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[v3,0/2] cxl: Region bandwidth calculation for targets with shared upstream link

Message ID 20240529214357.1193417-1-dave.jiang@intel.com (mailing list archive)
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Series cxl: Region bandwidth calculation for targets with shared upstream link | expand

Message

Dave Jiang May 29, 2024, 9:38 p.m. UTC
This series provides recalculation of the CXL region bandwidth when the targets have
shared upstream link by walking the toplogy from bottom up and clamp the bandwdith
as the code trasverses up the tree. An example topology:

 An example topology from Jonathan:

                 CFMWS 0
                   |
          _________|_________
         |                   |
   GP0/HB0/ACPI0017-0  GP1/HB1/ACPI0017-1
     |          |        |           |
    RP0        RP1      RP2         RP3
     |          |        |           |
   SW 0       SW 1     SW 2        SW 3
   |   |      |   |    |   |       |   |
  EP0 EP1    EP2 EP3  EP4  EP5    EP6 EP7

 Computation for the example topology:

 Min (GP0 to CPU BW,
      Min(SW 0 Upstream Link to RP0 BW,
          Min(SW0SSLBIS for SW0DSP0 (EP0), EP0 DSLBIS, EP0 Upstream Link) +
          Min(SW0SSLBIS for SW0DSP1 (EP1), EP1 DSLBIS, EP1 Upstream link)) +
      Min(SW 1 Upstream Link to RP1 BW,
          Min(SW1SSLBIS for SW1DSP0 (EP2), EP2 DSLBIS, EP2 Upstream Link) +
          Min(SW1SSLBIS for SW1DSP1 (EP3), EP3 DSLBIS, EP3 Upstream link))) +
 Min (GP1 to CPU BW,
      Min(SW 2 Upstream Link to RP2 BW,
          Min(SW2SSLBIS for SW2DSP0 (EP4), EP4 DSLBIS, EP4 Upstream Link) +
          Min(SW2SSLBIS for SW2DSP1 (EP5), EP5 DSLBIS, EP5 Upstream link)) +
      Min(SW 3 Upstream Link to RP3 BW,
          Min(SW3SSLBIS for SW3DSP0 (EP6), EP6 DSLBIS, EP6 Upstream Link) +
          Min(SW3SSLBIS for SW3DSP1 (EP7), EP7 DSLBIS, EP7 Upstream link))))

Comments

Alison Schofield June 5, 2024, 6:38 p.m. UTC | #1
On Wed, May 29, 2024 at 02:38:56PM -0700, Dave Jiang wrote:
> This series provides recalculation of the CXL region bandwidth when the targets have
> shared upstream link by walking the toplogy from bottom up and clamp the bandwdith
> as the code trasverses up the tree. An example topology:
> 
>  An example topology from Jonathan:
> 
>                  CFMWS 0
>                    |
>           _________|_________
>          |                   |
>    GP0/HB0/ACPI0017-0  GP1/HB1/ACPI0017-1
>      |          |        |           |
>     RP0        RP1      RP2         RP3
>      |          |        |           |
>    SW 0       SW 1     SW 2        SW 3
>    |   |      |   |    |   |       |   |
>   EP0 EP1    EP2 EP3  EP4  EP5    EP6 EP7

Are the ACPI0017 labels a typo?
Expected host bridges to be labelled as ACPI0016's.

That's all, just did a drive-by on the art today.

-- Alison
Dave Jiang June 6, 2024, 11:27 p.m. UTC | #2
On 6/5/24 11:38 AM, Alison Schofield wrote:
> On Wed, May 29, 2024 at 02:38:56PM -0700, Dave Jiang wrote:
>> This series provides recalculation of the CXL region bandwidth when the targets have
>> shared upstream link by walking the toplogy from bottom up and clamp the bandwdith
>> as the code trasverses up the tree. An example topology:
>>
>>  An example topology from Jonathan:
>>
>>                  CFMWS 0
>>                    |
>>           _________|_________
>>          |                   |
>>    GP0/HB0/ACPI0017-0  GP1/HB1/ACPI0017-1
>>      |          |        |           |
>>     RP0        RP1      RP2         RP3
>>      |          |        |           |
>>    SW 0       SW 1     SW 2        SW 3
>>    |   |      |   |    |   |       |   |
>>   EP0 EP1    EP2 EP3  EP4  EP5    EP6 EP7
> 
> Are the ACPI0017 labels a typo?
> Expected host bridges to be labelled as ACPI0016's.
> 
> That's all, just did a drive-by on the art today.

It would be something like below in this case:
        GP0/ACPI0017-0
        HB0/ACPI0016-0
           |     |
          RP0   RP1

or

        GP0/ACPI0017-0
HB0/ACPI0016-0  HB1/ACPI0016-1
      |               |
     RP0             RP1




> 
> -- Alison
Dave Jiang June 6, 2024, 11:46 p.m. UTC | #3
On 6/6/24 4:27 PM, Dave Jiang wrote:
> 
> 
> On 6/5/24 11:38 AM, Alison Schofield wrote:
>> On Wed, May 29, 2024 at 02:38:56PM -0700, Dave Jiang wrote:
>>> This series provides recalculation of the CXL region bandwidth when the targets have
>>> shared upstream link by walking the toplogy from bottom up and clamp the bandwdith
>>> as the code trasverses up the tree. An example topology:
>>>
>>>  An example topology from Jonathan:
>>>
>>>                  CFMWS 0
>>>                    |
>>>           _________|_________
>>>          |                   |
>>>    GP0/HB0/ACPI0017-0  GP1/HB1/ACPI0017-1
>>>      |          |        |           |
>>>     RP0        RP1      RP2         RP3
>>>      |          |        |           |
>>>    SW 0       SW 1     SW 2        SW 3
>>>    |   |      |   |    |   |       |   |
>>>   EP0 EP1    EP2 EP3  EP4  EP5    EP6 EP7
>>
>> Are the ACPI0017 labels a typo?
>> Expected host bridges to be labelled as ACPI0016's.
>>
>> That's all, just did a drive-by on the art today.
> 
> It would be something like below in this case:
>         GP0/ACPI0017-0
>         HB0/ACPI0016-0
>            |     |
>           RP0   RP1

Actually it should be:
	ACPI0017-0
    HB0/GP0/ACPI0016-0
	|	|
       RP0     RP1

Generic Port is identified by device handle that is off of ACPI0016 HID. 

> 
> or
> 
>         GP0/ACPI0017-0
> HB0/ACPI0016-0  HB1/ACPI0016-1
>       |               |
>      RP0             RP1
> 
> 
> 
> 
>>
>> -- Alison
>