Commit 83919535 authored by David Hildenbrand's avatar David Hildenbrand Committed by Linus Torvalds
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mm/shuffle: remove dynamic reconfiguration 

Commit e900a918 ("mm: shuffle initial free memory to improve
memory-side-cache utilization") promised "autodetection of a
memory-side-cache (to be added in a follow-on patch)" over a year ago.

The original series included patches [1], however, they were dropped
during review [2] to be followed-up later.

Due to lack of platforms that publish an HMAT, autodetection is currently
not implemented.  However, manual activation is actively used [3].  Let's
simplify for now and re-add when really (ever?) needed.

[1] https://lkml.kernel.org/r/154510700291.1941238.817190985966612531.stgit@dwillia2-desk3.amr.corp.intel.com
[2] https://lkml.kernel.org/r/154690326478.676627.103843791978176914.stgit@dwillia2-desk3.amr.corp.intel.com
[3] https://lkml.kernel.org/r/CAPcyv4irwGUU2x+c6b4L=KbB1dnasNKaaZd6oSpYjL9kfsnROQ@mail.gmail.com



Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarWei Yang <richard.weiyang@linux.alibaba.com>
Acked-by: default avatarDan Williams <dan.j.williams@intel.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Link: http://lkml.kernel.org/r/20200624094741.9918-4-david@redhat.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 93146d98

mm/shuffle.c

+2 −26
Original line number Diff line number Diff line
@@ -10,33 +10,11 @@ 
#include "shuffle.h"



DEFINE_STATIC_KEY_FALSE(page_alloc_shuffle_key);

static unsigned long shuffle_state __ro_after_init;



/*

 * Depending on the architecture, module parameter parsing may run

 * before, or after the cache detection. SHUFFLE_FORCE_DISABLE prevents,

 * or reverts the enabling of the shuffle implementation. SHUFFLE_ENABLE

 * attempts to turn on the implementation, but aborts if it finds

 * SHUFFLE_FORCE_DISABLE already set.

 */

__meminit void page_alloc_shuffle(enum mm_shuffle_ctl ctl)

{

	if (ctl == SHUFFLE_FORCE_DISABLE)

		set_bit(SHUFFLE_FORCE_DISABLE, &shuffle_state);



	if (test_bit(SHUFFLE_FORCE_DISABLE, &shuffle_state)) {

		if (test_and_clear_bit(SHUFFLE_ENABLE, &shuffle_state))

			static_branch_disable(&page_alloc_shuffle_key);

	} else if (ctl == SHUFFLE_ENABLE

			&& !test_and_set_bit(SHUFFLE_ENABLE, &shuffle_state))

		static_branch_enable(&page_alloc_shuffle_key);

}



static bool shuffle_param;

static int shuffle_show(char *buffer, const struct kernel_param *kp)

{

	return sprintf(buffer, "%c\n", test_bit(SHUFFLE_ENABLE, &shuffle_state)

			? 'Y' : 'N');

	return sprintf(buffer, "%c\n", shuffle_param ? 'Y' : 'N');

}



static __meminit int shuffle_store(const char *val,
@@ -47,9 +25,7 @@ static __meminit int shuffle_store(const char *val, 
	if (rc < 0)

		return rc;

	if (shuffle_param)

		page_alloc_shuffle(SHUFFLE_ENABLE);

	else

		page_alloc_shuffle(SHUFFLE_FORCE_DISABLE);

		static_branch_enable(&page_alloc_shuffle_key);

	return 0;

}

module_param_call(shuffle, shuffle_store, shuffle_show, &shuffle_param, 0400);

mm/shuffle.h

+0 −17
Original line number Diff line number Diff line
@@ -4,23 +4,10 @@ 
#define _MM_SHUFFLE_H

#include <linux/jump_label.h>



/*

 * SHUFFLE_ENABLE is called from the command line enabling path, or by

 * platform-firmware enabling that indicates the presence of a

 * direct-mapped memory-side-cache. SHUFFLE_FORCE_DISABLE is called from

 * the command line path and overrides any previous or future

 * SHUFFLE_ENABLE.

 */

enum mm_shuffle_ctl {

	SHUFFLE_ENABLE,

	SHUFFLE_FORCE_DISABLE,

};



#define SHUFFLE_ORDER (MAX_ORDER-1)



#ifdef CONFIG_SHUFFLE_PAGE_ALLOCATOR

DECLARE_STATIC_KEY_FALSE(page_alloc_shuffle_key);

extern void page_alloc_shuffle(enum mm_shuffle_ctl ctl);

extern void __shuffle_free_memory(pg_data_t *pgdat);

extern bool shuffle_pick_tail(void);

static inline void shuffle_free_memory(pg_data_t *pgdat)
@@ -58,10 +45,6 @@ static inline void shuffle_zone(struct zone *z) 
{

}



static inline void page_alloc_shuffle(enum mm_shuffle_ctl ctl)

{

}



static inline bool is_shuffle_order(int order)

{

	return false;

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