From: Reinette Chatre <reinette.chatre@intel.com>
To: James Morse <james.morse@arm.com>, <x86@kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
H Peter Anvin <hpa@zytor.com>, Babu Moger <Babu.Moger@amd.com>,
<shameerali.kolothum.thodi@huawei.com>,
Jamie Iles <jamie@nuviainc.com>,
"D Scott Phillips OS" <scott@os.amperecomputing.com>,
<lcherian@marvell.com>, <bobo.shaobowang@huawei.com>
Subject: Re: [PATCH v1 06/20] x86/resctrl: Switch over to the resctrl mbps_val list
Date: Wed, 1 Sep 2021 14:25:26 -0700 [thread overview]
Message-ID: <5be446b6-d6f6-dacb-4368-7c1e7aedc6cf@intel.com> (raw)
In-Reply-To: <20210729223610.29373-7-james.morse@arm.com>
Hi James,
On 7/29/2021 3:35 PM, James Morse wrote:
> Updates to resctrl's software controller follow the same path as
> other configuration updates, but they don't modify the hardware state.
> rdtgroup_schemata_write() uses parse_line() and the resource's
> ctrlval_parse function to stage the configuration.
> resctrl_arch_update_domains() then updates the mbps_val[] array
> instead, and resctrl_arch_update_domains() skips the rdt_ctrl_update()
> call that would update hardware.
>
> This complicates the interface between resctrl's filesystem parts
> and architecture specific code. It should be possible for mba_sc
> to be completely implemented by the filesystem parts of resctrl. This
> would allow it to work on a second architecture with no additional code.
>
> Change parse_bw() to write the configuration value directly to the
> mba_sc[] array in the domain structure. Change rdtgroup_schemata_write()
> to skip the call to resctrl_arch_update_domains(), meaning all the
> mba_sc specific code in resctrl_arch_update_domains() can be removed.
> On the read-side, show_doms() and update_mba_bw() are changed to read
> the mba_sc[] array from the domain structure. With this,
> resctrl_arch_get_config() no longer needs to consider mba_sc resources.
>
> Change parse_bw() to write these values directly, meaning
> rdtgroup_schemata_write() never needs to call update_domains()
> for mba_sc resources.
The above paragraph seems to contain duplicate information from the
paragraph that precedes it.
>
> Get show_doms() to test is_mba_sc() and retrieve the value
> directly, instead of using get_config() for the hardware value.
>
> This means the arch code's resctrl_arch_get_config() and
> resctrl_arch_update_domains() no longer need to be aware of
> mba_sc, and we can get rid of the update_mba_bw() code that
> reaches into the hw_dom to get the msr value.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
...
> @@ -406,6 +406,14 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
>
> list_for_each_entry(s, &resctrl_schema_all, list) {
> r = s->res;
> +
> + /*
> + * Writes to mba_sc resources update the software controller,
> + * not the control msr.
> + */
> + if (is_mba_sc(r))
> + continue;
> +
A few resources can be updated in a single write to the schemata file.
It is thus possible to update the cache allocation resource as well as
memory bandwidth allocation in a single write. As I understand this
change in this scenario all configuration updates will be skipped, not
just the memory bandwidth allocation ones.
> ret = resctrl_arch_update_domains(r, rdtgrp->closid);
> if (ret)
> goto out;
Reinette
next prev parent reply other threads:[~2021-09-01 21:25 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-29 22:35 [PATCH v1 00/20] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse
2021-07-29 22:35 ` [PATCH v1 01/20] x86/resctrl: Kill off alloc_enabled James Morse
2021-08-11 12:12 ` Jamie Iles
2021-09-01 21:18 ` Reinette Chatre
2021-07-29 22:35 ` [PATCH v1 02/20] x86/resctrl: Merge mon_capable and mon_enabled James Morse
2021-08-11 12:15 ` Jamie Iles
2021-08-11 15:16 ` James Morse
2021-07-29 22:35 ` [PATCH v1 03/20] x86/resctrl: Add domain online callback for resctrl work James Morse
2021-09-01 21:19 ` Reinette Chatre
2021-09-17 16:57 ` James Morse
2021-07-29 22:35 ` [PATCH v1 04/20] x86/resctrl: Add domain offline " James Morse
2021-08-11 16:10 ` Jamie Iles
2021-09-01 21:21 ` Reinette Chatre
2021-07-29 22:35 ` [PATCH v1 05/20] x86/resctrl: Create mba_sc configuration in the rdt_domain James Morse
2021-08-11 16:32 ` Jamie Iles
2021-08-31 16:24 ` James Morse
2021-09-01 21:22 ` Reinette Chatre
2021-09-17 16:57 ` James Morse
2021-07-29 22:35 ` [PATCH v1 06/20] x86/resctrl: Switch over to the resctrl mbps_val list James Morse
2021-09-01 21:25 ` Reinette Chatre [this message]
2021-09-17 16:57 ` James Morse
2021-09-17 18:20 ` Reinette Chatre
2021-10-01 16:02 ` James Morse
2021-07-29 22:35 ` [PATCH v1 07/20] x86/resctrl: Remove architecture copy of mbps_val James Morse
2021-09-01 21:26 ` Reinette Chatre
2021-09-17 16:57 ` James Morse
2021-07-29 22:35 ` [PATCH v1 08/20] x86/resctrl: Remove set_mba_sc()s control array re-initialisation James Morse
2021-07-29 22:35 ` [PATCH v1 09/20] x86/resctrl: Abstract and use supports_mba_mbps() James Morse
2021-09-01 21:27 ` Reinette Chatre
2021-09-17 16:57 ` James Morse
2021-09-24 6:23 ` tan.shaopeng
2021-10-01 16:01 ` James Morse
2021-07-29 22:36 ` [PATCH v1 10/20] x86/resctrl: Allow update_mba_bw() to update controls directly James Morse
2021-09-01 21:28 ` Reinette Chatre
2021-07-29 22:36 ` [PATCH v1 11/20] x86/resctrl: Calculate bandwidth from the total bytes counter James Morse
2021-09-01 21:31 ` Reinette Chatre
2021-09-17 16:58 ` James Morse
2021-07-29 22:36 ` [PATCH v1 12/20] x86/recstrl: Add per-rmid arch private storage for overflow and chunks James Morse
2021-08-11 17:14 ` Jamie Iles
2021-08-31 16:25 ` James Morse
2021-07-29 22:36 ` [PATCH v1 13/20] x86/recstrl: Allow per-rmid arch private storage to be reset James Morse
2021-09-24 6:34 ` tan.shaopeng
2021-10-01 16:01 ` James Morse
2021-07-29 22:36 ` [PATCH v1 14/20] x86/resctrl: Abstract __rmid_read() James Morse
2021-07-29 22:36 ` [PATCH v1 15/20] x86/resctrl: Pass the required parameters into resctrl_arch_rmid_read() James Morse
2021-07-29 22:36 ` [PATCH v1 16/20] x86/resctrl: Move mbm_overflow_count() " James Morse
2021-07-29 22:36 ` [PATCH v1 17/20] x86/resctrl: Move get_corrected_mbm_count() " James Morse
2021-07-29 22:36 ` [PATCH v1 18/20] x86/resctrl: Rename and change the units of resctrl_cqm_threshold James Morse
2021-07-29 22:36 ` [PATCH v1 19/20] x86/resctrl: Add resctrl_rmid_realloc_limit to abstract x86's boot_cpu_data James Morse
2021-07-29 22:36 ` [PATCH v1 20/20] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse
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