Re: [PATCH 12/14] staging/lustre/llite: update ras window correctly
From: James Simmons
Date: Sun Nov 06 2016 - 20:58:05 EST
> From: Bobi Jam <bobijam.xu@xxxxxxxxx>
>
> When stride-RA hit case miss, we only reset normal sequential
> read-ahead window, but not reset the stride IO to avoid the overhead
> of re-detecting stride IO. While when the normal RA window is set
> to not insect with the stride-RA window, when we try to increase
> the stride-RA window length later, the presumption does not hold.
>
> This patch resets the stride IO as well in this case.
Reviewed-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
> Signed-off-by: Bobi Jam <bobijam.xu@xxxxxxxxx>
> Reviewed-on: http://review.whamcloud.com/23032
> Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8683
> Reviewed-by: wangdi <di.wang@xxxxxxxxx>
> Reviewed-by: Jinshan Xiong <jinshan.xiong@xxxxxxxxx>
> Signed-off-by: Oleg Drokin <green@xxxxxxxxxxxxxx>
> ---
> drivers/staging/lustre/lustre/llite/rw.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/lustre/lustre/llite/rw.c b/drivers/staging/lustre/lustre/llite/rw.c
> index d2515a8..e34017d 100644
> --- a/drivers/staging/lustre/lustre/llite/rw.c
> +++ b/drivers/staging/lustre/lustre/llite/rw.c
> @@ -809,13 +809,20 @@ static void ras_update(struct ll_sb_info *sbi, struct inode *inode,
> if (ra_miss) {
> if (index_in_stride_window(ras, index) &&
> stride_io_mode(ras)) {
> - /*If stride-RA hit cache miss, the stride dector
> - *will not be reset to avoid the overhead of
> - *redetecting read-ahead mode
> - */
> if (index != ras->ras_last_readpage + 1)
> ras->ras_consecutive_pages = 0;
> ras_reset(inode, ras, index);
> +
> + /* If stride-RA hit cache miss, the stride
> + * detector will not be reset to avoid the
> + * overhead of redetecting read-ahead mode,
> + * but on the condition that the stride window
> + * is still intersect with normal sequential
> + * read-ahead window.
> + */
> + if (ras->ras_window_start <
> + ras->ras_stride_offset)
> + ras_stride_reset(ras);
> RAS_CDEBUG(ras);
> } else {
> /* Reset both stride window and normal RA
> --
> 2.7.4
>
>