Re: [PATCH] Btrfs: Do not use data_alloc_cluster in ssd mode

[Chris Mason <clm@fb.com>]

On 07/24/2017 03:06 PM, Austin S. Hemmelgarn wrote:
> On 2017-07-24 14:53, Chris Mason wrote:
>> On 07/24/2017 02:41 PM, David Sterba wrote:
>>>
>>> would it be ok for you to keep ssd_working as before?
>>>
>>> I'd really like to get this patch merged soon because "do not use ssd
>>> mode for ssd" has started to be the recommended workaround. Once this
>>> sticks, we won't need to have any ssd mode anymore ...
>>
>> Works for me.  I do want to make sure that commits in this area 
>> include the workload they were targeting, how they were measured and 
>> what impacts they had.  That way when we go back to try and change 
>> this again we'll understand what profiles we want to preserve.
> Just thinking long term here, but might it make sense to (eventually) 
> allow the user to tune how big a chunk of space to look for?  I know 
> that ext* have options to do this kind of thing, and I think XFS does 
> too (but they do it at filesystem creation time), and I do know people 
> who make use of those to make sure things are working at their absolute 
> best.

Agreed, we have space in the on-disk format to record those preferences, 
but we haven't done it in the past.

-chris