Messages in this thread Patch in this message |  | | Date | Fri, 5 Dec 2025 13:30:09 -0600 | | Subject | Re: [PATCH 3/3] x86/resctrl: Add "*" shorthand to set minimum io_alloc CBM for all domains | | From | "Moger, Babu" <> |
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Hi Aaron,
On 11/26/2025 11:16 AM, Aaron Tomlin wrote: > This patch introduces a special domain ID selector "*" for io_alloc_cbm > that allows setting the CBM of each cache domain to its minimum number > of consecutive bits in a single operation. For example, writing "*=0" to > /sys/fs/resctrl/info/L3/io_alloc_cbm programs each domain's CBM to the > hardware-defined minimum, greatly simplifying automation and management > tasks. The user is required to specify the correct minimum stored in > /sys/fs/resctrl/info/L3/min_cbm_bits. > > Signed-off-by: Aaron Tomlin <atomlin@atomlin.com> > --- > Documentation/filesystems/resctrl.rst | 10 ++ > arch/x86/kernel/cpu/resctrl/core.c | 2 +- > arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 23 +++-- > fs/resctrl/ctrlmondata.c | 108 +++++++++++++++++----- > fs/resctrl/internal.h | 13 +++ > fs/resctrl/rdtgroup.c | 2 +- > include/linux/resctrl.h | 30 +++++- > 7 files changed, 155 insertions(+), 33 deletions(-) > > diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst > index 8c8ce678148a..9c128c8fba86 100644 > --- a/Documentation/filesystems/resctrl.rst > +++ b/Documentation/filesystems/resctrl.rst > @@ -215,6 +215,16 @@ related to allocation: > # cat /sys/fs/resctrl/info/L3/io_alloc_cbm > 0=00ff;1=000f > > + Set each CBM to their minimum number of consecutive bits. > + > + A special value "*" is required to represent all cache IDs. > + The user should specify the correct minimum stored in > + /sys/fs/resctrl/info/L3/min_cbm_bits. > + > + Example:: > + > + # echo "*=0" > /sys/fs/resctrl/info/L3/io_alloc_cbm > + > When CDP is enabled "io_alloc_cbm" associated with the CDP_DATA and CDP_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 > diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c > index 3792ab4819dc..44aea6b534e0 100644 > --- a/arch/x86/kernel/cpu/resctrl/core.c > +++ b/arch/x86/kernel/cpu/resctrl/core.c > @@ -276,7 +276,7 @@ static void rdt_get_cdp_config(int level) > > static void rdt_set_io_alloc_capable(struct rdt_resource *r) > { > - r->cache.io_alloc_capable = true; > + r->cache.io_alloc.io_alloc_capable = true; > } > > 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 b20e705606b8..0f051d848422 100644 > --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c > @@ -57,14 +57,19 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid) > hw_dom = resctrl_to_arch_ctrl_dom(d); > msr_param.res = NULL; > for (t = 0; t < CDP_NUM_TYPES; t++) { > - cfg = &hw_dom->d_resctrl.staged_config[t]; > - if (!cfg->have_new_ctrl) > - continue; > - > - idx = resctrl_get_config_index(closid, t); > - if (cfg->new_ctrl == hw_dom->ctrl_val[idx]) > - continue; > - hw_dom->ctrl_val[idx] = cfg->new_ctrl; > + if (resctrl_should_io_alloc_min_cbm(r)) { > + idx = resctrl_get_config_index(closid, t); > + hw_dom->ctrl_val[idx] = apply_io_alloc_min_cbm(r); > + } else { > + cfg = &hw_dom->d_resctrl.staged_config[t]; > + if (!cfg->have_new_ctrl) > + continue; > + > + idx = resctrl_get_config_index(closid, t); > + if (cfg->new_ctrl == hw_dom->ctrl_val[idx]) > + continue; > + hw_dom->ctrl_val[idx] = cfg->new_ctrl; > + } > > if (!msr_param.res) { > msr_param.low = idx; > @@ -123,7 +128,7 @@ int resctrl_arch_io_alloc_enable(struct rdt_resource *r, bool enable) > { > struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r); > > - if (hw_res->r_resctrl.cache.io_alloc_capable && > + if (hw_res->r_resctrl.cache.io_alloc.io_alloc_capable && > hw_res->sdciae_enabled != enable) { > _resctrl_sdciae_enable(r, enable); > hw_res->sdciae_enabled = enable; > diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c > index 5f6f96d70e4a..b3abd781899f 100644 > --- a/fs/resctrl/ctrlmondata.c > +++ b/fs/resctrl/ctrlmondata.c > @@ -688,7 +688,7 @@ int resctrl_io_alloc_show(struct kernfs_open_file *of, struct seq_file *seq, voi > > mutex_lock(&rdtgroup_mutex); > > - if (r->cache.io_alloc_capable) { > + if (r->cache.io_alloc.io_alloc_capable) { > if (resctrl_arch_get_io_alloc_enabled(r)) > seq_puts(seq, "enabled\n"); > else > @@ -712,13 +712,31 @@ static bool resctrl_io_alloc_closid_supported(u32 io_alloc_closid) > return io_alloc_closid < closids_supported(); > } > > +/** > + * resctrl_sync_cdp_peer - Mirror staged configuration to the CDP peer type > + * > + * @s: resctrl schema > + * @d: resctrl control domain > + * > + * The caller must ensure CDP is enabled for the resource and must be > + * called under the cpu hotplug lock and rdtgroup mutex > + */ > +static void resctrl_sync_cdp_peer(struct resctrl_schema *s, struct rdt_ctrl_domain *d) > +{ > + enum resctrl_conf_type peer_type; > + > + peer_type = resctrl_peer_type(s->conf_type); > + memcpy(&d->staged_config[peer_type], > + &d->staged_config[s->conf_type], > + sizeof(d->staged_config[0])); > +} > + > /* > * Initialize io_alloc CLOSID cache resource CBM with all usable (shared > * and unused) cache portions. > */ > static int resctrl_io_alloc_init_cbm(struct resctrl_schema *s, u32 closid) > { > - enum resctrl_conf_type peer_type; > struct rdt_resource *r = s->res; > struct rdt_ctrl_domain *d; > int ret; > @@ -731,11 +749,8 @@ static int resctrl_io_alloc_init_cbm(struct resctrl_schema *s, u32 closid) > > /* Keep CDP_CODE and CDP_DATA of io_alloc CLOSID's CBM in sync. */ > if (resctrl_arch_get_cdp_enabled(r->rid)) { > - peer_type = resctrl_peer_type(s->conf_type); > list_for_each_entry(d, &s->res->ctrl_domains, hdr.list) > - memcpy(&d->staged_config[peer_type], > - &d->staged_config[s->conf_type], > - sizeof(d->staged_config[0])); > + resctrl_sync_cdp_peer(s, d); > } > > ret = resctrl_arch_update_domains(r, closid); > @@ -903,29 +918,82 @@ int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of, struct seq_file *seq, > return ret; > } > > +/** > + * parse_domain_cbm - Parse "domain=cbm" and return either side > + * > + * @line_ptr: Pointer to the input string > + * @out_val: Output from parsed value (either domain ID or CDM) > + * @which: Selector for which side to parse > + * > + * It is assumed that *line_ptr and *out_val are valid. > + * > + * Return: 0 on success and advance *line_ptr to point past the > + * delimiter, EINVAL on parsing error > + */ > +static int parse_domain_cbm(char **line_ptr, unsigned long *out_val, > + enum resctrl_kv_sel which) > +{ > + char *rhs, *lhs, *tok; > + unsigned int base; > + > + rhs = *line_ptr; > + > + lhs = strsep(&rhs, "="); > + if (!lhs || !rhs) > + goto err; > + > + if (which == RDT_PARSE_DOMAIN) { > + tok = lhs; > + base = 10; > + } else { > + tok = rhs; > + base = 16; > + } > + tok = strim(tok); > + > + if (kstrtoul(tok, base, out_val)) > + goto err; > + > + *line_ptr = rhs; > + return 0; > +err: > + rdt_last_cmd_puts("Invalid domain=cbm: missing '=' or non-numeric value\n"); > + return -EINVAL; > +} > + > static int resctrl_io_alloc_parse_line(char *line, struct rdt_resource *r, > struct resctrl_schema *s, u32 closid) > { > - enum resctrl_conf_type peer_type; > struct rdt_parse_data data; > struct rdt_ctrl_domain *d; > - char *dom = NULL, *id; > - unsigned long dom_id; > + char *dom = NULL; > + unsigned long out_val; > + int ret; > + > + if (line[0] == '*') { > + ret = parse_domain_cbm(&line, &out_val, RDT_PARSE_CBM); > + if (ret) > + return ret; > > + if (out_val == r->cache.min_cbm_bits) { > + r->cache.io_alloc.io_alloc_min_cbm = true; > + return 0; > + } > + rdt_last_cmd_puts("Invalid io_alloc min CBM\n"); > + return -EINVAL; > + } > next: > if (!line || line[0] == '\0') > return 0; > > dom = strsep(&line, ";"); > - id = strsep(&dom, "="); > - if (!dom || kstrtoul(id, 10, &dom_id)) { > - rdt_last_cmd_puts("Missing '=' or non-numeric domain\n"); > - return -EINVAL; > - } > + ret = parse_domain_cbm(&line, &out_val, RDT_PARSE_DOMAIN); > + if (ret) > + return ret; >
I feel this the lot of changes to take care of one extra character change. I feel code can be simplified to just this function.
id = strim(id); dom = strim(dom);
if (!strcmp(id, "*")) all = true; else if (kstrtoul(id, 10, &dom_id)) { rdt_last_cmd_puts("Non-numeric domain\n"); return -EINVAL; }
data.buf = dom; data.mode = RDT_MODE_SHAREABLE; data.closid = closid;
if (all) apply the CBMs to all the doamins. else Apply the CBMs to just one domain.
