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Re: [PATCH 07/10] repair: prefetch runs too far ahead

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 07/10] repair: prefetch runs too far ahead
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Tue, 25 Feb 2014 17:52:50 -0800
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1393223369-4696-8-git-send-email-david@xxxxxxxxxxxxx>
References: <1393223369-4696-1-git-send-email-david@xxxxxxxxxxxxx> <1393223369-4696-8-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Mon, Feb 24, 2014 at 05:29:26PM +1100, Dave Chinner wrote:
> @@ -842,7 +842,7 @@ start_inode_prefetch(
>        * and not any other associated metadata like directories
>        */
>  
> -     max_queue = libxfs_bcache->c_maxcount / thread_count / 8;
> +     max_queue = libxfs_bcache->c_maxcount / thread_count / 32;

I can't correlate this to anything mentioned in the changelog.
Also if you're touching it anyway it might be a good idea to document
the magic number here.

> +void
> +prefetch_ag_range(
> +     struct work_queue       *work,
> +     xfs_agnumber_t          start_ag,
> +     xfs_agnumber_t          end_ag,
> +     bool                    dirs_only,
> +     void                    (*func)(struct work_queue *,
> +                                     xfs_agnumber_t, void *))
> +{
> +     int                     i;
> +     struct prefetch_args    *pf_args[2];
> +
> +     pf_args[start_ag & 1] = start_inode_prefetch(start_ag, dirs_only, NULL);
> +     for (i = start_ag; i < end_ag; i++) {
> +             /* Don't prefetch end_ag */
> +             if (i + 1 < end_ag)
> +                     pf_args[(~i) & 1] = start_inode_prefetch(i + 1,
> +                                             dirs_only, pf_args[i & 1]);
> +             func(work, i, pf_args[i & 1]);
> +     }
> +}

This seems to largely duplicate the common code added in patch 5.
Having _range variants of those that the non-range ones wrap with 0 and
mp->m_sb.sb_agcount as default parameters would avoid that duplication.

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