linux-kernel - Re: [RFC v2 5/5] ktest: sys_move_phys

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Message-ID: <20231002150924.00006a7b@Huawei.com>
Date:   Mon, 2 Oct 2023 15:09:24 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Gregory Price <gourry.memverge@...il.com>
CC:     <linux-mm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arch@...r.kernel.org>, <linux-api@...r.kernel.org>,
        <linux-cxl@...r.kernel.org>, <luto@...nel.org>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <dave.hansen@...ux.intel.com>, <hpa@...or.com>, <arnd@...db.de>,
        <akpm@...ux-foundation.org>, <x86@...nel.org>,
        Gregory Price <gregory.price@...verge.com>
Subject: Re: [RFC v2 5/5] ktest: sys_move_phys_pages ktest

On Tue, 19 Sep 2023 19:09:08 -0400
Gregory Price <gourry.memverge@...il.com> wrote:

> Implement simple ktest that looks up the physical address via
> /proc/self/pagemap and migrates the page based on that information.
> 
> Signed-off-by: Gregory Price <gregory.price@...verge.com>

One trivial comment inline.


> ---
>  tools/testing/selftests/mm/migration.c | 101 +++++++++++++++++++++++++
>  1 file changed, 101 insertions(+)
> 
> diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c
> index 6908569ef406..67fbae243f94 100644
> --- a/tools/testing/selftests/mm/migration.c
> +++ b/tools/testing/selftests/mm/migration.c
> @@ -5,6 +5,8 @@
>   */
>  
>  #include "../kselftest_harness.h"
> +#include <stdint.h>
> +#include <stdio.h>
>  #include <strings.h>
>  #include <pthread.h>
>  #include <numa.h>
> @@ -14,11 +16,17 @@
>  #include <sys/types.h>
>  #include <signal.h>
>  #include <time.h>
> +#include <unistd.h>
>  
>  #define TWOMEG (2<<20)
>  #define RUNTIME (20)
>  
> +#define GET_BIT(X, Y) ((X & ((uint64_t)1<<Y)) >> Y)
> +#define GET_PFN(X) (X & 0x7FFFFFFFFFFFFFull)
>  #define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
> +#define PAGEMAP_ENTRY 8
> +const int __endian_bit = 1;
> +#define is_bigendian() ((*(char *)&__endian_bit) == 0)
>  
>  FIXTURE(migration)
>  {
> @@ -94,6 +102,47 @@ int migrate(uint64_t *ptr, int n1, int n2)
>  	return 0;
>  }
>  
> +
Trivial, but 3 lines definitely more than needed.

> +
> +int migrate_phys(uint64_t paddr, int n1, int n2)
> +{
> +	int ret, tmp;
> +	int status = 0;
> +	struct timespec ts1, ts2;
> +
> +	if (clock_gettime(CLOCK_MONOTONIC, &ts1))
> +		return -1;
> +
> +	while (1) {
> +		if (clock_gettime(CLOCK_MONOTONIC, &ts2))
> +			return -1;
> +
> +		if (ts2.tv_sec - ts1.tv_sec >= RUNTIME)
> +			return 0;
> +
> +		/*
> +		 * FIXME: move_phys_pages was syscall 454 during RFC.
> +		 * Update this when an official syscall number is adopted
> +		 * and the libnuma interface is implemented.
> +		 */
> +		ret = syscall(454, 1, (void **) &paddr, &n2, &status,
> +			      MPOL_MF_MOVE_ALL);
> +		if (ret) {
> +			if (ret > 0)
> +				printf("Didn't migrate %d pages\n", ret);
> +			else
> +				perror("Couldn't migrate pages");
> +			return -2;
> +		}
> +
> +		tmp = n2;
> +		n2 = n1;
> +		n1 = tmp;
> +	}
> +
> +	return 0;
> +}