Re: [RFC PATCH 0/4]: affinity-on-next-touch

From: Brice Goglin
Date: Mon Jun 22 2009 - 16:34:33 EST

Stefan Lankes wrote:
> By the way, do you also add Lee's "shared policy" patches? These
> patches add MPOL_MF_SHARED, which is specified as 3. Afterwards, you
> have to define MPOL_MF_LAZY as 4.

Yes, I applied shared-policy-* since migrate-on-fault doesn't apply
without them :)

But I have the following in include/linux/mempolicy.h after applying all
#define MPOL_MF_LAZY (1<<3) /* Modifies '_MOVE: lazy migrate on
fault */
#define MPOL_F_SHARED (1 << 0) /* identify shared policies */
Where did you get your F_SHARED=3 and MF_LAZY=4?

> I got following performance results with MPOL_NOOP:
> # Nb_pages Cost(ns)
> 32768 50431375
> 65536 101970000
> 131072 216200500
> 262144 511706000

Is there any migration here? Don't you just have unmap and fault without
migration? In my test program, the initialization does MPOL_BIND. So the
following MPOL_NOOP should just do nothing since the page is already
correctly placed with regard to the previous MPOL_BIND. I feel like 2us
per page looks too low for a migration and it's also very high for just
unmap and fault-in.

> I got following performance results with MPOL_PREFERRED:
> # Nb_pages Cost(ns)
> 32768 141738000

That's about 60% faster than on my machine (quad-barcelona 8347HE
1.9GHz). What machine are you running on?


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at