Re: [Firebird-devel] FB 2.1 64bit and memory usage ??

[Fred P. <fps...@ya...>]

On 07/26/2007 03:37 AM, Vlad Horsun wrote:
>> ...E.g.,
>> AIX typically wants 4k alignment, except for JFS+big_file
>> filesystems, which want 128k alignment.

Oops!! Bad example. I misread my notes. The alignment is 4k
for AIX JFS+big_file filesystem and the file offset and
transfer sizes should be multiples of 128k.

Guess it's time for sleep! ;-)
...
>     Silent fallback to non-direct I/O. 

Sounds good.

> If direct IO is not supported it
> must be detected when FB tried to switch it on, not when real IO
> is performed. 

If you decide to use O_DIRECT, the open() call may report if
O_DIRECT isn't supported on that file.  But, at that point,
the OS won't know what I/O alignment you'll be using later.
So, a downstream read/write may still fail, on some
implementations, if param. alignments aren't right.

Hmmm. I suppose you could check I/O alignments yourself. For
example, fstat() the file descriptor after the open() and get
that file's filesystem block size.

...
>     Tell me when (if) you ready and if you'll need any help (with FB 
> sources) from my side.

I'm not sure when I can test.  Are your source changes checked
into CVS or available for download?

Fred P.