Re: [PATCH v8 1/7] mm: Add per-cpu logic to page shuffling
From: Dan Williams
Date: Fri Sep 06 2019 - 13:33:56 EST
On Fri, Sep 6, 2019 at 7:53 AM Alexander Duyck
> From: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
> Change the logic used to generate randomness in the suffle path so that we
> can avoid cache line bouncing. The previous logic was sharing the offset
> and entropy word between all CPUs. As such this can result in cache line
> bouncing and will ultimately hurt performance when enabled.
> To resolve this I have moved to a per-cpu logic for maintaining a unsigned
> long containing some amount of bits, and an offset value for which bit we
> can use for entropy with each call.
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>