[Pvfs2-users] Re: 2.8.1 question

[Phil Carns]

Hi Brad,

Are you talking about on the back end (how the servers perform I/O to 
their storage devices) or in the interface to the file system?

On the back end, there are three trove method options:
- dbpf: uses glibc aio
- alt-aio: uses pread/pwrite and threads (this is the default)
- directio: uses O_DIRECT and threads

I assume the experimental option you are looking at is 
"--disable-aio-threaded-callbacks".  That option only affects the first 
method above (dbpf).  Even then, however, it does not disable glibc aio, 
it just changes the mechanism that glibc aio uses to notify completion 
(the callback approach used to be buggy in ancient versions of glibc).

Those are all independent of the client interface, which depending on 
which interface you are using may have its own async functions.

-Phil

Bradley Settlemyer wrote:
> I notice now that disabling that feature is experimental.  How
> experimental exactly, as aio isn't really the behavior I want?
> 
> Cheers,
> Brad
> 
> 
> On Sun, Mar 8, 2009 at 8:22 PM, Bradley Settlemyer
> <bradles at parl.clemson.edu> wrote:
>> Does PVFS 2.8.1 use async IO?
>>
>> Cheers,
>> Brad
>>
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