linux-kernel - Re: [PATCH 22/22] selftests/resctrl: Rewrite Cache Allocation Technology (CAT) test

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Message-ID: <9912c0bd-f1c8-1f27-17a0-2a3d48279e75@linux.intel.com>
Date:   Thu, 13 Apr 2023 13:12:30 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     linux-kselftest@...r.kernel.org
cc:     LKML <linux-kernel@...r.kernel.org>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Shuah Khan <shuah@...nel.org>,
        Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Subject: Re: [PATCH 22/22] selftests/resctrl: Rewrite Cache Allocation
 Technology (CAT) test

On Wed, 12 Apr 2023, Ilpo Järvinen wrote:

> Rewrite the CAT test to allocated a buffer sized to half of LLC. Then
> perform a sequence of tests with different LLC block sizes starting
> from 1-bit CBM to half of the CBM bits. Flush the buffer before each
> test and read the buffer twice. Observe the LLC misses on the second
> read through the buffer. As the allocated LLC block gets larger and
> larger, the LLC misses will become smaller and smaller giving a strong
> signal on CAT working properly.

I realized this description is now wrong way around as I at one point 
reversed the cache allocation mask to go from half of CBM bits to 1-bit 
but didn't remember to update the changelog (in case somebody ends up 
wondering why it doesn't match to what the code does). V2 will contain the 
correct way around description.


-- 
 i.