Re: [PATCH] improve the performance of large sequential write NFS workloads

Jan Kara
2010-01-06T20:09:40Z

On Wed 06-01-10 14:53:14, Trond Myklebust wrote:
> ...and finally, this should convert the previous NFS patch to use the
> per-bdi accounting.
>
> Cheers
> Trond
>
> --------------------------------------------------------------------------------------
> VM: Use per-bdi unstable accounting to improve use of wbc->force_commit
>
> From: Trond Myklebust <Trond.Myklebust@netapp.com>
>
> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
I like this. You can add
Acked-by: Jan Kara <jack@suse.cz>
to this patch previous patches adding unstable pages accounting.

Honza
> ---
>
> mm/page-writeback.c | 13 +++++++------
> 1 files changed, 7 insertions(+), 6 deletions(-)
>
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index d90a0db..c537543 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -487,7 +487,6 @@ static void balance_dirty_pages(struct address_space *mapping,
> {
> long nr_reclaimable, bdi_nr_reclaimable;
> long nr_writeback, bdi_nr_writeback;
> - long nr_unstable_nfs;
> unsigned long background_thresh;
> unsigned long dirty_thresh;
> unsigned long bdi_thresh;
> @@ -504,18 +503,20 @@ static void balance_dirty_pages(struct address_space *mapping,
> .nr_to_write = write_chunk,
> .range_cyclic = 1,
> };
> + long bdi_nr_unstable = 0;
>
> get_dirty_limits(&background_thresh, &dirty_thresh,
> &bdi_thresh, bdi);
>
> - nr_unstable_nfs = global_page_state(NR_UNSTABLE_NFS);
> nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
> - nr_unstable_nfs;
> + global_page_state(NR_UNSTABLE_NFS);
> nr_writeback = global_page_state(NR_WRITEBACK);
>
> bdi_nr_reclaimable = bdi_stat(bdi, BDI_DIRTY);
> - if (bdi_cap_account_unstable(bdi))
> - bdi_nr_reclaimable += bdi_stat(bdi, BDI_UNSTABLE);
> + if (bdi_cap_account_unstable(bdi)) {
> + bdi_nr_unstable = bdi_stat(bdi, BDI_UNSTABLE);
> + bdi_nr_reclaimable += bdi_nr_unstable;
> + }
> bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
>
> if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh)
> @@ -545,7 +546,7 @@ static void balance_dirty_pages(struct address_space *mapping,
> if (bdi_nr_reclaimable > bdi_thresh) {
> wbc.force_commit = 0;
> /* Force NFS to also free up unstable writes. */
> - if (nr_unstable_nfs > nr_reclaimable / 2)
> + if (bdi_nr_unstable > bdi_nr_reclaimable / 2)
> wbc.force_commit = 1;
>
> writeback_inodes_wbc(&wbc);
>
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR