On Fri, Jul 20, 2007 at 01:34:42PM +0200, Andi Kleen wrote:
> Fengguang Wu <[EMAIL PROTECTED]> writes:
>
> > Use 'unsigned int' instead of 'unsigned long' for the readahead
> > indexes/sizes.
> >
> > This helps reduce memory consumption on 64bit CPU when
> > a lot of files are opened.
> >
> > Note that the (smaller) 32bit index can support up to 16PB file.
~~~~
sorry, it's 16TB ;)
> > Which should be sufficient large at least for now.
>
> This would add a new limit to 64bit architectures. Surely keeping
> start at pgoff_t will not be a big issue? The other fields can be
> 32bit.
Yeah, it counts for about 4MB memory for 1M opened files.
But, the filp size is now 296 on x86_64, so slab-objects-per-page = 13.
Adding another 4bytes, it remains in 13;
Taking 4bytes more, it increases to 14.
So pgoff_t consumes no more memory actually.
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