Re: [RFC] traceevent/block: Add REQ_ATOMIC flag to block trace events

[Jens Axboe <axboe@kernel.dk>]

On 5/21/25 11:15 PM, Ritesh Harjani (IBM) wrote:
> Ritesh Harjani (IBM) <ritesh.list@gmail.com> writes:
> 
>> John Garry <john.g.garry@oracle.com> writes:
>>
>>> On 03/04/2025 06:28, Ritesh Harjani (IBM) wrote:
>>>> Filesystems like XFS can implement atomic write I/O using either REQ_ATOMIC
>>>> flag set in the bio or via CoW operation. It will be useful if we have a
>>>> flag in trace events to distinguish between the two. 
>>>
>>> I suppose that this could be useful. So far I test with block driver 
>>> traces, i.e. NVMe or SCSI internal traces, just to ensure that we see 
>>> the requests sent as expected
>>>
>>
>> Right.
>>
>>> This patch adds
>>>> char 'a' to rwbs field of the trace events if REQ_ATOMIC flag is set in
>>>> the bio.
>>>
>>> All others use uppercase characters, so I suggest that you continue to 
>>> use that.
>>
>> It will be good to know on whether only uppercase characters are allowed
>> or we are good with smallcase characters too? 
>>
>>> Since 'A' is already used, how about 'U' for untorn? Or 'T' 
>>> for aTOMic :)
>>>
>>
>> If 'a' is not allowed, then we can change it to 'T' maybe.
>>
> 
> Gentle ping on this.. Any comments/feedback?
> 
> It will be good to have these trace events with an identifier to
> differentiate between reqs/bios submitted with REQ_ATOMIC flag.

Just send a v2 with the modified changed. I think 'U' is the most
appropriate one.

-- 
Jens Axboe