On Wed, Sep 24, 2014 at 4:41 PM, Keith Busch <keith.busch@xxxxxxxxx> wrote:
> Just poking this thread to make sure it's not dead. :)
>
> I tested Yijing's proposal and it is successful on our Intel server
> platforms; hoping either this or something that derives similar behavior
> will be applied so we can remove bus tuning kernel parameters.
>
> Tested-by: Keith Busch <keith.busch@xxxxxxxxx>
Oops, thanks for poking me, because this was indeed dead.
My main objection was to testing "is_hotplug_bridge". That doesn't
seem right, because this issue really isn't specific to hotplug. I
didn't see a resolution of that, but let me know if I missed it.
Bjorn
> On Thu, 4 Sep 2014, Yijing Wang wrote:
>>>>>>
>>>>>> if (pcie_bus_config == PCIE_BUS_TUNE_OFF) {
>>>>>> + pcie_bus_update_set(dev);
>>>>>
>>>>>
>>>>> You're only adding this to the PCIE_BUS_TUNE_OFF path. Can't the same
>>>>> problem occur for other pcie_bus_config settings?
>>>>
>>>>
>>>> We only found the problem during PCIE_BUS_TUNE_OFF set. Other mode like
>>>> PCIE_BUS_SAFE and PCIE_BUS_PEER2PEER.
>>>> This issue won't happen.
>>>
>>>
>>> Sorry, I can't parse this. Are you saying the problem won't happen in
>>> the other modes? Why not?
>>
>>
>> Hi Bjorn, when in PCIE_BUS_SAFE mode, pcie_find_smpss() will find the
>> largest available mpss in a pcie path.
>> Then call pcie_bus_configure_set() to set all devices' mps to the largest
>> available mps in this path, so
>> all devices in the path will have the same mps. When in
>> PCIE_BUS_PEER2PEER, all devices' mps will be set to 128B
>> for safety. And to the PCIE_BUS_PERFORMANCE mode, I found Jon's comment in
>> pcie_write_mps(),
>>
>> /* For "Performance", the assumption is made that
>> * downstream communication will never be larger
>> than
>> * the MRRS. So, the MPS only needs to be
>> configured
>> * for the upstream communication. This being the
>> case, <------
>> * walk from the top down and set the MPS of the
>> child
>> * to that of the parent bus.
>>
>> So I think the problem won't happen in other modes.
>>
>> Thanks!
>> Yijing.
>>
>>
>>>
>>>>>> pcie_bus_detect_mps(dev);
>>>>>> return 0;
>>>>>> }
>>>
>>>
>>> .
>>>
>>
>>
>> --
>> Thanks!
>> Yijing
>>
>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
