[Skiboot] [PATCH v2] libflash/file: greatly increase perf of file_erase()

[Samuel Mendoza-Jonas]

On Mon, 2018-12-03 at 11:05 +1100, Stewart Smith wrote:
> Do 4096 byte chunks not 8 byte chunks. A ffspart invocation constructing
> a 64MB PNOR goes from a couple of seconds to ~0.1seconds with this
> patch.
> 
> Signed-off-by: Stewart Smith <stewart at linux.ibm.com>

Reviewed-by: Samuel Mendoza-Jonas <sam at mendozajonas.com>

> ---
> v2: use git properly you git (i.e. don't remove a file)
> 
>  libflash/file.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/libflash/file.c b/libflash/file.c
> index 49f61778e946..72765b5777f9 100644
> --- a/libflash/file.c
> +++ b/libflash/file.c
> @@ -117,15 +117,17 @@ static int file_write(struct blocklevel_device *bl, uint64_t dst, const void *sr
>   */
>  static int file_erase(struct blocklevel_device *bl, uint64_t dst, uint64_t len)
>  {
> -	unsigned long long int d = ULLONG_MAX;
> +	char buf[4096];
>  	int i = 0;
>  	int rc;
>  
> +	memset(buf, ~0, sizeof(buf));
> +
>  	while (len - i > 0) {
> -		rc = file_write(bl, dst + i, &d, len - i > sizeof(d) ? sizeof(d) : len - i);
> +		rc = file_write(bl, dst + i, buf, len - i > sizeof(buf) ? sizeof(buf) : len - i);
>  		if (rc)
>  			return rc;
> -		i += len - i > sizeof(d) ? sizeof(d) : len - i;
> +		i += (len - i > sizeof(buf)) ? sizeof(buf) : len - i;
>  	}
>  
>  	return 0;