Any problems with this approach?
Thanks
Babu
> dom = strim(dom); > list_for_each_entry(d, &r->ctrl_domains, hdr.list) { > - if (d->hdr.id == dom_id) { > + if (d->hdr.id == out_val) { > data.buf = dom; > data.mode = RDT_MODE_SHAREABLE; > data.closid = closid; > @@ -935,12 +1003,8 @@ static int resctrl_io_alloc_parse_line(char *line, struct rdt_resource *r, > * Keep io_alloc CLOSID's CBM of CDP_CODE and CDP_DATA > * in sync. > */ > - if (resctrl_arch_get_cdp_enabled(r->rid)) { > - peer_type = resctrl_peer_type(s->conf_type); > - memcpy(&d->staged_config[peer_type], > - &d->staged_config[s->conf_type], > - sizeof(d->staged_config[0])); > - } > + if (resctrl_arch_get_cdp_enabled(r->rid)) > + resctrl_sync_cdp_peer(s, d); > goto next; > } > } > @@ -982,6 +1046,8 @@ ssize_t resctrl_io_alloc_cbm_write(struct kernfs_open_file *of, char *buf, > goto out_clear_configs; > > ret = resctrl_arch_update_domains(r, io_alloc_closid); > + if (resctrl_should_io_alloc_min_cbm(r)) > + r->cache.io_alloc.io_alloc_min_cbm = false; > > out_clear_configs: > rdt_staged_configs_clear(); > diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h > index bff4a54ae333..3846737992bb 100644 > --- a/fs/resctrl/internal.h > +++ b/fs/resctrl/internal.h > @@ -143,6 +143,19 @@ enum rdt_group_type { > RDT_NUM_GROUP, > }; > > +/** > + * enum resctrl_kv_sel - Selector for "domain=cbm" key/value parsing > + * @RDT_PARSE_DOMAIN: Parse the left-hand side (domain ID) > + * @RDT_PARSE_CBM: Parse the right-hand side (CBM value) > + * > + * Used by parsers of key/value pairs formatted as "domain=cbm" to indicate > + * which token should be extracted and converted. > + */ > +enum resctrl_kv_sel { > + RDT_PARSE_DOMAIN, > + RDT_PARSE_CBM, > +}; > + > /** > * enum rdtgrp_mode - Mode of a RDT resource group > * @RDT_MODE_SHAREABLE: This resource group allows sharing of its allocations > diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c > index e1dc63b2218f..83ce3bafa5cb 100644 > --- a/fs/resctrl/rdtgroup.c > +++ b/fs/resctrl/rdtgroup.c > @@ -2196,7 +2196,7 @@ static void io_alloc_init(void) > { > struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3); > > - if (r->cache.io_alloc_capable) { > + if (r->cache.io_alloc.io_alloc_capable) { > resctrl_file_fflags_init("io_alloc", RFTYPE_CTRL_INFO | > RFTYPE_RES_CACHE); > resctrl_file_fflags_init("io_alloc_cbm", > diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h > index 54701668b3df..9e75959565dc 100644 > --- a/include/linux/resctrl.h > +++ b/include/linux/resctrl.h > @@ -215,7 +215,10 @@ struct resctrl_cache { > unsigned int shareable_bits; > bool arch_has_sparse_bitmasks; > bool arch_has_per_cpu_cfg; > - bool io_alloc_capable; > + struct { > + bool io_alloc_capable; > + bool io_alloc_min_cbm; > + } io_alloc; > }; > > /** > @@ -415,6 +418,31 @@ static inline bool resctrl_is_mbm_event(enum resctrl_event_id eventid) > eventid <= QOS_L3_MBM_LOCAL_EVENT_ID); > } > > +/** > + * apply_io_alloc_min_cbm() - Apply minimum io_alloc CBM > + * > + * @r: resctrl resource > + * > + * Return: Minimum number of consecutive io_alloc CBM bits to be set. > + */ > +static inline u32 apply_io_alloc_min_cbm(struct rdt_resource *r) > +{ > + return r->cache.min_cbm_bits; > +} > + > +/** > + * resctrl_should_io_alloc_min_cbm() - Should the minimum io_alloc > + * CBM be applied > + * @r: resctrl resource > + * > + * Return: True if the minimum number of consecutive > + * bits to be set in the io_alloc CBM should be applied. > + */ > +static inline bool resctrl_should_io_alloc_min_cbm(struct rdt_resource *r) > +{ > + return r->cache.io_alloc.io_alloc_min_cbm; > +} > + > u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id eventid); > > /* Iterate over all memory bandwidth events */
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