[ofa-general] [PATCH] IB/mlx4: Use pgprot_writecombine() for BlueFlame pages

[Roland Dreier]

 > Again, the facts are that on my latest round of testing I got a
 > latency of 1.4us with and without X86_PAT which went down to 1.1us
 > when applying your patch on top of a X86_PAT config. Even if I'm doing
 > something wrong, I still want to see that we understand each
 > other... so please let me know if you still don't understand me.

Those results make sense.  The only thing you said that I don't understand:

 > I noted that I have CONFIG_MTRR=y so maybe this can explain the nice latency
 > even without setting X86_PAT?

But you are getting the worse latency without X86_PAT -- you need
X86_PAT and a patch to use PAT in mlx4_ib to get better latency, which
is as I expect.  So I'm not sure why you talk about "nice" latency
without X86_PAT.

 - R.