From: David Sterba <email@example.com> To: Dennis Zhou <firstname.lastname@example.org> Cc: David Sterba <email@example.com>, David Sterba <firstname.lastname@example.org>, Chris Mason <email@example.com>, Josef Bacik <firstname.lastname@example.org>, Omar Sandoval <email@example.com>, firstname.lastname@example.org, email@example.com Subject: Re: [PATCH v6 00/22] btrfs: async discard support Date: Thu, 19 Dec 2019 21:06:07 +0100 Message-ID: <20191219200607.GQ3929@twin.jikos.cz> (raw) In-Reply-To: <20191219020337.GA25072@dennisz-mbp.dhcp.thefacebook.com> On Wed, Dec 18, 2019 at 08:03:37PM -0600, Dennis Zhou wrote: > > > This happened also when I deleted everything from the filesystem and ran > > > full balance. > > Also were these both on fresh file systems so it seems reproducible for > you? Yes the filesystem was freshly created before the test. No luck reproducing it, I tried to repeat the steps as before but the timing must make a difference and the numbers always ended up as 0 (bytes) 0 (extents). > > I'll report back if I continue having trouble reproing it. > > I spent the day trying to repro against ext/dzhou-async-discard-v6 > without any luck... I've been running the following: > > $ mkfs.btrfs -f /dev/nvme0n1 > $ mount -t btrfs -o discard=async /dev/nvme0n1 mnt > $ cd mnt > $ bash ../age_btrfs.sh . > > where age_btrfs.sh is from . > > If I delete arbitrary subvolumes, sync, and then run balance: > $ btrfs balance start --full-balance . > It all seems to resolve to 0 after some time. I haven't seen a negative > case on either of my 2 boxes. I've also tried unmounting and then > remounting, deleting and removing more free space items. > > I'm still considering how this can happen. Possibly bad load of free > space cache and then freeing of the block group? Because being off by > just 1 and it not accumulating seems to be a real corner case here. > > Adding asserts in btrfs_discard_update_discardable() might give us > insight to which callsite is responsible for going below 0. Yeah more asserts would be good.
next prev parent reply index Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-14 0:22 Dennis Zhou 2019-12-14 0:22 ` [PATCH 01/22] bitmap: genericize percpu bitmap region iterators Dennis Zhou 2019-12-14 0:22 ` [PATCH 02/22] btrfs: rename DISCARD opt to DISCARD_SYNC Dennis Zhou 2019-12-14 0:22 ` [PATCH 03/22] btrfs: keep track of which extents have been discarded Dennis Zhou 2019-12-14 0:22 ` [PATCH 04/22] btrfs: keep track of cleanliness of the bitmap Dennis Zhou 2019-12-14 0:22 ` [PATCH 05/22] btrfs: add the beginning of async discard, discard workqueue Dennis Zhou 2019-12-14 0:22 ` [PATCH 06/22] btrfs: handle empty block_group removal Dennis Zhou 2019-12-14 0:22 ` [PATCH 07/22] btrfs: discard one region at a time in async discard Dennis Zhou 2019-12-14 0:22 ` [PATCH 08/22] btrfs: add removal calls for sysfs debug/ Dennis Zhou 2019-12-18 11:45 ` Anand Jain 2019-12-14 0:22 ` [PATCH 09/22] btrfs: make UUID/debug have its own kobject Dennis Zhou 2019-12-18 11:45 ` Anand Jain 2019-12-14 0:22 ` [PATCH 10/22] btrfs: add discard sysfs directory Dennis Zhou 2019-12-18 11:45 ` Anand Jain 2019-12-14 0:22 ` [PATCH 11/22] btrfs: track discardable extents for async discard Dennis Zhou 2019-12-14 0:22 ` [PATCH 12/22] btrfs: keep track of discardable_bytes Dennis Zhou 2019-12-14 0:22 ` [PATCH 13/22] btrfs: calculate discard delay based on number of extents Dennis Zhou 2019-12-30 16:50 ` David Sterba 2020-01-02 16:45 ` Dennis Zhou 2019-12-14 0:22 ` [PATCH 14/22] btrfs: add bps discard rate limit Dennis Zhou 2019-12-30 17:58 ` David Sterba 2020-01-02 16:46 ` Dennis Zhou 2019-12-14 0:22 ` [PATCH 15/22] btrfs: limit max discard size for async discard Dennis Zhou 2019-12-30 18:00 ` David Sterba 2019-12-30 18:08 ` David Sterba 2020-01-02 16:48 ` Dennis Zhou 2019-12-14 0:22 ` [PATCH 16/22] btrfs: make max async discard size tunable Dennis Zhou 2019-12-30 18:05 ` David Sterba 2020-01-02 16:50 ` Dennis Zhou 2019-12-14 0:22 ` [PATCH 17/22] btrfs: have multiple discard lists Dennis Zhou 2019-12-14 0:22 ` [PATCH 18/22] btrfs: only keep track of data extents for async discard Dennis Zhou 2019-12-30 17:39 ` David Sterba 2020-01-02 16:55 ` Dennis Zhou 2019-12-14 0:22 ` [PATCH 19/22] btrfs: keep track of discard reuse stats Dennis Zhou 2019-12-30 17:33 ` David Sterba 2020-01-02 16:57 ` Dennis Zhou 2019-12-14 0:22 ` [PATCH 20/22] btrfs: add async discard header Dennis Zhou 2019-12-14 0:22 ` [PATCH 21/22] btrfs: increase the metadata allowance for the free_space_cache Dennis Zhou 2019-12-14 0:22 ` [PATCH 22/22] btrfs: make smaller extents more likely to go into bitmaps Dennis Zhou 2019-12-17 14:55 ` [PATCH v6 00/22] btrfs: async discard support David Sterba 2019-12-18 0:06 ` Dennis Zhou 2019-12-19 2:03 ` Dennis Zhou 2019-12-19 20:06 ` David Sterba [this message] 2019-12-19 21:22 ` Dennis Zhou 2019-12-19 20:34 ` David Sterba 2019-12-19 21:17 ` Dennis Zhou 2019-12-30 18:13 ` David Sterba 2019-12-30 18:49 ` Dennis Zhou 2020-01-02 13:22 ` David Sterba
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