From: Josef Bacik <josef@toxicpanda.com>
To: Dennis Zhou <dennis@kernel.org>
Cc: David Sterba <dsterba@suse.com>, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
Omar Sandoval <osandov@osandov.com>,
kernel-team@fb.com, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 04/22] btrfs: keep track of cleanliness of the bitmap
Date: Fri, 8 Nov 2019 14:12:45 -0500 [thread overview]
Message-ID: <20191108191244.kcbgfsmzbfpzivri@macbook-pro-91.dhcp.thefacebook.com> (raw)
In-Reply-To: <6563f9fc4cd47bade586d86c658c848f2ffeaa49.1571865774.git.dennis@kernel.org>
On Wed, Oct 23, 2019 at 06:52:58PM -0400, Dennis Zhou wrote:
> There is a cap in btrfs in the amount of free extents that a block group
> can have. When it surpasses that threshold, future extents are placed
> into bitmaps. Instead of keeping track of if a certain bit is trimmed or
> not in a second bitmap, keep track of the relative state of the bitmap.
>
> With async discard, trimming bitmaps becomes a more frequent operation.
> As a trade off with simplicity, we keep track of if discarding a bitmap
> is in progress. If we fully scan a bitmap and trim as necessary, the
> bitmap is marked clean. This has some caveats as the min block size may
> skip over regions deemed too small. But this should be a reasonable
> trade off rather than keeping a second bitmap and making allocation
> paths more complex. The downside is we may overtrim, but ideally the min
> block size should prevent us from doing that too often and getting stuck
> trimming pathological cases.
>
> BTRFS_TRIM_STATE_TRIMMING is added to indicate a bitmap is in the
> process of being trimmed. If additional free space is added to that
> bitmap, the bit is cleared. A bitmap will be marked
> BTRFS_TRIM_STATE_TRIMMED if the trimming code was able to reach the end
> of it and the former is still set.
>
> Signed-off-by: Dennis Zhou <dennis@kernel.org>
> ---
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Thanks,
Josef
next prev parent reply other threads:[~2019-11-08 19:12 UTC|newest]
Thread overview: 47+ 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 [this message]
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
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 04/22] btrfs: keep track of cleanliness of the bitmap Dennis Zhou
2019-11-23 0:17 ` kbuild test robot
2019-11-25 13:59 ` David Sterba
2019-11-25 19:37 ` Dennis Zhou
2019-11-25 19:46 [PATCH v4 00/22] btrfs: async discard support Dennis Zhou
2019-11-25 19:46 ` [PATCH 04/22] btrfs: keep track of cleanliness of the bitmap Dennis Zhou
2019-12-09 19:45 [PATCH v5 00/22] btrfs: async discard support Dennis Zhou
2019-12-09 19:45 ` [PATCH 04/22] btrfs: keep track of cleanliness of the bitmap Dennis Zhou
2019-12-14 0:22 [PATCH v6 00/22] btrfs: async discard support Dennis Zhou
2019-12-14 0:22 ` [PATCH 04/22] btrfs: keep track of cleanliness of the bitmap Dennis Zhou
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