linux-ext4.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Theodore Ts'o <tytso@mit.edu>
To: Zheng Liu <gnehzuil.liu@gmail.com>
Cc: linux-ext4@vger.kernel.org, Zheng Liu <wenqing.lz@taobao.com>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Jan Kara <jack@suse.cz>
Subject: Re: [RFC PATCH v2 0/4] ext4: extents status tree shrinker improvement
Date: Wed, 16 Apr 2014 11:19:38 -0400	[thread overview]
Message-ID: <20140416151938.GA17208@thunk.org> (raw)
In-Reply-To: <1397647830-24444-1-git-send-email-wenqing.lz@taobao.com>

Hi Zheng,

Thanks so much for your deep and detailed work on this.

I have two immediate reactions.

1) We should first fix __ext4_es_shrink so that we interpret
nr_to_scan correctly --- it's the number of objects to scan, not the
number of objects that we need to shirnk.  That should significantly
reduce the number of scans that we do, and fixing this could
potentially influence the metrics that we measure.

2) In addition to measuring the scan time, we should also measure how
many times we end up loading extents from disk when (during the course
of a normal workload) we are under memory pressure, and RR ends up
throwing out an extent that would have been saved in LRU, and so an
additional metadata read would be required when using RR.

	   	    	       	  	   - Ted

  parent reply	other threads:[~2014-04-16 15:19 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-16 11:30 [RFC PATCH v2 0/4] ext4: extents status tree shrinker improvement Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 1/4] ext4: improve extents status tree trace point Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 2/4] ext4: track extent status tree shrinker delay statictics Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 3/4] ext4: improve extents status tree shrinker lru algorithm Zheng Liu
2014-04-16 11:30 ` [RFC PATCH v2 4/4] ext4: use a round-robin algorithm to shrink extent cache Zheng Liu
2014-04-16 15:19 ` Theodore Ts'o [this message]
2014-04-16 15:42   ` [RFC PATCH v2 0/4] ext4: extents status tree shrinker improvement Theodore Ts'o
2014-04-17 15:35     ` Theodore Ts'o
2014-04-21 13:50       ` Zheng Liu
2014-04-21 14:05         ` Theodore Ts'o
2014-04-21 14:46           ` Zheng Liu
2014-04-21 14:54             ` Theodore Ts'o
2014-04-21 23:10       ` Dave Chinner
2014-04-23  5:35         ` Zheng Liu
2014-04-24  1:46           ` Dave Chinner

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=20140416151938.GA17208@thunk.org \
    --to=tytso@mit.edu \
    --cc=adilger.kernel@dilger.ca \
    --cc=gnehzuil.liu@gmail.com \
    --cc=jack@suse.cz \
    --cc=linux-ext4@vger.kernel.org \
    --cc=wenqing.lz@taobao.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;
as well as URLs for NNTP newsgroup(s).