudnik and removed request for bandaru-viswanath April 7, 2025 22:08
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kcudnik commented Apr 8, 2025

Please add description for this change

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@kcudnik Please approve the PR and we could merge.

@tjchadaga tjchadaga merged commit 074e2e8 into opencomputeproject:master Apr 10, 2025
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