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From: David Sterba <dsterba@suse.cz>
To: Dennis Zhou <dennis@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>,
	David Sterba <dsterba@suse.com>, Chris Mason <clm@fb.com>,
	Omar Sandoval <osandov@osandov.com>,
	kernel-team@fb.com, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 18/22] btrfs: only keep track of data extents for async discard
Date: Fri, 15 Nov 2019 18:31:37 +0100
Message-ID: <20191115173137.GC3001@twin.jikos.cz> (raw)
In-Reply-To: <20191108201458.GA51086@dennisz-mbp>

On Fri, Nov 08, 2019 at 03:14:58PM -0500, Dennis Zhou wrote:
> On Fri, Nov 08, 2019 at 02:46:51PM -0500, Josef Bacik wrote:
> > On Wed, Oct 23, 2019 at 06:53:12PM -0400, Dennis Zhou wrote:
> > > As mentioned earlier, discarding data can be done either by issuing an
> > > explicit discard or implicitly by reusing the LBA. Metadata chunks see
> > > much more frequent reuse due to well it being metadata. So instead of
> > > explicitly discarding metadata blocks, just leave them be and let the
> > > latter implicit discarding be done for them.
> > > 
> > 
> > Hmm now that I look at this, it seems like we won't even discard empty metadata
> > block groups now, right?  Or am I missing something?  Thanks,
> > 
> 
> Empty block groups go through btrfs_add_to_discard_unused_list() which
> skips that check. So metadata blocks will be discarded here from
> btrfs_discard_queue_work() which should be called from
> __btrfs_add_free_space().
> 
> We should just skip discarding metadata blocks while they are being
> used.

I believe discarding metadata blocks while in use is called corruption :)
But I understand what you mean.

  reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-23 22:52 [PATCH v2 00/22] btrfs: async discard support Dennis Zhou
2019-10-23 22:52 ` [PATCH 01/22] bitmap: genericize percpu bitmap region iterators Dennis Zhou
2019-10-23 22:52 ` [PATCH 02/22] btrfs: rename DISCARD opt to DISCARD_SYNC Dennis Zhou
2019-10-23 22:52 ` [PATCH 03/22] btrfs: keep track of which extents have been discarded Dennis Zhou
2019-11-08 19:05   ` Josef Bacik
2019-11-11 17:20     ` Dennis Zhou
2019-10-23 22:52 ` [PATCH 04/22] btrfs: keep track of cleanliness of the bitmap Dennis Zhou
2019-11-08 19:12   ` Josef Bacik
2019-10-23 22:52 ` [PATCH 05/22] btrfs: add the beginning of async discard, discard workqueue Dennis Zhou
2019-11-11 18:49   ` David Sterba
2019-10-23 22:53 ` [PATCH 06/22] btrfs: handle empty block_group removal Dennis Zhou
2019-11-08 19:19   ` Josef Bacik
2019-10-23 22:53 ` [PATCH 07/22] btrfs: discard one region at a time in async discard Dennis Zhou
2019-11-08 19:27   ` Josef Bacik
2019-10-23 22:53 ` [PATCH 08/22] btrfs: add removal calls for sysfs debug/ Dennis Zhou
2019-11-08 19:28   ` Josef Bacik
2019-10-23 22:53 ` [PATCH 09/22] btrfs: make UUID/debug have its own kobject Dennis Zhou
2019-11-08 19:29   ` Josef Bacik
2019-10-23 22:53 ` [PATCH 10/22] btrfs: add discard sysfs directory Dennis Zhou
2019-11-08 19:29   ` Josef Bacik
2019-10-23 22:53 ` [PATCH 11/22] btrfs: track discardable extents for async discard Dennis Zhou
2019-10-23 22:53 ` [PATCH 12/22] btrfs: keep track of discardable_bytes Dennis Zhou
2019-11-08 19:31   ` Josef Bacik
2019-10-23 22:53 ` [PATCH 13/22] btrfs: calculate discard delay based on number of extents Dennis Zhou
2019-10-23 22:53 ` [PATCH 14/22] btrfs: add bps discard rate limit Dennis Zhou
2019-11-08 19:41   ` Josef Bacik
2019-11-15 17:28     ` David Sterba
2019-10-23 22:53 ` [PATCH 15/22] btrfs: limit max discard size for async discard Dennis Zhou
2019-10-23 22:53 ` [PATCH 16/22] btrfs: make max async discard size tunable Dennis Zhou
2019-10-23 22:53 ` [PATCH 17/22] btrfs: have multiple discard lists Dennis Zhou
2019-11-08 19:44   ` Josef Bacik
2019-10-23 22:53 ` [PATCH 18/22] btrfs: only keep track of data extents for async discard Dennis Zhou
2019-11-08 19:46   ` Josef Bacik
2019-11-08 20:14     ` Dennis Zhou
2019-11-15 17:31       ` David Sterba [this message]
2019-10-23 22:53 ` [PATCH 19/22] btrfs: keep track of discard reuse stats Dennis Zhou
2019-10-23 22:53 ` [PATCH 20/22] btrfs: add async discard header Dennis Zhou
2019-10-23 22:53 ` [PATCH 21/22] btrfs: increase the metadata allowance for the free_space_cache Dennis Zhou
2019-10-23 22:53 ` [PATCH 22/22] btrfs: make smaller extents more likely to go into bitmaps Dennis Zhou
2019-11-15 17:40 ` [PATCH v2 00/22] btrfs: async discard support David Sterba
2019-11-20 21:50 [PATCH v3 " Dennis Zhou
2019-11-20 21:51 ` [PATCH 18/22] btrfs: only keep track of data extents for async discard Dennis Zhou
2019-11-25 19:46 [PATCH v4 00/22] btrfs: async discard support Dennis Zhou
2019-11-25 19:46 ` [PATCH 18/22] btrfs: only keep track of data extents for async discard Dennis Zhou
2019-12-09 19:45 [PATCH v5 00/22] btrfs: async discard support Dennis Zhou
2019-12-09 19:46 ` [PATCH 18/22] btrfs: only keep track of data extents for async discard Dennis Zhou

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