Commit 77b66232 authored by Babu Moger's avatar Babu Moger Committed by Borislav Petkov (AMD)
Browse files

fs/resctrl: Introduce interface to display io_alloc CBMs 



Introduce the "io_alloc_cbm" resctrl file to display the capacity bitmasks
(CBMs) that represent the portions of each cache instance allocated
for I/O traffic on a cache resource that supports the "io_alloc" feature.

io_alloc_cbm resides in the info directory of a cache resource, for example,
/sys/fs/resctrl/info/L3/. Since the resource name is part of the path, it
is not necessary to display the resource name as done in the schemata file.

When CDP is enabled, io_alloc routes traffic using the highest CLOSID
associated with the CDP_CODE resource and that CLOSID becomes unusable for
the CDP_DATA resource. The highest CLOSID of CDP_CODE and CDP_DATA resources
will be kept in sync to ensure consistent user interface. In preparation for
this, access the CBMs for I/O traffic through highest CLOSID of either
CDP_CODE or CDP_DATA resource.

Signed-off-by: default avatarBabu Moger <babu.moger@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/55a3ff66a70e7ce8239f022e62b334e9d64af604.1762995456.git.babu.moger@amd.com
parent 9445c705

Documentation/filesystems/resctrl.rst

+19 −0
Original line number Diff line number Diff line
@@ -182,6 +182,25 @@ related to allocation: 
		available for general (CPU) cache allocation for both the CDP_CODE

		and CDP_DATA resources.



"io_alloc_cbm":

		Capacity bitmasks that describe the portions of cache instances to

		which I/O traffic from supported I/O devices are routed when "io_alloc"

		is enabled.



		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



		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

		/sys/fs/resctrl/info/L3CODE/io_alloc_cbm and vice versa.



Memory bandwidth(MB) subdirectory contains the following files

with respect to allocation:

fs/resctrl/ctrlmondata.c

+42 −3
Original line number Diff line number Diff line
@@ -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)

static 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 {
@@ -823,3 +825,40 @@ ssize_t resctrl_io_alloc_write(struct kernfs_open_file *of, char *buf, 


	return ret ?: nbytes;

}



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;

	int ret = 0;



	cpus_read_lock();

	mutex_lock(&rdtgroup_mutex);



	rdt_last_cmd_clear();



	if (!r->cache.io_alloc_capable) {

		rdt_last_cmd_printf("io_alloc is not supported on %s\n", s->name);

		ret = -ENODEV;

		goto out_unlock;

	}



	if (!resctrl_arch_get_io_alloc_enabled(r)) {

		rdt_last_cmd_printf("io_alloc is not enabled on %s\n", s->name);

		ret = -EINVAL;

		goto out_unlock;

	}



	/*

	 * When CDP is enabled, the CBMs of the highest CLOSID of CDP_CODE and

	 * CDP_DATA are kept in sync. As a result, the io_alloc CBMs shown for

	 * either CDP resource are identical and accurately represent the CBMs

	 * used for I/O.

	 */

	show_doms(seq, s, NULL, resctrl_io_alloc_closid(r));



out_unlock:

	mutex_unlock(&rdtgroup_mutex);

	cpus_read_unlock();

	return ret;

}

fs/resctrl/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -438,6 +438,8 @@ ssize_t resctrl_io_alloc_write(struct kernfs_open_file *of, char *buf, 
			       size_t nbytes, loff_t off);



const char *rdtgroup_name_by_closid(u32 closid);

int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of, struct seq_file *seq,

			      void *v);



#ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK

int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);

fs/resctrl/rdtgroup.c

+10 −1
Original line number Diff line number Diff line
@@ -1971,6 +1971,12 @@ 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		= "max_threshold_occupancy",

		.mode		= 0644,
@@ -2171,9 +2177,12 @@ 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_capable) {

		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);

	}

}



void resctrl_file_fflags_init(const char *config, unsigned long fflags)