Re: [PATCH 13/32] Documentation, x86: Documentation for Intel resource allocation user interface
From: Nilay Vaish
Date: Wed Jul 27 2016 - 12:21:16 EST
On 12 July 2016 at 20:02, Fenghua Yu <fenghua.yu@xxxxxxxxx> wrote:
> +1. Terms
> +We use the following terms and concepts in this documentation.
> +RDT: Intel Resoure Director Technology
> +CAT: Cache Allocation Technology
> +CDP: Code and Data Prioritization
> +CBM: Cache Bit Mask
> +Cache ID: A cache identification. It is unique in one cache index on the
> +platform. User can find cache ID in cache sysfs interface:
> +Share resource domain: A few different resources can share same QoS mask
> +MSRs array. For example, one L2 cache can share QoS MSRs with its next level
> +L3 cache. A domain number represents the L2 cache, the L3 cache, the L2
> +cache's shared cpumask, and the L3 cache's shared cpumask.
I think CLOS ID should be defined here. Is it same as Cache ID?
> +As one example, CAT L3's schema format is:
> +On a two socket machine, L3's schema line could be:
> +which means this line in "schemas" file is for CAT L3, L3 cache id 0's CBM
> +is 0xff, and L3 cache id 1's CBM is 0xc0.
> +If one resource is disabled, its line is not shown in schemas file.
> +The schema line can be expended for situations. L3 cbms format can be
> +expended to CDP enabled L3 cbms format:
> +Initial value is all ones which means all tasks use all resources initially.
Your example here makes me feel that Cache ID and CLOS ID mean the same thing.
> +7. Some usage examples
> +7.1 Example 1 for sharing CLOSID on socket 0 between two partitions
> +Only L3 cbm is enabled. Assume the machine is 2-socket and dual-core without
> +#mount -t rscctrl rscctrl /sys/fs/rscctrl
> +#cd /sys/fs/rscctrl
> +#mkdir p0 p1
> +#echo "L3:0=3;1=c" > /sys/fs/rscctrl/p0/schemas
> +#echo "L3:0=3;1=3" > /sys/fs/rscctrl/p1/schemas
> +In partition p0, kernel allocates CLOSID 0 for L3 cbm=0x3 on socket 0 and
> +CLOSID 0 for cbm=0xc on socket 1.
> +In partition p1, kernel allocates CLOSID 0 for L3 cbm=0x3 on socket 0 and
> +CLOSID 1 for cbm=0x3 on socket 1.
And over here you have switched to using CLOS ID and you do not
mention Cache ID at all.
As I said above, I think Cache ID and CLOS ID are the same thing. If
that is the case, I think Cache ID should be completely replaced with