Commit f58dc01b authored by Tejun Heo's avatar Tejun Heo
Browse files

percpu: generalize first chunk allocator selection 



Now that all first chunk allocators are in mm/percpu.c, it makes sense
to make generalize percpu_alloc kernel parameter.  Define PCPU_FC_*
and set pcpu_chosen_fc using early_param() in mm/percpu.c.  Arch code
can use the set value to determine which first chunk allocator to use.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 08fc4580

Documentation/kernel-parameters.txt

+6 −5
Original line number Diff line number Diff line
@@ -1919,11 +1919,12 @@ and is between 256 and 4096 characters. It is defined in the file 
			Format: { 0 | 1 }

			See arch/parisc/kernel/pdc_chassis.c



	percpu_alloc=	[X86] Select which percpu first chunk allocator to use.

			Allowed values are one of "lpage", "embed" and "page".

			See comments in arch/x86/kernel/setup_percpu.c for

			details on each allocator.  This parameter is primarily

			for debugging and performance comparison.

	percpu_alloc=	Select which percpu first chunk allocator to use.

			Currently supported values are "embed", "page" and

			"lpage".  Archs may support subset or none of the

			selections.  See comments in mm/percpu.c for details

			on each allocator.  This parameter is primarily	for

			debugging and performance comparison.



	pf.		[PARIDE]

			See Documentation/blockdev/paride.txt.

arch/x86/kernel/setup_percpu.c

+6 −18
Original line number Diff line number Diff line
@@ -267,16 +267,6 @@ static ssize_t __init setup_pcpu_page(size_t static_size) 
				     pcpup_populate_pte);

}



/* for explicit first chunk allocator selection */

static char pcpu_chosen_alloc[16] __initdata;



static int __init percpu_alloc_setup(char *str)

{

	strncpy(pcpu_chosen_alloc, str, sizeof(pcpu_chosen_alloc) - 1);

	return 0;

}

early_param("percpu_alloc", percpu_alloc_setup);



static inline void setup_percpu_segment(int cpu)

{

#ifdef CONFIG_X86_32
@@ -307,19 +297,17 @@ void __init setup_per_cpu_areas(void) 
	 * each allocator for details.

	 */

	ret = -EINVAL;

	if (strlen(pcpu_chosen_alloc)) {

		if (strcmp(pcpu_chosen_alloc, "page")) {

			if (!strcmp(pcpu_chosen_alloc, "lpage"))

	if (pcpu_chosen_fc != PCPU_FC_AUTO) {

		if (pcpu_chosen_fc != PCPU_FC_PAGE) {

			if (pcpu_chosen_fc == PCPU_FC_LPAGE)

				ret = setup_pcpu_lpage(static_size, true);

			else if (!strcmp(pcpu_chosen_alloc, "embed"))

				ret = setup_pcpu_embed(static_size, true);

			else

				pr_warning("PERCPU: unknown allocator %s "

					   "specified\n", pcpu_chosen_alloc);

				ret = setup_pcpu_embed(static_size, true);



			if (ret < 0)

				pr_warning("PERCPU: %s allocator failed (%zd), "

					   "falling back to page size\n",

					   pcpu_chosen_alloc, ret);

					   pcpu_fc_names[pcpu_chosen_fc], ret);

		}

	} else {

		ret = setup_pcpu_lpage(static_size, false);

include/linux/percpu.h

+12 −0
Original line number Diff line number Diff line
@@ -59,6 +59,18 @@ 
extern void *pcpu_base_addr;

extern const int *pcpu_unit_map;



enum pcpu_fc {

	PCPU_FC_AUTO,

	PCPU_FC_EMBED,

	PCPU_FC_PAGE,

	PCPU_FC_LPAGE,



	PCPU_FC_NR,

};

extern const char *pcpu_fc_names[PCPU_FC_NR];



extern enum pcpu_fc pcpu_chosen_fc;



typedef void * (*pcpu_fc_alloc_fn_t)(unsigned int cpu, size_t size);

typedef void (*pcpu_fc_free_fn_t)(void *ptr, size_t size);

typedef void (*pcpu_fc_populate_pte_fn_t)(unsigned long addr);

mm/percpu.c

+32 −0
Original line number Diff line number Diff line
@@ -1414,6 +1414,38 @@ size_t __init pcpu_setup_first_chunk(size_t static_size, size_t reserved_size, 
	return pcpu_unit_size;

}



const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {

	[PCPU_FC_AUTO]	= "auto",

	[PCPU_FC_EMBED]	= "embed",

	[PCPU_FC_PAGE]	= "page",

	[PCPU_FC_LPAGE]	= "lpage",

};



enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;



static int __init percpu_alloc_setup(char *str)

{

	if (0)

		/* nada */;

#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK

	else if (!strcmp(str, "embed"))

		pcpu_chosen_fc = PCPU_FC_EMBED;

#endif

#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK

	else if (!strcmp(str, "page"))

		pcpu_chosen_fc = PCPU_FC_PAGE;

#endif

#ifdef CONFIG_NEED_PER_CPU_LPAGE_FIRST_CHUNK

	else if (!strcmp(str, "lpage"))

		pcpu_chosen_fc = PCPU_FC_LPAGE;

#endif

	else

		pr_warning("PERCPU: unknown allocator %s specified\n", str);



	return 0;

}

early_param("percpu_alloc", percpu_alloc_setup);



static inline size_t pcpu_calc_fc_sizes(size_t static_size,

					size_t reserved_size,

					ssize_t *dyn_sizep)

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