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Message-ID: <c4ec0e32-5c4e-4c83-bc9d-4bdfd3474ca8@amd.com>
Date: Mon, 7 Apr 2025 15:18:16 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com
Cc: x86@...nel.org, hpa@...or.com, akpm@...ux-foundation.org,
paulmck@...nel.org, thuth@...hat.com, rostedt@...dmis.org,
xiongwei.song@...driver.com, pawan.kumar.gupta@...ux.intel.com,
jpoimboe@...nel.org, daniel.sneddon@...ux.intel.com,
thomas.lendacky@....com, perry.yuan@....com, sandipan.das@....com,
kai.huang@...el.com, seanjc@...gle.com, xin3.li@...el.com,
ebiggers@...gle.com, andrew.cooper3@...rix.com, mario.limonciello@....com,
tan.shaopeng@...itsu.com, james.morse@....com, tony.luck@...el.com,
peternewman@...gle.com, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, eranian@...gle.com, corbet@....net
Subject: Re: [PATCH v3 6/7] x86/resctrl: Introduce interface to display
io_alloc CBMs
Hi Reinette,
On 3/21/25 17:58, Reinette Chatre wrote:
> Hi Babu,
>
> On 1/30/25 1:20 PM, Babu Moger wrote:
>> The io_alloc feature in resctrl enables system software to configure
>> the portion of the L3 cache allocated for I/O traffic.
>>
>> Add the interface to display CBMs (Capacity Bit Mask) of io_alloc
>> feature.
>>
>> When CDP is enabled, io_alloc routes traffic using the highest CLOSID
>> which corresponds to CDP_CODE. Add a check for the CDP resource type.
>
> It is not obvious to me what is meant with "highest CLOSID
> which corresponds to CDP_CODE" ... how about "highest CLOSID used by
> a L3CODE resource"?
Yes. That is correct.
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v3: Minor changes due to changes in resctrl_arch_get_io_alloc_enabled()
>> and resctrl_io_alloc_closid_get().
>> Added the check to verify CDP resource type.
>> Updated the commit log.
>>
>> v2: Fixed to display only on L3 resources.
>> Added the locks while processing.
>> Rename the displat to io_alloc_cbm (from sdciae_cmd).
>> ---
>> arch/x86/kernel/cpu/resctrl/core.c | 2 ++
>> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 2 +-
>> arch/x86/kernel/cpu/resctrl/internal.h | 1 +
>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 38 +++++++++++++++++++++++
>> 4 files changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
>> index 88bc95c14ea8..030f738dea8d 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -311,6 +311,8 @@ static void rdt_set_io_alloc_capable(struct rdt_resource *r)
>> r->cache.io_alloc_capable = true;
>> resctrl_file_fflags_init("io_alloc",
>> RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE);
>> + resctrl_file_fflags_init("io_alloc_cbm",
>> + RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE);
>> }
>>
>> static void rdt_get_cdp_l3_config(void)
>> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
>> index 536351159cc2..d272dea43924 100644
>> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
>> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
>> @@ -444,7 +444,7 @@ u32 resctrl_arch_get_config(struct rdt_resource *r, struct rdt_ctrl_domain *d,
>> return hw_dom->ctrl_val[idx];
>> }
>>
>> -static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid)
>> +void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid)
>> {
>> struct rdt_resource *r = schema->res;
>> struct rdt_ctrl_domain *dom;
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index 61bc609e932b..07cf8409174d 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -668,4 +668,5 @@ void resctrl_file_fflags_init(const char *config, unsigned long fflags);
>> void rdt_staged_configs_clear(void);
>> bool closid_allocated(unsigned int closid);
>> int resctrl_find_cleanest_closid(void);
>> +void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid);
>> #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 37295dd14abe..81b9d8c5dabf 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -1967,6 +1967,38 @@ static ssize_t resctrl_io_alloc_write(struct kernfs_open_file *of, char *buf,
>> return ret ?: nbytes;
>> }
>>
>> +static int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of,
>> + struct seq_file *seq, void *v)
>> +{
>> + struct resctrl_schema *s = of->kn->parent->priv;
>> + struct rdt_resource *r = s->res;
>> + u32 io_alloc_closid;
>> + int ret = 0;
>> +
>> + if (!r->cache.io_alloc_capable || s->conf_type == CDP_DATA) {
>> + rdt_last_cmd_puts("io_alloc feature is not supported on the resource\n");
>
> rdt_last_cmd_puts() has to be called with rdtgroup_mutex held, also clear it before use.
Sure.
>
>> + return -EINVAL;
>
> How about ENODEV?
Sure.
>
>> + }
>> +
>> + cpus_read_lock();
>> + mutex_lock(&rdtgroup_mutex);
>> +
>> + if (!resctrl_arch_get_io_alloc_enabled(r)) {
>> + rdt_last_cmd_puts("io_alloc feature is not enabled\n");
>> + ret = -EINVAL;
>> + goto cbm_show_out;
>> + }
>> +
>> + io_alloc_closid = resctrl_io_alloc_closid_get(r, s);
>> +
>> + show_doms(seq, s, io_alloc_closid);
>> +
>> +cbm_show_out:
>> + mutex_unlock(&rdtgroup_mutex);
>> + cpus_read_unlock();
>> + return ret;
>> +}
>> +
>> /* rdtgroup information files for one cache resource. */
>> static struct rftype res_common_files[] = {
>> {
>> @@ -2126,6 +2158,12 @@ static struct rftype res_common_files[] = {
>> .seq_show = resctrl_io_alloc_show,
>> .write = resctrl_io_alloc_write,
>> },
>> + {
>> + .name = "io_alloc_cbm",
>> + .mode = 0444,
>> + .kf_ops = &rdtgroup_kf_single_ops,
>> + .seq_show = resctrl_io_alloc_cbm_show,
>> + },
>> {
>> .name = "mba_MBps_event",
>> .mode = 0644,
>
> Reinette
>
--
Thanks
Babu Moger
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