Re: [PATCH for vm-scalability] usemem: Add code for touch-alloc

[Wu Fengguang]

Applied, thanks!

On Thu, Apr 08, 2021 at 09:42:55PM +0800, Hui Zhu wrote:
> Add code for touch-alloc.
> And Change read memory to write memory to avoid use the zero-page for
> reads in do_anonymous_page.
>
> Signed-off-by: Hui Zhu <teawater@xxxxxxxxx>
> ---
> usemem.c | 34 ++++++++++++++++++++++------------
> 1 file changed, 22 insertions(+), 12 deletions(-)
>
> diff --git a/usemem.c b/usemem.c
> index e2c46ec..5b90aae 100644
> --- a/usemem.c
> +++ b/usemem.c
> @@ -329,6 +329,18 @@ void detach(void)
> 	}
> }
>
> +unsigned long do_access(unsigned long *p, unsigned long idx, int read)
> +{
> +	volatile unsigned long *vp = p;
> +
> +	if (read)
> +		return vp[idx];	/* read data */
> +	else {
> +		vp[idx] = idx;	/* write data */
> +		return 0;
> +	}
> +}
> +
> unsigned long * allocate(unsigned long bytes)
> {
> 	unsigned long *p;
> @@ -355,6 +367,14 @@ unsigned long * allocate(unsigned long bytes)
> 		p = (unsigned long *)ALIGN((unsigned long)p, pagesize - 1);
> 	}
>
> +	if (opt_touch_alloc) {
> +		unsigned long i;
> +		unsigned long m = bytes / sizeof(*p);
> +
> +		for (i = 0; i < m; i += 1)
> +			do_access(p, i, 0);
> +	}
> +
> 	return p;
> }
>
> @@ -436,18 +456,6 @@ void shm_unlock(int seg_id)
> 	shmctl(seg_id, SHM_UNLOCK, NULL);
> }
>
> -unsigned long do_access(unsigned long *p, unsigned long idx, int read)
> -{
> -	volatile unsigned long *vp = p;
> -
> -	if (read)
> -		return vp[idx];	/* read data */
> -	else {
> -		vp[idx] = idx;	/* write data */
> -		return 0;
> -	}
> -}
> -
> #define NSEC_PER_SEC  (1UL * 1000 * 1000 * 1000)
>
> long nsec_sub(long nsec1, long nsec2)
> @@ -953,6 +961,8 @@ int main(int argc, char *argv[])
> 				opt_punch_holes = 1;
> 			} else if (strcmp(opts[opt_index].name, "init-time") == 0) {
> 				opt_init_time = 1;
> +			} else if (strcmp(opts[opt_index].name, "touch-alloc") == 0) {
> +				opt_touch_alloc = 1;
> 			} else
> 				usage(1);
> 			break;
> --
> 2.17.1