linux-kernel - Re: [PATCH v3 0/8] x86/resctrl: Add support for Sub-NUMA cluster (SNC) systems

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Message-ID: <ZLw6PpPV5H546VSJ@agluck-desk3>
Date:   Sat, 22 Jul 2023 13:21:18 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>,
        "x86@...nel.org" <x86@...nel.org>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>
Subject: Re: [PATCH v3 0/8] x86/resctrl: Add support for Sub-NUMA cluster
 (SNC) systems

On Wed, Jul 19, 2023 at 02:43:20AM +0000, Shaopeng Tan (Fujitsu) wrote:
> Hi tony,
> 
> I ran selftest/resctrl in my environment,
> the test result is "not ok".
> 
> Processer in my environment:
> Intel(R) Xeon(R) Gold 6254 CPU @ 3.10GHz
> 
> kernel:
> $ uname -r
> 6.5.0-rc1+
> 
> Result :
> Sub-NUMA enable:
> xxx@xxx:~/linux_v6.5_rc1l$ sudo make -C tools/testing/selftests/resctrl run_tests
> make: Entering directory '/.../tools/testing/selftests/resctrl'

I see most tests pass. Just one fail on my most recent run with the
v4 patch series:

# # Fail: Check MBA diff within 5% for schemata 10
# # avg_diff_per: 7%
# # avg_bw_imc: 883
# # avg_bw_resc: 815
# # Fail: Check schemata change using MBA

But just missed the 5% target by a small amount,
not the near total failures that you see.

I wonder if there is a cross-SNC node memory
allocation issue.  Can you try running the test
bound to a CPU in one node:

$ taskset -c 1 sudo make -C tools/testing/selftests/resctrl run_tests

Try with different "-c" arguments to bind to different nodes. Do you
see different results on differnt nodes?

-Tony