From: "Moger, Babu" <Babu.Moger@amd.com>
To: Reinette Chatre <reinette.chatre@intel.com>,
"corbet@lwn.net" <corbet@lwn.net>,
"tglx@linutronix.de" <tglx@linutronix.de>,
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"bp@alien8.de" <bp@alien8.de>
Cc: "fenghua.yu@intel.com" <fenghua.yu@intel.com>,
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Subject: RE: [PATCH v4 01/13] x86/resctrl: Fix min_cbm_bits for AMD
Date: Fri, 16 Sep 2022 18:31:05 +0000 [thread overview]
Message-ID: <MW3PR12MB4553557C746E9B432AA5935195489@MW3PR12MB4553.namprd12.prod.outlook.com> (raw)
In-Reply-To: <7c88b2e8-2cc9-404e-7167-6743d796b0cf@intel.com>
[AMD Official Use Only - General]
> -----Original Message-----
> From: Reinette Chatre <reinette.chatre@intel.com>
> Sent: Friday, September 16, 2022 10:53 AM
> To: Moger, Babu <Babu.Moger@amd.com>; corbet@lwn.net;
> tglx@linutronix.de; mingo@redhat.com; bp@alien8.de
> Cc: fenghua.yu@intel.com; dave.hansen@linux.intel.com; x86@kernel.org;
> hpa@zytor.com; paulmck@kernel.org; akpm@linux-foundation.org;
> quic_neeraju@quicinc.com; rdunlap@infradead.org;
> damien.lemoal@opensource.wdc.com; songmuchun@bytedance.com;
> peterz@infradead.org; jpoimboe@kernel.org; pbonzini@redhat.com;
> chang.seok.bae@intel.com; pawan.kumar.gupta@linux.intel.com;
> jmattson@google.com; daniel.sneddon@linux.intel.com; Das1, Sandipan
> <Sandipan.Das@amd.com>; tony.luck@intel.com; james.morse@arm.com;
> linux-doc@vger.kernel.org; linux-kernel@vger.kernel.org;
> bagasdotme@gmail.com; eranian@google.com
> Subject: Re: [PATCH v4 01/13] x86/resctrl: Fix min_cbm_bits for AMD
>
> Hi Babu,
>
> On 9/7/2022 10:59 AM, Babu Moger wrote:
> > AMD systems support zero CBM (capacity bit mask) for L3 allocation.
>
> Above mentions "for L3 allocation", but the change impacts
> L3 as well as L2 allocation. Perhaps just "cache allocation"?
>
> > That is reflected in rdt_init_res_defs_amd() by:
> >
> > r->cache.arch_has_empty_bitmaps = true;
> >
> > However given the unified code in cbm_validate(), checking for:
> > val == 0 && !arch_has_empty_bitmaps
> >
> > is not enough because of another check in cbm_validate():
> >
> > if ((zero_bit - first_bit) < r->cache.min_cbm_bits)
> >
> > The default value of r->cache.min_cbm_bits = 1.
> >
> > Leading to:
> >
> > $ cd /sys/fs/resctrl
> > $ mkdir foo
> > $ cd foo
> > $ echo L3:0=0 > schemata
> > -bash: echo: write error: Invalid argument
> > $ cat /sys/fs/resctrl/info/last_cmd_status
> > Need at least 1 bits in the mask
> >
> > Fix the issue by initializing the min_cbm_bits to 0 for AMD. Also,
> > remove the default setting of min_cbm_bits and initialize it separately.
> >
> > After the fix
> > $ cd /sys/fs/resctrl
> > $ mkdir foo
> > $ cd foo
> > $ echo L3:0=0 > schemata
> > $ cat /sys/fs/resctrl/info/last_cmd_status
> > ok
> >
> > Link:
> > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore
> > .kernel.org%2Flkml%2F20220517001234.3137157-1-
> eranian%40google.com%2F&
> >
> amp;data=05%7C01%7Cbabu.moger%40amd.com%7Cfdccc20e6a234fb3872a0
> 8da97fb
> >
> 94fc%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C6379894040498
> 44076%7
> >
> CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI
> 6Ik1
> >
> haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=DIpkBAkI7lAjj5QQ4
> 5VahssT
> > dWGj%2FcUwGJDiHXNYzz8%3D&reserved=0
> > Fixes: 316e7f901f5a ("x86/resctrl: Add struct
> > rdt_cache::arch_has_{sparse, empty}_bitmaps")
> > Signed-off-by: Stephane Eranian <eranian@google.com>
> > Signed-off-by: Babu Moger <babu.moger@amd.com>
> > Reviewed-by: Ingo Molnar <mingo@kernel.org>
>
> (apart from the changelog nitpick)
>
> Thank you for clarifying the way forward for this fix.
