| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <659b7776-573a-43bb-9ea9-cf957af25238@amd.com>
Date: Fri, 20 Jun 2025 16:57:41 -0500
From: "Moger, Babu" <bmoger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>,
Babu Moger <babu.moger@....com>, corbet@....net, tony.luck@...el.com,
Dave.Martin@....com, james.morse@....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, rostedt@...dmis.org, thuth@...hat.com, ardb@...nel.org,
gregkh@...uxfoundation.org, seanjc@...gle.com, thomas.lendacky@....com,
pawan.kumar.gupta@...ux.intel.com, perry.yuan@....com,
yosry.ahmed@...ux.dev, kai.huang@...el.com, xiaoyao.li@...el.com,
peterz@...radead.org, kan.liang@...ux.intel.com, mario.limonciello@....com,
xin3.li@...el.com, sohil.mehta@...el.com, chang.seok.bae@...el.com,
andrew.cooper3@...rix.com, ebiggers@...gle.com, ak@...ux.intel.com,
xin@...or.com, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 6/8] fs/resctrl: Introduce interface to display
io_alloc CBMs
Hi Reinette,
On 6/17/2025 11:01 PM, Reinette Chatre wrote:
> Hi Babu,
>
> On 6/11/25 2:23 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.
>
> Drop L3?
Sure.
>>
>> Add the interface to display CBMs (Capacity Bit Mask) of io_alloc
>> feature.
>
> After the fs/arch split it is not always obvious what is meant with
> "interface" ... it could be new API between fs and arch or it could be
> new resctrl file.
> This can be specific:
> Add "io_alloc_cbm" resctrl file to display ...
>
Sure.
>>
>> The CBM interface file io_alloc_cbm will reside in the info directory
>> (e.g., /sys/fs/resctrl/info/L3/). Displaying the resource name is not
>> necessary. Pass the resource name to show_doms() and print it only if
>> the name is valid. For io_alloc, pass NULL to suppress printing the
>> resource name.
>>
>> When CDP is enabled, io_alloc routes traffic using the highest CLOSID
>> associated with an L3CODE resource. However, CBMs can be accessed via
>> either L3CODE or L3DATA resources.
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>
> ...
>
>> ---
>> Documentation/filesystems/resctrl.rst | 13 +++++++
>> fs/resctrl/ctrlmondata.c | 8 +++--
>> fs/resctrl/internal.h | 2 ++
>> fs/resctrl/rdtgroup.c | 51 ++++++++++++++++++++++++++-
>> 4 files changed, 70 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
>> index 03c829b2c276..b31748ec8c61 100644
>> --- a/Documentation/filesystems/resctrl.rst
>> +++ b/Documentation/filesystems/resctrl.rst
>> @@ -169,6 +169,19 @@ related to allocation:
>> When CDP is enabled, io_alloc routes I/O traffic using the highest
>> CLOSID allocated for the instruction cache (L3CODE).
>>
>> +"io_alloc_cbm":
>> + Capacity Bit Masks (CBMs) available to supported IO devices which
>> + can directly insert cache lines in L3 which can help to reduce the
>
> "CBMs that describe the portions of cache instances to which I/O traffic
> from supported IO devices are routed."
Sure.
> Please check ... there seems to be some inconsistency in "IO" vs "I/O" use.
Changed to "I/O" in all the places.
>
> Also consider something like,
> "When CDP is enabled "io_alloc_cbm" associated with the DATA
> and CODE resources may reflect the same values. For example, values read from
> and written to /sys/fs/resctrl/info/L3DATA/io_alloc_cbm may be reflected by
> /sys/fs/resctrl/info/L3CODE/io_alloc_cbm and vice versa."
> What do you think?
Looks good.
>
>> + latency. CBMs are displayed in the following format:
>> +
>> + <cache_id0>=<cbm>;<cache_id1>=<cbm>;...
>> +
>> + Example::
>> +
>> + # cat /sys/fs/resctrl/info/L3/io_alloc_cbm
>> + 0=ffff;1=ffff
>> +
>> +
>> Memory bandwidth(MB) subdirectory contains the following files
>> with respect to allocation:
>>
>> diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
>> index 6ed2dfd4dbbd..ea039852569a 100644
>> --- a/fs/resctrl/ctrlmondata.c
>> +++ b/fs/resctrl/ctrlmondata.c
>> @@ -381,7 +381,8 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
>> return ret ?: nbytes;
>> }
>>
>> -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, char *resource_name,
>> + int closid)
>> {
>> struct rdt_resource *r = schema->res;
>> struct rdt_ctrl_domain *dom;
>> @@ -391,7 +392,8 @@ static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int clo
>> /* Walking r->domains, ensure it can't race with cpuhp */
>> lockdep_assert_cpus_held();
>>
>> - seq_printf(s, "%*s:", max_name_width, schema->name);
>> + if (resource_name)
>> + seq_printf(s, "%*s:", max_name_width, resource_name);
>> list_for_each_entry(dom, &r->ctrl_domains, hdr.list) {
>> if (sep)
>> seq_puts(s, ";");
>> @@ -437,7 +439,7 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of,
>> closid = rdtgrp->closid;
>> list_for_each_entry(schema, &resctrl_schema_all, list) {
>> if (closid < schema->num_closid)
>> - show_doms(s, schema, closid);
>> + show_doms(s, schema, schema->name, closid);
>> }
>> }
>> } else {
>> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
>> index 9a8cf6f11151..14f3697c1187 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -374,6 +374,8 @@ 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,
>> + char *name, int closid);
>>
>> #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
>> int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index bbc032b4d0e9..0c2d2cf4baa1 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -1997,6 +1997,46 @@ 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 = rdt_kn_parent_priv(of->kn);
>> + struct rdt_resource *r = s->res;
>> + u32 io_alloc_closid;
>> + int ret = 0;
>> +
>> + cpus_read_lock();
>> + mutex_lock(&rdtgroup_mutex);
>> +
>> + rdt_last_cmd_clear();
>> +
>> + if (!r->cache.io_alloc_capable) {
>> + rdt_last_cmd_puts("io_alloc feature is not supported on the resource\n");
>> + ret = -ENODEV;
>> + goto cbm_show_out;
>
> out_unlock
>
Sure.
>> + }
>> +
>> + 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);
>> + if (io_alloc_closid < 0) {
>
> Another example where io_alloc_closid must be valid thanks to earlier resctrl_arch_get_io_alloc_enabled(r).
Sure. Will remove this check.
>
>> + rdt_last_cmd_puts("Max CLOSID to support io_alloc is not available\n");
>> + ret = -EINVAL;
>> + goto cbm_show_out;
>> + }
>> +
>> + show_doms(seq, resctrl_schema_io_alloc(s), NULL, io_alloc_closid);
>> +
>> +cbm_show_out:
>
> out_unlock ... to match rest of resctrl
sure.
>
>> + mutex_unlock(&rdtgroup_mutex);
>> + cpus_read_unlock();
>> + return ret;
>> +}
>> +
>> /* rdtgroup information files for one cache resource. */
>> static struct rftype res_common_files[] = {
>> {
>
> Reinette
>
thanks
Babu
Powered by blists - more mailing lists