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SubjectRe: [PATCH 4/5] ide-tape: improve buffer pages freeing strategy
Date
On Saturday 29 March 2008, Borislav Petkov wrote:
> Instead of freeing pages one by one, free them 2^order-wise. Also, mv
> __idetape_kfree_stage() to ide_tape_kfree_buffer().
>
> Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
> ---
> drivers/ide/ide-tape.c | 37 +++++++++++++++++++------------------
> 1 files changed, 19 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
> index cf4351c..dcaefef 100644
> --- a/drivers/ide/ide-tape.c
> +++ b/drivers/ide/ide-tape.c
> @@ -583,20 +583,21 @@ static void idetape_analyze_error(ide_drive_t *drive, u8 *sense)
> }
> }
>
> -/* Free a stage along with its related buffers completely. */
> -static void __idetape_kfree_stage(idetape_stage_t *stage)
> +/* Free data buffers completely. */
> +static void ide_tape_kfree_buffer(idetape_stage_t *stage)
> {
> struct idetape_bh *prev_bh, *bh = stage->bh;
> - int size;
> -
> - while (bh != NULL) {
> - if (bh->b_data != NULL) {
> - size = (int) bh->b_size;
> - while (size > 0) {
> - free_page((unsigned long) bh->b_data);
> - size -= PAGE_SIZE;
> - bh->b_data += PAGE_SIZE;
> - }
> +
> + while (bh) {
> + u32 size = bh->b_size;
> +
> + while (size) {
> + unsigned int order = fls(size >> PAGE_SHIFT)-1;
> +
> + if (bh->b_data)
> + free_pages((unsigned long)bh->b_data, order);
> +
> + size &= (order-1);
> }

Hmmm, don't we also need to update bh->b_data?

[ I added the change below to the merged patch version for now: ]

@@ -598,6 +598,7 @@
free_pages((unsigned long)bh->b_data, order);

size &= (order-1);
+ bh->b_data += (1 << order) * PAGE_SIZE;
}
prev_bh = bh;
bh = bh->b_reqnext;


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