Re: "ibstat -l" displays CA device list in an unsorted order

[Dennis Dalessandro <dennis.dalessandro@intel.com>]

On 2/27/2020 8:33 AM, Jason Gunthorpe wrote:
> On Thu, Feb 27, 2020 at 09:48:45AM +0200, Haim Boozaglo wrote:
>>
>>
>> On 2/26/2020 7:09 PM, Jason Gunthorpe wrote:
>>> On Wed, Feb 26, 2020 at 03:57:49PM +0200, Leon Romanovsky wrote:
>>>> On Wed, Feb 26, 2020 at 09:43:10AM -0400, Jason Gunthorpe wrote:
>>>>> On Tue, Feb 25, 2020 at 10:25:49AM +0200, Haim Boozaglo wrote:
>>>>>>
>>>>>>
>>>>>> On 2/24/2020 9:41 PM, Jason Gunthorpe wrote:
>>>>>>> On Mon, Feb 24, 2020 at 08:06:56PM +0200, Haim Boozaglo wrote:
>>>>>>>> Hi all,
>>>>>>>>
>>>>>>>> When running "ibstat" or "ibstat -l", the output of CA device list
>>>>>>>> is displayed in an unsorted order.
>>>>>>>>
>>>>>>>> Before pull request #561, ibstat displayed the CA device list sorted in
>>>>>>>> alphabetical order.
>>>>>>>>
>>>>>>>> The problem is that users expect to have the output sorted in alphabetical
>>>>>>>> order and now they get it not as expected (in an unsorted order).
>>>>>>>
>>>>>>> Really? Why? That doesn't look like it should happen, the list is
>>>>>>> constructed out of readdir() which should be sorted?
>>>>>>>
>>>>>>> Do you know where this comes from?
>>>>>>>
>>>>>>> Jason
>>>>>>>
>>>>>>
>>>>>> readdir() gives us struct by struct and doesn't keep on alphabetical order.
>>>>>> Before pull request #561 ibstat have used this API of libibumad:
>>>>>> int umad_get_cas_names(char cas[][UMAD_CA_NAME_LEN], int max)
>>>>>>
>>>>>> This API used this function:
>>>>>> n = scandir(SYS_INFINIBAND, &namelist, NULL, alphasort);
>>>>>>
>>>>>> scandir() can return a sorted CA device list in alphabetical order.
>>>>>
>>>>> Oh what a weird unintended side effect.
>>>>>
>>>>> Resolving it would require adding a sorting pass on a linked
>>>>> list.. Will you try?
>>>>
>>>> Please be aware that once ibstat will be converted to netlink, the order
>>>> will change again.
>>>
>>> This is why I suggest a function to sort the linked list that tools
>>> needing sorted order can call. Then it doesn't matter how we got the list
>>>
>>> Jason
>>>
>>
>> I can just sort the list at the time of insertion of each node.
> 
> I'd rather not have to pay the sorting penalty for all users, it seems
> only a few command line tools need the sort

Should we really go out on limb here and assume it's just a few CLI 
tools? What about all the sysadmin type scripts out there? We aren't 
having a good track record not breaking user space lately.

Is the sorting penalty really going to be that bad? It's not like we 
will have a large number of devices that sorting should really be an 
issue I wouldn't think.

-Denny