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? Thor