Hi Reinette, On 6/17/2025 11:03 PM, Reinette Chatre wrote:
Hi Babu, On 6/11/25 2:23 PM, Babu Moger wrote:"io_alloc" feature is a mechanism that enables direct insertion of data""io_alloc" feature is a mechanism that enables" -> ""io_alloc" feature enables"
Sure.
from I/O devices into the L3 cache. By directly caching data from I/ODrop L3
Sure.
devices rather than first storing the I/O data in DRAM, it reduces the demands on DRAM bandwidth and reduces latency to the processor consuming the I/O data. "io_alloc" feature uses the highest CLOSID to route the traffic from I/OHow is the CLOSID related here?
Will remove it.
devices. Provide the interface to modify io_alloc CBMs (Capacity Bit Mask) when feature is enabled. Signed-off-by: Babu Moger <babu.moger@xxxxxxx> ---...--- Documentation/filesystems/resctrl.rst | 13 ++++ fs/resctrl/ctrlmondata.c | 4 +- fs/resctrl/internal.h | 2 + fs/resctrl/rdtgroup.c | 89 ++++++++++++++++++++++++++- 4 files changed, 105 insertions(+), 3 deletions(-) diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst index b31748ec8c61..ae1157dcb4a3 100644 --- a/Documentation/filesystems/resctrl.rst +++ b/Documentation/filesystems/resctrl.rst @@ -181,6 +181,19 @@ related to allocation: # cat /sys/fs/resctrl/info/L3/io_alloc_cbm 0=ffff;1=ffff+ CBM can be configured by writing to the interface.+ + Example:: + + # echo 1=FF > /sys/fs/resctrl/info/L3/io_alloc_cbm + # cat /sys/fs/resctrl/info/L3/io_alloc_cbm + 0=ffff;1=00ff + + When CDP is enabled, io_alloc directs traffic using the highest CLOSID + linked to an L3CODE resource. Although CBMs can be accessed through + either L3CODE or L3DATA resources, any updates to the schemata are + always routed through L3CODE.Please do not commit resctrl to this implementation by documenting it as part of user interface. Could snippet about CDP I shared in patch 6 be placed here as a replacement? Not the usage of *may* to keep implementation options open.
Sure. Yea. Already added in show().
+Memory bandwidth(MB) subdirectory contains the following fileswith respect to allocation: diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c index 6409637b4de6..f3e5e697945c 100644 --- a/fs/resctrl/ctrlmondata.c +++ b/fs/resctrl/ctrlmondata.c @@ -148,8 +148,8 @@ static bool cbm_validate(char *buf, u32 *data, struct rdt_resource *r) * Read one cache bit mask (hex). Check that it is valid for the current * resource type. */ -static int parse_cbm(struct rdt_parse_data *data, struct resctrl_schema *s, - struct rdt_ctrl_domain *d) +int parse_cbm(struct rdt_parse_data *data, struct resctrl_schema *s, + struct rdt_ctrl_domain *d) { enum rdtgrp_mode mode = data->mode; struct resctrl_staged_config *cfg; diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h index 10a3188ffa54..755f23934295 100644 --- a/fs/resctrl/internal.h +++ b/fs/resctrl/internal.h @@ -382,6 +382,8 @@ 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); +int parse_cbm(struct rdt_parse_data *data, struct resctrl_schema *s, + struct rdt_ctrl_domain *d);#ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCKint rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp); diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index 0c2d2cf4baa1..f6c44fae4b72 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -2037,6 +2037,92 @@ static int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of, return ret; }+static int resctrl_io_alloc_parse_line(char *line, struct rdt_resource *r,+ struct resctrl_schema *s, u32 closid) +{ + struct rdt_parse_data data; + struct rdt_ctrl_domain *d; + char *dom = NULL, *id; + unsigned long dom_id; + +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; + } + + dom = strim(dom); + list_for_each_entry(d, &r->ctrl_domains, hdr.list) { + if (d->hdr.id == dom_id) { + data.buf = dom; + data.mode = RDT_MODE_SHAREABLE; + data.closid = closid; + if (parse_cbm(&data, s, d)) + return -EINVAL; + goto next; + } + } + return -EINVAL; +} + +static ssize_t resctrl_io_alloc_cbm_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) +{ + struct resctrl_schema *s = rdt_kn_parent_priv(of->kn); + struct rdt_resource *r = s->res; + u32 io_alloc_closid; + int ret = 0; + + /* Valid input requires a trailing newline */ + if (nbytes == 0 || buf[nbytes - 1] != '\n') + return -EINVAL; + + buf[nbytes - 1] = '\0'; + + if (!r->cache.io_alloc_capable) { + rdt_last_cmd_puts("io_alloc feature is not supported on the resource\n");rdt_last_cmd_puts() requires rdtgroup_mutex to be held.
Sure.
+ return -EINVAL; + } + + cpus_read_lock(); + mutex_lock(&rdtgroup_mutex); + + rdt_last_cmd_clear(); + rdt_staged_configs_clear(); + + if (!resctrl_arch_get_io_alloc_enabled(r)) { + rdt_last_cmd_puts("io_alloc feature is not enabled\n"); + ret = -EINVAL; + goto cbm_write_out;can just be "out"
Sure.
+ } + + io_alloc_closid = resctrl_io_alloc_closid_get(r); + if (io_alloc_closid < 0) {Similar to other places, since this is preceded by resctrl_arch_get_io_alloc_enabled(r) passing the io_alloc_closid has to be valid and can use proposed resctrl_io_alloc_closid() helper to simplify the code.
Yes. Check not required.
+ rdt_last_cmd_puts("Max CLOSID to support io_alloc is not available\n"); + ret = -EINVAL; + goto cbm_write_out; + } + + ret = resctrl_io_alloc_parse_line(buf, r, resctrl_schema_io_alloc(s), + io_alloc_closid);Here too I think both schemata needs to be updated.
Yes. Added it.
+ if (ret) + goto cbm_write_out; + + ret = resctrl_arch_update_domains(r, io_alloc_closid); + +cbm_write_out: + rdt_staged_configs_clear(); + mutex_unlock(&rdtgroup_mutex); + cpus_read_unlock(); + + return ret ?: nbytes; +} + /* rdtgroup information files for one cache resource. */ static struct rftype res_common_files[] = { { @@ -2198,9 +2284,10 @@ static struct rftype res_common_files[] = { }, { .name = "io_alloc_cbm", - .mode = 0444, + .mode = 0644, .kf_ops = &rdtgroup_kf_single_ops, .seq_show = resctrl_io_alloc_cbm_show, + .write = resctrl_io_alloc_cbm_write, }, { .name = "mba_MBps_event",Reinette
Thanks Babu
