linux-kernel - Re: [PATCH v5 06/14] perf bench mem: Allow mapping of hugepages

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Message-ID: <aHa2HHWaShp-Vk4m@google.com>
Date: Tue, 15 Jul 2025 13:12:12 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ankur Arora <ankur.a.arora@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
	akpm@...ux-foundation.org, david@...hat.com, bp@...en8.de,
	dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
	mjguzik@...il.com, luto@...nel.org, peterz@...radead.org,
	acme@...nel.org, tglx@...utronix.de, willy@...radead.org,
	raghavendra.kt@....com, boris.ostrovsky@...cle.com,
	konrad.wilk@...cle.com
Subject: Re: [PATCH v5 06/14] perf bench mem: Allow mapping of hugepages

On Wed, Jul 09, 2025 at 05:59:18PM -0700, Ankur Arora wrote:
> Page sizes that can be selected: 4KB, 2MB, 1GB.
> 
> Both the reservation and node from which hugepages are allocated
> from are expected to be addressed by the user.

It'd be nice if you could provide an example in the commit message when
you introduce a new command line option.  Also please update
Documentation/perf-bench.txt.

Thanks,
Namhyung

> 
> Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
> ---
>  tools/perf/bench/mem-functions.c | 33 ++++++++++++++++++++++++++++----
>  1 file changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/bench/mem-functions.c b/tools/perf/bench/mem-functions.c
> index 914f9048d982..e4d713587d45 100644
> --- a/tools/perf/bench/mem-functions.c
> +++ b/tools/perf/bench/mem-functions.c
> @@ -25,11 +25,17 @@
>  #include <sys/mman.h>
>  #include <errno.h>
>  #include <linux/time64.h>
> +#include <linux/log2.h>
>  
>  #define K 1024
>  
> +#define PAGE_SHIFT_4KB		12
> +#define PAGE_SHIFT_2MB		21
> +#define PAGE_SHIFT_1GB		30
> +
>  static const char	*size_str	= "1MB";
>  static const char	*function_str	= "all";
> +static const char	*page_size_str	= "4KB";
>  static unsigned int	nr_loops	= 1;
>  static bool		use_cycles;
>  static int		cycles_fd;
> @@ -39,6 +45,10 @@ static const struct option options[] = {
>  		    "Specify the size of the memory buffers. "
>  		    "Available units: B, KB, MB, GB and TB (case insensitive)"),
>  
> +	OPT_STRING('p', "page", &page_size_str, "4KB",
> +		    "Specify page-size for mapping memory buffers. "
> +		    "Available sizes: 4KB, 2MB, 1GB (case insensitive)"),
> +
>  	OPT_STRING('f', "function", &function_str, "all",
>  		    "Specify the function to run, \"all\" runs all available functions, \"help\" lists them"),
>  
> @@ -60,6 +70,7 @@ struct bench_params {
>  	size_t		size;
>  	size_t		size_total;
>  	unsigned int	nr_loops;
> +	unsigned int	page_shift;
>  };
>  
>  struct bench_mem_info {
> @@ -202,7 +213,8 @@ static void __bench_mem_function(struct bench_mem_info *info, struct bench_param
>  	if (r->fn.fini) r->fn.fini(info, p, &src, &dst);
>  	return;
>  out_init_failed:
> -	printf("# Memory allocation failed - maybe size (%s) is too large?\n", size_str);
> +	printf("# Memory allocation failed - maybe size (%s) %s?\n", size_str,
> +			p->page_shift != PAGE_SHIFT_4KB ? "has insufficient hugepages" : "is too large");
>  	goto out_free;
>  }
>  
> @@ -210,6 +222,7 @@ static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *
>  {
>  	int i;
>  	struct bench_params p = { 0 };
> +	unsigned int page_size;
>  
>  	argc = parse_options(argc, argv, options, info->usage, 0);
>  
> @@ -229,6 +242,15 @@ static int bench_mem_common(int argc, const char **argv, struct bench_mem_info *
>  	}
>  	p.size_total = (size_t)p.size * p.nr_loops;
>  
> +	page_size = (unsigned int)perf_atoll((char *)page_size_str);
> +	if (page_size != (1 << PAGE_SHIFT_4KB) &&
> +	    page_size != (1 << PAGE_SHIFT_2MB) &&
> +	    page_size != (1 << PAGE_SHIFT_1GB)) {
> +		fprintf(stderr, "Invalid page-size:%s\n", page_size_str);
> +		return 1;
> +	}
> +	p.page_shift = ilog2(page_size);
> +
>  	if (!strncmp(function_str, "all", 3)) {
>  		for (i = 0; info->functions[i].name; i++)
>  			__bench_mem_function(info, &p, i);
> @@ -285,11 +307,14 @@ static int do_memcpy(const struct function *r, struct bench_params *p,
>  	return 0;
>  }
>  
> -static void *bench_mmap(size_t size, bool populate)
> +static void *bench_mmap(size_t size, bool populate, unsigned int page_shift)
>  {
>  	void *p;
>  	int extra = populate ? MAP_POPULATE : 0;
>  
> +	if (page_shift != PAGE_SHIFT_4KB)
> +		extra |= MAP_HUGETLB | (page_shift << MAP_HUGE_SHIFT);
> +
>  	p = mmap(NULL, size, PROT_READ|PROT_WRITE,
>  		 extra | MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
>  
> @@ -307,11 +332,11 @@ static bool mem_alloc(struct bench_mem_info *info, struct bench_params *p,
>  {
>  	bool failed;
>  
> -	*dst = bench_mmap(p->size, true);
> +	*dst = bench_mmap(p->size, true, p->page_shift);
>  	failed = *dst == NULL;
>  
>  	if (info->alloc_src) {
> -		*src = bench_mmap(p->size, true);
> +		*src = bench_mmap(p->size, true, p->page_shift);
>  		failed = failed || *src == NULL;
>  	}
>  
> -- 
> 2.43.5
>