Commit 3a6bf92b authored by Huang Ying's avatar Huang Ying Committed by Ze Zuo
Browse files

cacheinfo: calculate size of per-CPU data cache slice 

mainline inclusion
from mainline-v6.7-rc1
commit 94a3bfe4073cd88b05f7fb201ea7bf9dfa2cf5d5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8JXIR

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=94a3bfe4073cd88b05f7fb201ea7bf9dfa2cf5d5

--------------------------------

This can be used to estimate the size of the data cache slice that can be
used by one CPU under ideal circumstances.  Both DATA caches and UNIFIED
caches are used in calculation.  So, the users need to consider the impact
of the code cache usage.

Because the cache inclusive/non-inclusive information isn't available now,
we just use the size of the per-CPU slice of LLC to make the result more
predictable across architectures.  This may be improved when more cache
information is available in the future.

A brute-force algorithm to iterate all online CPUs is used to avoid to
allocate an extra cpumask, especially in offline callback.

Link: https://lkml.kernel.org/r/20231016053002.756205-3-ying.huang@intel.com


Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Acked-by: default avatarMel Gorman <mgorman@techsingularity.net>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarZe Zuo <zuoze1@huawei.com>
parent d6073fed

drivers/base/cacheinfo.c

+48 −1
Original line number Diff line number Diff line
@@ -898,6 +898,48 @@ static int cache_add_dev(unsigned int cpu) 
	return rc;

}



/*

 * Calculate the size of the per-CPU data cache slice.  This can be

 * used to estimate the size of the data cache slice that can be used

 * by one CPU under ideal circumstances.  UNIFIED caches are counted

 * in addition to DATA caches.  So, please consider code cache usage

 * when use the result.

 *

 * Because the cache inclusive/non-inclusive information isn't

 * available, we just use the size of the per-CPU slice of LLC to make

 * the result more predictable across architectures.

 */

static void update_per_cpu_data_slice_size_cpu(unsigned int cpu)

{

	struct cpu_cacheinfo *ci;

	struct cacheinfo *llc;

	unsigned int nr_shared;



	if (!last_level_cache_is_valid(cpu))

		return;



	ci = ci_cacheinfo(cpu);

	llc = per_cpu_cacheinfo_idx(cpu, cache_leaves(cpu) - 1);



	if (llc->type != CACHE_TYPE_DATA && llc->type != CACHE_TYPE_UNIFIED)

		return;



	nr_shared = cpumask_weight(&llc->shared_cpu_map);

	if (nr_shared)

		ci->per_cpu_data_slice_size = llc->size / nr_shared;

}



static void update_per_cpu_data_slice_size(bool cpu_online, unsigned int cpu)

{

	unsigned int icpu;



	for_each_online_cpu(icpu) {

		if (!cpu_online && icpu == cpu)

			continue;

		update_per_cpu_data_slice_size_cpu(icpu);

	}

}



static int cacheinfo_cpu_online(unsigned int cpu)

{

	int rc = detect_cache_attributes(cpu);
@@ -906,6 +948,10 @@ static int cacheinfo_cpu_online(unsigned int cpu) 
		return rc;

	rc = cache_add_dev(cpu);

	if (rc)

		goto err;

	update_per_cpu_data_slice_size(true, cpu);

	return 0;

err:

	free_cache_attributes(cpu);

	return rc;

}
@@ -916,6 +962,7 @@ static int cacheinfo_cpu_pre_down(unsigned int cpu) 
		cpu_cache_sysfs_exit(cpu);



	free_cache_attributes(cpu);

	update_per_cpu_data_slice_size(false, cpu);

	return 0;

}

include/linux/cacheinfo.h

+1 −0
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ struct cacheinfo { 


struct cpu_cacheinfo {

	struct cacheinfo *info_list;

	unsigned int per_cpu_data_slice_size;

	unsigned int num_levels;

	unsigned int num_leaves;

	bool cpu_map_populated;