Re: Use of READDIRPLUS on large directories

[Bryan Schumaker <bjschuma@netapp.com>]

I've done some more testing and posted my initial results here: https://wiki.linux-nfs.org/wiki/index.php/Readdir_performance_results.  If anybody has suggestions for better ways to organize the data, please let me know.  I'll also try to post some graphs in the next couple of days.

- Bryan

On 03/17/2011 01:18 PM, J. Bruce Fields wrote:
> On Thu, Mar 17, 2011 at 09:40:19AM +1100, NeilBrown wrote:
>> On Wed, 16 Mar 2011 17:42:35 -0400 Trond Myklebust
>> <Trond.Myklebust@netapp.com> wrote:
>>
>>  
>>>> So it is obvious that there is sometimes value in using readdirplus,
>>>> it is equally obvious that there is sometimes a cost.
>>>>
>>>> Switching the default from "not paying the cost when it is big" to
>>>> "always paying the cost" is wrong.
>>>
>>> That's what the nordirplus mount flag is for. Keeping an arbitrary limit
>>> in the face of evidence that it is hurting is equally wrong.
>>>
>>
>> If people didn't need 'nordirplus' previously to get acceptable
>> performance, and do need it now, then that is a regression.
> 
> Agreed.
> 
> Unfortunately, reversion at this point would also be a regression for a
> different group of folks.  A smaller one, since *their* problem was
> fixed only more recently, but still there's probably no sensible way out
> of this but forwards....
> 
> --b.