Re: [PATCH v3] xfs: introduce object readahead to log recovery

[Zhi Yong Wu]

HI, xfs maintainers,

any comments?

On Wed, Jul 31, 2013 at 4:42 PM,  <zwu.kernel@xxxxxxxxx> wrote:
> From: Zhi Yong Wu <wuzhy@xxxxxxxxxxxxxxxxxx>
>
>   It can take a long time to run log recovery operation because it is
> single threaded and is bound by read latency. We can find that it took
> most of the time to wait for the read IO to occur, so if one object
> readahead is introduced to log recovery, it will obviously reduce the
> log recovery time.
>
> Log recovery time stat:
>
>           w/o this patch        w/ this patch
>
> real:        0m15.023s             0m7.802s
> user:        0m0.001s              0m0.001s
> sys:         0m0.246s              0m0.107s
>
> Signed-off-by: Zhi Yong Wu <wuzhy@xxxxxxxxxxxxxxxxxx>
> ---
>  fs/xfs/xfs_log_recover.c | 159 +++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 153 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index 7681b19..ebb00bc 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -3116,6 +3116,106 @@ xlog_recover_free_trans(
>         kmem_free(trans);
>  }
>
> +STATIC void
> +xlog_recover_buffer_ra_pass2(
> +       struct xlog                     *log,
> +       struct xlog_recover_item        *item)
> +{
> +       struct xfs_buf_log_format       *buf_f = item->ri_buf[0].i_addr;
> +       struct xfs_mount                *mp = log->l_mp;
> +
> +       if (xlog_check_buffer_cancelled(log, buf_f->blf_blkno,
> +                       buf_f->blf_len, buf_f->blf_flags)) {
> +               return;
> +       }
> +
> +       xfs_buf_readahead(mp->m_ddev_targp, buf_f->blf_blkno,
> +                               buf_f->blf_len, NULL);
> +}
> +
> +STATIC void
> +xlog_recover_inode_ra_pass2(
> +       struct xlog                     *log,
> +       struct xlog_recover_item        *item)
> +{
> +       struct xfs_inode_log_format     ilf_buf;
> +       struct xfs_inode_log_format     *ilfp;
> +       struct xfs_mount                *mp = log->l_mp;
> +       int                     error;
> +
> +       if (item->ri_buf[0].i_len == sizeof(struct xfs_inode_log_format)) {
> +               ilfp = item->ri_buf[0].i_addr;
> +       } else {
> +               ilfp = &ilf_buf;
> +               memset(ilfp, 0, sizeof(*ilfp));
> +               error = xfs_inode_item_format_convert(&item->ri_buf[0], ilfp);
> +               if (error)
> +                       return;
> +       }
> +
> +       if (xlog_check_buffer_cancelled(log, ilfp->ilf_blkno, ilfp->ilf_len, 0))
> +               return;
> +
> +       xfs_buf_readahead(mp->m_ddev_targp, ilfp->ilf_blkno,
> +                               ilfp->ilf_len, &xfs_inode_buf_ops);
> +}
> +
> +STATIC void
> +xlog_recover_dquot_ra_pass2(
> +       struct xlog                     *log,
> +       struct xlog_recover_item        *item)
> +{
> +       struct xfs_mount        *mp = log->l_mp;
> +       struct xfs_disk_dquot   *recddq;
> +       struct xfs_dq_logformat *dq_f;
> +       uint                    type;
> +
> +
> +       if (mp->m_qflags == 0)
> +               return;
> +
> +       recddq = item->ri_buf[1].i_addr;
> +       if (recddq == NULL)
> +               return;
> +       if (item->ri_buf[1].i_len < sizeof(struct xfs_disk_dquot))
> +               return;
> +
> +       type = recddq->d_flags & (XFS_DQ_USER | XFS_DQ_PROJ | XFS_DQ_GROUP);
> +       ASSERT(type);
> +       if (log->l_quotaoffs_flag & type)
> +               return;
> +
> +       dq_f = item->ri_buf[0].i_addr;
> +       ASSERT(dq_f);
> +       ASSERT(dq_f->qlf_len == 1);
> +
> +       xfs_buf_readahead(mp->m_ddev_targp, dq_f->qlf_blkno,
> +                               dq_f->qlf_len, NULL);
> +}
> +
> +STATIC void
> +xlog_recover_ra_pass2(
> +       struct xlog                     *log,
> +       struct xlog_recover_item        *item)
> +{
> +       switch (ITEM_TYPE(item)) {
> +       case XFS_LI_BUF:
> +               xlog_recover_buffer_ra_pass2(log, item);
> +               break;
> +       case XFS_LI_INODE:
