From: David Sterba <email@example.com> To: Dennis Zhou <firstname.lastname@example.org> Cc: David Sterba <email@example.com>, Chris Mason <firstname.lastname@example.org>, Josef Bacik <email@example.com>, Omar Sandoval <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org Subject: Re: [PATCH v6 00/22] btrfs: async discard support Date: Tue, 17 Dec 2019 15:55:41 +0100 Message-ID: <20191217145541.GE3929@suse.cz> (raw) In-Reply-To: <email@example.com> On Fri, Dec 13, 2019 at 04:22:09PM -0800, Dennis Zhou wrote: > Hello, > > Dave reported a lockdep issue . I'm a bit surprised as I can't repro > it, but it obviously is right. I believe I fixed the issue by moving the > fully trimmed check outside of the block_group lock. I mistakingly > thought the btrfs_block_group lock subsumed btrfs_free_space_ctl > tree_lock. This clearly isn't the case. > > Changes in v6: > - Move the fully trimmed check outside of the block_group lock. v6 passed fstests, with some weird test failures that don't seem to be related to the patchset. Meanwhile I did manual test how the discard behaves. The workload was a series of linux git checkouts of various release tags (ie. this should provide some freed extents and coalesce them eventually to get larger chunks to discard), then a simple large file copy, sync, remove, sync. The discards going down to the device were followin the maximum default size (64M) but I observed that only one range was discarded per 10 seconds, while the other stats there are many more extents to discard. For the large file it took like 5-10 cycles to send all the trimmed ranges, the discardable_extents decreased by one each time until it reached ... -1. At this point the discardable bytes were -16384, so thre's some accounting problem. This happened also when I deleted everything from the filesystem and ran full balance. Regarding the slow io submission, I tried to increase the iops value, default was 10, but 100 and 1000 made no change. Increasing the maximum discard request size to 128M worked (when there was such long extent ready). I was expecting a burst of like 4 consecutive IOs after a 600MB file is deleted. I did not try to tweak bps_limit because there was nothing to limit. So this is something to fix but otherwise the patchset seems to be ok for adding to misc-next. Due to the timing of the end of the year and that we're already at rc2, this will be the main feature in 5.6.
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 ` David Sterba [this message] 2019-12-18 0:06 ` [PATCH v6 00/22] btrfs: async discard support Dennis Zhou 2019-12-19 2:03 ` Dennis Zhou 2019-12-19 20:06 ` David Sterba 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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