>
> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Thank you
Babu Moger
next prev parent reply other threads:[~2022-09-16 18:31 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-07 17:59 [PATCH v4 00/13] x86/resctrl: Support for AMD QoS new features and bug fix Babu Moger
2022-09-07 17:59 ` [PATCH v4 01/13] x86/resctrl: Fix min_cbm_bits for AMD Babu Moger
2022-09-09 17:00 ` James Morse
2022-09-12 14:54 ` Moger, Babu
2022-09-16 15:52 ` Reinette Chatre
2022-09-16 18:28 ` Moger, Babu
2022-09-16 15:53 ` Reinette Chatre
2022-09-16 18:31 ` Moger, Babu [this message]
2022-09-07 18:00 ` [PATCH v4 02/13] x86/resctrl: Remove arch_has_empty_bitmaps Babu Moger
2022-09-16 15:53 ` Reinette Chatre
2022-09-16 19:00 ` Moger, Babu
2022-09-07 18:00 ` [PATCH v4 03/13] x86/cpufeatures: Add Slow Memory Bandwidth Allocation feature flag Babu Moger
2022-09-16 15:54 ` Reinette Chatre
2022-09-16 19:02 ` Moger, Babu
2022-09-07 18:00 ` [PATCH v4 04/13] x86/resctrl: Add a new resource type RDT_RESOURCE_SMBA Babu Moger
2022-09-16 15:54 ` Reinette Chatre
2022-09-16 19:11 ` Moger, Babu
2022-09-07 18:00 ` [PATCH v4 05/13] x86/cpufeatures: Add Bandwidth Monitoring Event Configuration feature flag Babu Moger
2022-09-07 18:36 ` Daniel Sneddon
2022-09-07 19:59 ` Moger, Babu
2022-09-16 15:55 ` Reinette Chatre
2022-09-16 20:19 ` Moger, Babu
2022-09-07 18:00 ` [PATCH v4 06/13] x86/resctrl: Include new features in command line options Babu Moger
2022-09-16 15:55 ` Reinette Chatre
2022-09-16 20:22 ` Moger, Babu
2022-09-07 18:00 ` [PATCH v4 07/13] x86/resctrl: Detect and configure Slow Memory Bandwidth allocation Babu Moger
2022-09-07 18:00 ` [PATCH v4 08/13] x86/resctrl : Introduce data structure to support monitor configuration Babu Moger
2022-09-16 15:56 ` Reinette Chatre
2022-09-16 21:23 ` Moger, Babu
2022-09-07 18:01 ` [PATCH v4 09/13] x86/resctrl: Add sysfs interface files to read/write event configuration Babu Moger
2022-09-16 15:58 ` Reinette Chatre
2022-09-19 15:46 ` Moger, Babu
2022-09-19 16:42 ` Reinette Chatre
2022-09-19 20:26 ` Moger, Babu
2022-09-19 21:07 ` Reinette Chatre
2022-09-20 17:09 ` Moger, Babu
2022-09-07 18:01 ` [PATCH v4 10/13] x86/resctrl: Add the sysfs interface to read the " Babu Moger
2022-09-16 15:59 ` Reinette Chatre
2022-09-19 16:07 ` Moger, Babu
2022-09-07 18:01 ` [PATCH v4 11/13] x86/resctrl: Add sysfs interface to write " Babu Moger
2022-09-16 16:17 ` Reinette Chatre
2022-09-19 16:50 ` Moger, Babu
2022-09-07 18:01 ` [PATCH v4 12/13] x86/resctrl: Replace smp_call_function_many with on_each_cpu_mask Babu Moger
2022-09-16 16:17 ` Reinette Chatre
2022-09-16 20:38 ` Moger, Babu
2022-09-07 18:01 ` [PATCH v4 13/13] Documentation/x86: Update resctrl_ui.rst for new features Babu Moger
2022-09-08 4:07 ` Bagas Sanjaya
2022-09-08 9:26 ` Bagas Sanjaya
2022-09-08 13:40 ` Moger, Babu
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