> +               xlog_recover_inode_ra_pass2(log, item);
> +               break;
> +       case XFS_LI_DQUOT:
> +               xlog_recover_dquot_ra_pass2(log, item);
> +               break;
> +       case XFS_LI_EFI:
> +       case XFS_LI_EFD:
> +       case XFS_LI_QUOTAOFF:
> +       default:
> +               break;
> +       }
> +}
> +
>  STATIC int
>  xlog_recover_commit_pass1(
>         struct xlog                     *log,
> @@ -3177,6 +3277,26 @@ xlog_recover_commit_pass2(
>         }
>  }
>
> +STATIC int
> +xlog_recover_items_pass2(
> +       struct xlog                     *log,
> +       struct xlog_recover             *trans,
> +       struct list_head                *buffer_list,
> +       struct list_head                *item_list)
> +{
> +       struct xlog_recover_item        *item;
> +       int                             error = 0;
> +
> +       list_for_each_entry(item, item_list, ri_list) {
> +               error = xlog_recover_commit_pass2(log, trans,
> +                                         buffer_list, item);
> +               if (error)
> +                       return error;
> +       }
> +
> +       return error;
> +}
> +
>  /*
>   * Perform the transaction.
>   *
> @@ -3189,9 +3309,16 @@ xlog_recover_commit_trans(
>         struct xlog_recover     *trans,
>         int                     pass)
>  {
> -       int                     error = 0, error2;
> -       xlog_recover_item_t     *item;
> -       LIST_HEAD               (buffer_list);
> +       int                             error = 0;
> +       int                             error2;
> +       int                             items_queued = 0;
> +       struct xlog_recover_item        *item;
> +       struct xlog_recover_item        *next;
> +       LIST_HEAD                       (buffer_list);
> +       LIST_HEAD                       (ra_list);
> +       LIST_HEAD                       (done_list);
> +
> +       #define XLOG_RECOVER_COMMIT_QUEUE_MAX 100
>
>         hlist_del(&trans->r_list);
>
> @@ -3199,14 +3326,22 @@ xlog_recover_commit_trans(
>         if (error)
>                 return error;
>
> -       list_for_each_entry(item, &trans->r_itemq, ri_list) {
> +       list_for_each_entry_safe(item, next, &trans->r_itemq, ri_list) {
>                 switch (pass) {
>                 case XLOG_RECOVER_PASS1:
>                         error = xlog_recover_commit_pass1(log, trans, item);
>                         break;
>                 case XLOG_RECOVER_PASS2:
> -                       error = xlog_recover_commit_pass2(log, trans,
> -                                                         &buffer_list, item);
> +                       xlog_recover_ra_pass2(log, item);
> +                       list_move_tail(&item->ri_list, &ra_list);
> +                       items_queued++;
> +                       if (items_queued >= XLOG_RECOVER_COMMIT_QUEUE_MAX) {
> +                               error = xlog_recover_items_pass2(log, trans,
> +                                               &buffer_list, &ra_list);
> +                               list_splice_tail_init(&ra_list, &done_list);
> +                               items_queued = 0;
> +                       }
> +
>                         break;
>                 default:
>                         ASSERT(0);
> @@ -3216,6 +3351,18 @@ xlog_recover_commit_trans(
>                         goto out;
>         }
>
> +       if (!list_empty(&ra_list)) {
> +               error = xlog_recover_items_pass2(log, trans,
> +                               &buffer_list, &ra_list);
> +               if (error)
> +                       goto out;
> +
> +               list_splice_tail_init(&ra_list, &done_list);
> +       }
> +
> +       if (!list_empty(&done_list))
> +               list_splice_init(&done_list, &trans->r_itemq);
> +
>         xlog_recover_free_trans(trans);
>
>  out:
> --
> 1.7.11.7
>
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs



-- 
Regards,

Zhi Yong Wu
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