Re: AIO Support and related package information??

["Sébastien Dugué" <sebastien.dugue@bull.net>]

On Mon, 2005-09-26 at 08:32 +0100, vikas gupta wrote:
> hi Sebastien ,
> 
> I am having yet another query related to AIO Support
> 
> 1)As you mentioned that aio posix support is provided
> by glibc also so can you tell me on the performance
> basis which one is better (glibc implementation or
> libposix implementation ) and how do we measure the
> performance

  Have a look at:
http://www.bullopensource.org/posix/Bench/sysbench-oltp/sysbench.html
for benchmarks using Sysbench and MySQL.

> 
> I have compiled glibc with following command 
> 
> gcc -g $1.c -o $1 -lrt -lpthread 

  Then you're using glibc AIO implementation based on helper threads
and without taking advantage of kernel support.

> 
> 
> 2)What posix features is supported by bare kernel and
> libposix implementation, without applying the
> patches.I have broken down my  query in following
> parts

  Without any of the patches:

> 
> 2.1) aio_read/aio_write  is supported but what
> limitation are there

  Supported but without notification (SIGEV_NONE only).

> 
> 2.2) aio_fsync is supported or not

  Supported only if the underlying fs implements it

> 
> 2.3) what are the limitation with lio_listio

  Not supported wihtout the patches.

> 
> 2.4) what are the additional feature it provides for
> aio_cancel implementation
> 

  Needs support from the underlying fs.

> 
> 3) Is glibc implementation is providing all the above
> mentioned fetures

  Yes, I think so.

> 
> 4) Is there any test program that can measure
> efficiency for both glibc and libposix implementation

  I personally use Sysbench and have compiled 3 MySQL servers,
one with librt AIO, one with libposix-aio and one with MySQL
native simulated AIO.

  You may also try iozone.

> 
> 
> With Thanks in advance 
> Vikas 


  Hope this helps,

  Sébastien.

-- 
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  Sébastien Dugué                BULL/FREC:B1-247
  phone: (+33) 476 29 77 70      Bullcom: 229-7770

  mailto:sebastien.dugue@bull.net

  Linux POSIX AIO: http://www.bullopensource.org/posix
  
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