On Sat, Feb 23, 2013 at 05:58:00PM -0500, Phillip Susi wrote:
> The previous implementation initiated writeout for a non congested bdi, and
> then discarded any clean pages. This had 3 problems:
>
> 1) The writeout would spin up the disk unnecessarily
> 2) Discarding pages under low cache pressure is a waste
> 3) It was useless on files being written, and thus full of dirty pages
>
> Now we just move the pages to the inactive list so they will be reclaimed
> sooner.
Hi Phillip,
I think we need to initiate writeout. IIRC, when we try to free pages,
we would wait on page writeback. That will cause a huge latency for
some applications. If these pages have been written out, we just need
to invalidate them. IMO we can move these pages to inactive list and
write them out.
Regards,
- Zheng
> ---
> include/linux/fs.h | 2 ++
> mm/fadvise.c | 8 ++------
> mm/filemap.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 47 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 7d2e893..2abd193 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2198,6 +2198,8 @@ extern int __filemap_fdatawrite_range(struct address_space *mapping,
> loff_t start, loff_t end, int sync_mode);
> extern int filemap_fdatawrite_range(struct address_space *mapping,
> loff_t start, loff_t end);
> +extern void filemap_deactivate_range(struct address_space *mapping, pgoff_t start,
> + pgoff_t end);
>
> extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
> int datasync);
> diff --git a/mm/fadvise.c b/mm/fadvise.c
> index a47f0f5..fbd58b0 100644
> --- a/mm/fadvise.c
> +++ b/mm/fadvise.c
> @@ -112,17 +112,13 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
> case POSIX_FADV_NOREUSE:
> break;
> case POSIX_FADV_DONTNEED:
> - if (!bdi_write_congested(mapping->backing_dev_info))
> - __filemap_fdatawrite_range(mapping, offset, endbyte,
> - WB_SYNC_NONE);
> -
> /* First and last FULL page! */
> start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
> end_index = (endbyte >> PAGE_CACHE_SHIFT);
>
> if (end_index >= start_index)
> - invalidate_mapping_pages(mapping, start_index,
> - end_index);
> + filemap_deactivate_range(mapping, start_index,
> + end_index);
> break;
> default:
> ret = -EINVAL;
> diff --git a/mm/filemap.c b/mm/filemap.c
> index c610076..bcdcdbf 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -217,7 +217,49 @@ int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
> return ret;
> }
>
> +/**
> + * filemap_deactivate_range - moves pages in range to the inactive list
> + * @mapping: the address_space which holds the pages to deactivate
> + * @start: offset where the range starts
> + * @end: offset where the range ends (inclusive)
> + */
> +void filemap_deactivate_range(struct address_space *mapping, pgoff_t start,
> + pgoff_t end)
> +{
> + struct pagevec pvec;
> + pgoff_t index = start;
> + int i;
> +
> + /*
> + * Note: this function may get called on a shmem/tmpfs mapping:
> + * pagevec_lookup() might then return 0 prematurely (because it
> + * got a gangful of swap entries); but it's hardly worth worrying
> + * about - it can rarely have anything to free from such a mapping
> + * (most pages are dirty), and already skips over any difficulties.
> + */
> +
> + pagevec_init(&pvec, 0);
> + while (index <= end && pagevec_lookup(&pvec, mapping, index,
> + min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
> + mem_cgroup_uncharge_start();
> + for (i = 0; i < pagevec_count(&pvec); i++) {
> + struct page *page = pvec.pages[i];
> +
> + /* We rely upon deletion not changing page->index */
> + index = page->index;
> + if (index > end)
> + break;
> +
> + WARN_ON(page->index != index);
> + deactivate_page(page);
> + }
> + pagevec_release(&pvec);
> + mem_cgroup_uncharge_end();
> + cond_resched();
> + index++;
> + }
> +}
> +
> static inline int __filemap_fdatawrite(struct address_space *mapping,
> int sync_mode)
> {
> --
> 1.8.1.2
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@xxxxxxxxx. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>