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Re: [PATCH v6 01/15] xen/common: add cache coloring common code


  • To: Carlo Nonato <carlo.nonato@xxxxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Thu, 1 Feb 2024 13:18:55 +0100
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  • Cc: andrea.bastoni@xxxxxxxxxxxxxxx, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Marco Solieri <marco.solieri@xxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 01 Feb 2024 12:19:03 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 29.01.2024 18:17, Carlo Nonato wrote:
> --- /dev/null
> +++ b/docs/misc/cache-coloring.rst
> @@ -0,0 +1,87 @@
> +Xen cache coloring user guide
> +=============================
> +
> +The cache coloring support in Xen allows to reserve Last Level Cache (LLC)
> +partitions for Dom0, DomUs and Xen itself. Currently only ARM64 is supported.
> +
> +To compile LLC coloring support set ``CONFIG_LLC_COLORING=y``.
> +
> +If needed, change the maximum number of colors with
> +``CONFIG_NR_LLC_COLORS=<n>``.
> +
> +Compile Xen and the toolstack and then configure it via
> +`Command line parameters`_.
> +
> +Background
> +**********
> +
> +Cache hierarchy of a modern multi-core CPU typically has first levels 
> dedicated
> +to each core (hence using multiple cache units), while the last level is 
> shared
> +among all of them. Such configuration implies that memory operations on one
> +core (e.g. running a DomU) are able to generate interference on another core
> +(e.g .hosting another DomU). Cache coloring allows eliminating this
> +mutual interference, and thus guaranteeing higher and more predictable
> +performances for memory accesses.

Since you say "eliminating" - what about shared mid-level caches? What about
shared TLBs?

Jan



 


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