public inbox for linux-xfs@vger.kernel.org
 help / color / mirror / Atom feed
From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 07/10] repair: prefetch runs too far ahead
Date: Wed, 26 Feb 2014 16:51:09 +1100	[thread overview]
Message-ID: <20140226055109.GQ13647@dastard> (raw)
In-Reply-To: <20140226015250.GB3616@infradead.org>

On Tue, Feb 25, 2014 at 05:52:50PM -0800, Christoph Hellwig wrote:
> 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.

I was fiddling with the magic number to see if it affected the
readahead behaviour (it didn't) and forgot to set it back to the
original value. Will fix.

> 
> > +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.

Actually, that's pretty much what this patch does in this hunk:

@@ -905,12 +945,8 @@ do_inode_prefetch(
         */
        if (!stride) {
                queue.mp = mp;
-               pf_args[0] = start_inode_prefetch(0, dirs_only, NULL);
-               for (i = 0; i < mp->m_sb.sb_agcount; i++) {
-                       pf_args[(~i) & 1] = start_inode_prefetch(i + 1,
-                                       dirs_only, pf_args[i & 1]);
-                       func(&queue, i, pf_args[i & 1]);
-               }
+               prefetch_ag_range(&queue, 0, mp->m_sb.sb_agcount,
+                                 dirs_only, func);
                return;
        }


Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

  reply	other threads:[~2014-02-26  5:51 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-24  6:29 [PATCH 00/10, v2] repair: scalability and prefetch fixes Dave Chinner
2014-02-24  6:29 ` [PATCH 01/10] repair: translation lookups limit scalability Dave Chinner
2014-02-24 20:42   ` Brian Foster
2014-02-25 20:01   ` Christoph Hellwig
2014-02-24  6:29 ` [PATCH 02/10] repair: per AG locks contend for cachelines Dave Chinner
2014-02-24  6:29 ` [PATCH 03/10] libxfs: buffer cache hashing is suboptimal Dave Chinner
2014-02-24  6:29 ` [PATCH 04/10] repair: limit auto-striding concurrency apprpriately Dave Chinner
2014-02-24  6:29 ` [PATCH 05/10] repair: factor out threading setup code Dave Chinner
2014-02-24 20:43   ` Brian Foster
2014-02-24 23:16     ` Dave Chinner
2014-02-24 23:30       ` Brian Foster
2014-02-24  6:29 ` [PATCH 06/10] repair: use a listhead for the dotdot list Dave Chinner
2014-02-25 20:03   ` Christoph Hellwig
2014-02-27  2:06     ` Dave Chinner
2014-02-24  6:29 ` [PATCH 07/10] repair: prefetch runs too far ahead Dave Chinner
2014-02-26  1:52   ` Christoph Hellwig
2014-02-26  5:51     ` Dave Chinner [this message]
2014-02-24  6:29 ` [PATCH 08/10] libxfs: remove a couple of locks Dave Chinner
2014-02-25 20:05   ` Christoph Hellwig
2014-02-25 23:43     ` Dave Chinner
2014-02-26  1:54       ` Christoph Hellwig
2014-02-26  5:53         ` Dave Chinner
2014-02-24  6:29 ` [PATCH 09/10] repair: fix prefetch queue limiting Dave Chinner
2014-02-25 20:08   ` Christoph Hellwig
2014-02-24  6:29 ` [PATCH 10/10] repair: BMBT prefetch needs to be CRC aware Dave Chinner
2014-02-25 17:25   ` Christoph Hellwig
2014-02-25 23:51     ` Dave Chinner
2014-02-26  1:40       ` Christoph Hellwig
2014-02-26  1:44   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20140226055109.GQ13647@dastard \
    --to=david@fromorbit.com \
    --cc=hch@infradead.org \
    --cc=xfs@oss.sgi.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox