Re: Multi CPU Queries - Feedback and/or suggestions wanted!

I couldn't get async I/O to work on Linux. That is it "worked" but  
performed the same as reading one block at a time. On solaris the  
situation is reversed.

In what way is fadvise a kludge?

greg

On 24 Oct 2008, at 01:44 AM, Bruce Momjian <bruce@momjian.us> wrote:

> Jonah H. Harris wrote:
>> On Thu, Oct 23, 2008 at 4:53 PM, Greg Smith <gsmith@gregsmith.com>  
>> wrote:
>>>> I think the current plan is to use posix_advise() to allow  
>>>> parallel I/O,
>>>> rather than async I/O becuase posix_advise() will require fewer  
>>>> code
>>>> changes.
>>>
>>> These are not necessarily mutually exclusive designs.  fadvise  
>>> works fine on
>>> Linux, but as far as I know only async I/O works on Solaris.   
>>> Linux also has
>>> an async I/O library, and it's not clear to me yet whether that  
>>> might work
>>> even better than the fadvise approach.
>>
>> fadvise is a kludge.  While it will help, it still makes us  
>> completely
>> reliant on the OS.  For performance reasons, we should be  
>> supporting a
>> multi-block read directly into shared buffers.  IIRC, we currently
>> have support for rings in the buffer pool, which we could read
>> directly into.  Though, an LRU-based buffer manager design would be
>> more optimal in this case.
>
> True, it is a kludge but if it gives us 95% of the benfit with 10% of
> the code, it is a win.
>
> -- 
>  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
>  EnterpriseDB                             http://enterprisedb.com
>
>  + If your life is a hard drive, Christ can be your backup. +
>
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