From: Dennis Zhou <dennis@kernel.org> To: David Sterba <dsterba@suse.com>, Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>, Omar Sandoval <osandov@osandov.com> Cc: kernel-team@fb.com, linux-btrfs@vger.kernel.org, Dennis Zhou <dennis@kernel.org> Subject: [PATCH 15/22] btrfs: limit max discard size for async discard Date: Wed, 20 Nov 2019 16:51:14 -0500 Message-ID: <dfd8963dfba41c6253c6926302b4de106cbeb07e.1574282259.git.dennis@kernel.org> (raw) In-Reply-To: <cover.1574282259.git.dennis@kernel.org> In-Reply-To: <cover.1574282259.git.dennis@kernel.org> Throttle the maximum size of a discard so that we can provide an upper bound for the rate of async discard. While the block layer is able to split discards into the appropriate sized discards, we want to be able to account more accurately the rate at which we are consuming ncq slots as well as limit the upper bound of work for a discard. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> --- fs/btrfs/discard.h | 5 ++++ fs/btrfs/free-space-cache.c | 48 +++++++++++++++++++++++++++---------- 2 files changed, 41 insertions(+), 12 deletions(-) diff --git a/fs/btrfs/discard.h b/fs/btrfs/discard.h index 88f1363aa4e4..e1819f319901 100644 --- a/fs/btrfs/discard.h +++ b/fs/btrfs/discard.h @@ -3,10 +3,15 @@ #ifndef BTRFS_DISCARD_H #define BTRFS_DISCARD_H +#include <linux/sizes.h> + struct btrfs_fs_info; struct btrfs_discard_ctl; struct btrfs_block_group; +/* Discard size limits. */ +#define BTRFS_ASYNC_DISCARD_MAX_SIZE (SZ_64M) + /* List operations. */ void btrfs_add_to_discard_list(struct btrfs_discard_ctl *discard_ctl, struct btrfs_block_group *block_group); diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index c0a08c8df3dd..b03216c550e6 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -3442,19 +3442,40 @@ static int trim_no_bitmap(struct btrfs_block_group *block_group, if (entry->offset >= end) goto out_unlock; - extent_start = entry->offset; - extent_bytes = entry->bytes; - extent_trim_state = entry->trim_state; - start = max(start, extent_start); - bytes = min(extent_start + extent_bytes, end) - start; - if (bytes < minlen) { - spin_unlock(&ctl->tree_lock); - mutex_unlock(&ctl->cache_writeout_mutex); - goto next; - } + if (async) { + start = extent_start = entry->offset; + bytes = extent_bytes = entry->bytes; + extent_trim_state = entry->trim_state; + if (bytes < minlen) { + spin_unlock(&ctl->tree_lock); + mutex_unlock(&ctl->cache_writeout_mutex); + goto next; + } + unlink_free_space(ctl, entry); + if (bytes > BTRFS_ASYNC_DISCARD_MAX_SIZE) { + bytes = extent_bytes = + BTRFS_ASYNC_DISCARD_MAX_SIZE; + entry->offset += BTRFS_ASYNC_DISCARD_MAX_SIZE; + entry->bytes -= BTRFS_ASYNC_DISCARD_MAX_SIZE; + link_free_space(ctl, entry); + } else { + kmem_cache_free(btrfs_free_space_cachep, entry); + } + } else { + extent_start = entry->offset; + extent_bytes = entry->bytes; + extent_trim_state = entry->trim_state; + start = max(start, extent_start); + bytes = min(extent_start + extent_bytes, end) - start; + if (bytes < minlen) { + spin_unlock(&ctl->tree_lock); + mutex_unlock(&ctl->cache_writeout_mutex); + goto next; + } - unlink_free_space(ctl, entry); - kmem_cache_free(btrfs_free_space_cachep, entry); + unlink_free_space(ctl, entry); + kmem_cache_free(btrfs_free_space_cachep, entry); + } spin_unlock(&ctl->tree_lock); trim_entry.start = extent_start; @@ -3619,6 +3640,9 @@ static int trim_bitmaps(struct btrfs_block_group *block_group, goto next; } + if (async && bytes > BTRFS_ASYNC_DISCARD_MAX_SIZE) + bytes = BTRFS_ASYNC_DISCARD_MAX_SIZE; + bitmap_clear_bits(ctl, entry, start, bytes); if (entry->bytes == 0) free_bitmap(ctl, entry); -- 2.17.1
next prev parent reply index Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-11-20 21:50 [PATCH v3 00/22] btrfs: async discard support Dennis Zhou 2019-11-20 21:51 ` [PATCH 01/22] bitmap: genericize percpu bitmap region iterators Dennis Zhou 2019-11-20 21:51 ` [PATCH 02/22] btrfs: rename DISCARD opt to DISCARD_SYNC Dennis Zhou 2019-11-20 21:51 ` [PATCH 03/22] btrfs: keep track of which extents have been discarded 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 2019-11-20 21:51 ` [PATCH 05/22] btrfs: add the beginning of async discard, discard workqueue Dennis Zhou 2019-11-20 21:51 ` [PATCH 06/22] btrfs: handle empty block_group removal Dennis Zhou 2019-11-20 21:51 ` [PATCH 07/22] btrfs: discard one region at a time in async discard Dennis Zhou 2019-11-20 21:51 ` [PATCH 08/22] btrfs: add removal calls for sysfs debug/ Dennis Zhou 2019-11-20 21:51 ` [PATCH 09/22] btrfs: make UUID/debug have its own kobject Dennis Zhou 2019-11-20 21:51 ` [PATCH 10/22] btrfs: add discard sysfs directory Dennis Zhou 2019-11-20 21:51 ` [PATCH 11/22] btrfs: track discardable extents for async discard Dennis Zhou 2019-11-20 21:51 ` [PATCH 12/22] btrfs: keep track of discardable_bytes Dennis Zhou 2019-11-20 21:51 ` [PATCH 13/22] btrfs: calculate discard delay based on number of extents Dennis Zhou 2019-11-20 21:51 ` [PATCH 14/22] btrfs: add bps discard rate limit Dennis Zhou 2019-11-20 21:51 ` Dennis Zhou [this message] 2019-11-20 21:51 ` [PATCH 16/22] btrfs: make max async discard size tunable Dennis Zhou 2019-11-20 21:51 ` [PATCH 17/22] btrfs: have multiple discard lists Dennis Zhou 2019-11-20 21:51 ` [PATCH 18/22] btrfs: only keep track of data extents for async discard Dennis Zhou 2019-11-20 21:51 ` [PATCH 19/22] btrfs: keep track of discard reuse stats Dennis Zhou 2019-11-20 21:51 ` [PATCH 20/22] btrfs: add async discard header Dennis Zhou 2019-11-20 21:51 ` [PATCH 21/22] btrfs: increase the metadata allowance for the free_space_cache Dennis Zhou 2019-11-20 21:51 ` [PATCH 22/22] btrfs: make smaller extents more likely to go into bitmaps Dennis Zhou -- strict thread matches above, loose matches on Subject: below -- 2019-12-14 0:22 [PATCH v6 00/22] btrfs: async discard support 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 2019-12-09 19:45 [PATCH v5 00/22] btrfs: async discard support Dennis Zhou 2019-12-09 19:46 ` [PATCH 15/22] btrfs: limit max discard size 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 15/22] btrfs: limit max discard size for async discard Dennis Zhou 2019-10-23 22:52 [PATCH v2 00/22] btrfs: async discard support Dennis Zhou 2019-10-23 22:53 ` [PATCH 15/22] btrfs: limit max discard size for async discard Dennis Zhou
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