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x86/resctrl: Add write option to "mba_MBps_event" file

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The "mba_MBps" mount option provides an alternate method to control memory
bandwidth. Instead of specifying allowable bandwidth as a percentage of
maximum possible, the user provides a MiB/s limit value.

There is a file in each CTRL_MON group directory that shows the event
currently in use.

Allow writing that file to choose a different event.

A user can choose any of the memory bandwidth monitoring events listed in
/sys/fs/resctrl/info/L3_mon/mon_features independently for each CTRL_MON group
by writing to each of the "mba_MBps_event" files.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20241206163148.83828-8-tony.luck@intel.com
This commit is contained in:
Tony Luck 2024-12-06 08:31:47 -08:00 committed by Borislav Petkov (AMD)
parent f5cd0e316f
commit 8e931105ac
3 changed files with 44 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
arch/x86/kernel/cpu/resctrl/ctrlmondata.c
View File

@ -518,6 +518,46 @@ static int smp_mon_event_count(void *arg)
return 0;
}
ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct rdtgroup *rdtgrp;
int ret = 0;
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n')
return -EINVAL;
buf[nbytes - 1] = '\0';
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
rdt_last_cmd_clear();
if (!strcmp(buf, "mbm_local_bytes")) {
if (is_mbm_local_enabled())
rdtgrp->mba_mbps_event = QOS_L3_MBM_LOCAL_EVENT_ID;
else
ret = -EINVAL;
} else if (!strcmp(buf, "mbm_total_bytes")) {
if (is_mbm_total_enabled())
rdtgrp->mba_mbps_event = QOS_L3_MBM_TOTAL_EVENT_ID;
else
ret = -EINVAL;
} else {
ret = -EINVAL;
}
if (ret)
rdt_last_cmd_printf("Unsupported event id '%s'\n", buf);
rdtgroup_kn_unlock(of->kn);
return ret ?: nbytes;
}
int rdtgroup_mba_mbps_event_show(struct kernfs_open_file *of,
struct seq_file *s, void *v)
{

2
arch/x86/kernel/cpu/resctrl/internal.h
View File

@ -610,6 +610,8 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off);
int rdtgroup_schemata_show(struct kernfs_open_file *of,
struct seq_file *s, void *v);
ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off);
int rdtgroup_mba_mbps_event_show(struct kernfs_open_file *of,
struct seq_file *s, void *v);
bool rdtgroup_cbm_overlaps(struct resctrl_schema *s, struct rdt_ctrl_domain *d,

3
arch/x86/kernel/cpu/resctrl/rdtgroup.c
View File

@ -1952,8 +1952,9 @@ static struct rftype res_common_files[] = {
},
{
.name = "mba_MBps_event",
.mode = 0444,
.mode = 0644,
.kf_ops = &rdtgroup_kf_single_ops,
.write = rdtgroup_mba_mbps_event_write,
.seq_show = rdtgroup_mba_mbps_event_show,
},
{