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Re: CVS commit: [tls-maxphys] src/sys/dev

On Tue, Oct 09, 2012 at 10:15:06PM +0200, Manuel Bouyer wrote:
> Now, iostat -x shows that sequential read of a large file (either with cat
> or dd bs=1m) is done in 32k transfers at the disk level. So I guess something
> is not working properly here ...

I saw that too, though I managed to get 64K transfers.  I have been meaning
to test with mmap, since that is more like the code path through the upper
layers that produces the attempt to page in an entire executable.

I've looked all through every layer I can identify and I do not see where
the seemingly still remaining 64K restriction comes from.  I thought it
was FFS, but in fact *every vestige* of the maxcontig or "maximum extent
size" use seems to have been excised from our FFS code.  So it's a mystery
to me.

Chuck, any ideas?


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