On Wed, 2011-09-07 at 20:31 +0800, Wu Fengguang wrote:

quoted

quoted

+   x_intercept = min(write_bw, freerun);
+   if (bdi_dirty < x_intercept) {

So the point of the freerun point is that we never throttle before it,
so basically all the below shouldn't be needed at all, right? 

Yes!

quoted

quoted

+           if (bdi_dirty > x_intercept / 8) {
+                   pos_ratio *= x_intercept;
+                   do_div(pos_ratio, bdi_dirty);
+           } else
+                   pos_ratio *= 8;
+   }
+
    return pos_ratio;
 }

Does that mean we can remove this whole block?

quoted

So why not add:

      if (likely(dirty < freerun))
              return 2;

at the start of this function and leave it at that?

Because we already has

        if (nr_dirty < freerun)
                break;

in the main balance_dirty_pages() loop ;)

Bah! I keep missing that ;-)

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