[PATCH] lib: sparse: allocate blkcnt instead of arbitrary small number

[qianfan]

在 2023/6/16 21:26, Mattijs Korpershoek 写道:
> Commit 62649165cb02 ("lib: sparse: Make CHUNK_TYPE_RAW buffer aligned")
> fixed cache alignment for systems with a D-CACHE.
>
> However it introduced some performance regressions [1] on system
> flashing huge images, such as Android.
>
> On AM62x SK EVM, we also observe such performance penalty:
> Sending sparse 'super' 1/2 (768793 KB)             OKAY [ 23.954s]
> Writing 'super'                                    OKAY [ 75.926s]
> Sending sparse 'super' 2/2 (629819 KB)             OKAY [ 19.641s]
> Writing 'super'                                    OKAY [ 62.849s]
> Finished. Total time: 182.474s
>
> The reason for this is that we use an arbitrary small buffer
> (info->blksz * 100) for transferring.
>
> Fix it by using a bigger buffer (info->blksz * blkcnt) as suggested in
> the original's patch review [2].
>
> With this patch, performance impact is mitigated:
> Sending sparse 'super' 1/2 (768793 KB)             OKAY [ 24.006s]
> Writing 'super'                                    OKAY [ 15.920s]
> Sending sparse 'super' 2/2 (629819 KB)             OKAY [ 19.651s]
> Writing 'super'                                    OKAY [ 14.665s]
> Finished. Total time: 74.346s
>
> [1] https://lore.kernel.org/r/20221118121323.4009193-1-gary.bisson@boundarydevices.com
> [2] https://lore.kernel.org/r/all/43e4c17c-4483-ec8e-f843-9b4c5569bd18@seco.com/
>
> Fixes: 62649165cb02 ("lib: sparse: Make CHUNK_TYPE_RAW buffer aligned")
> Signed-off-by: Mattijs Korpershoek <mkorpershoek at baylibre.com>
> ---
>   lib/image-sparse.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/image-sparse.c b/lib/image-sparse.c
> index 5ec0f94ab3eb..25aed0604192 100644
> --- a/lib/image-sparse.c
> +++ b/lib/image-sparse.c
> @@ -55,7 +55,7 @@ static lbaint_t write_sparse_chunk_raw(struct sparse_storage *info,
>   				       void *data,
>   				       char *response)
>   {
> -	lbaint_t n = blkcnt, write_blks, blks = 0, aligned_buf_blks = 100;
> +	lbaint_t n = blkcnt, write_blks, blks = 0, aligned_buf_blks = blkcnt;
Hi:

It's a good point that this code report the performance was affected by 
write large small
mmc blks, not memory copy.

And I can not make sure whether memalign can always alloc such huge 
memory when we change the
aligned_buf_blks to blkcnt.

Could you please set aligned_buf_blks to FASTBOOT_MAX_BLK_WRITE(16384) 
and test again?
>   	uint32_t *aligned_buf = NULL;
>   
>   	if (CONFIG_IS_ENABLED(SYS_DCACHE_OFF)) {
>
> ---
> base-commit: 2f4664f5c3edc55b18d8906f256a4c8e303243c0
> change-id: 20230616-sparse-flash-fix-9c2852aa8d16
>
> Best regards,