kernel/linux.git/drivers/md/bcache/util.h, branch v6.18.21

Revert "bcache: remove heap-related macros and switch to generic min_heap"

2025-06-20T03:48:03+00:00

This reverts commit 866898efbb25bb44fd42848318e46db9e785973a. The generic bottom-up min_heap implementation causes performance regression in invalidate_buckets_lru(), a hot path in bcache. Before the cache is fully populated, new_bucket_prio() often returns zero, leading to many equal comparisons. In such cases, bottom-up sift_down performs up to 2 * log2(n) comparisons, while the original top-down approach completes with just O() comparisons, resulting in a measurable performance gap. The performance degradation is further worsened by the non-inlined min_heap API functions introduced in commit 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions"), adding function call overhead to this critical path. As reported by Robert, bcache now suffers from latency spikes, with P100 (max) latency increasing from 600 ms to 2.4 seconds every 5 minutes. These regressions degrade bcache's effectiveness as a low-latency cache layer and lead to frequent timeouts and application stalls in production environments. This revert aims to restore bcache's original low-latency behavior. Link: https://lore.kernel.org/lkml/CAJhEC05+0S69z+3+FB2Cd0hD+pCRyWTKLEOsc8BOmH73p1m+KQ@mail.gmail.com Link: https://lkml.kernel.org/r/20250614202353.1632957-3-visitorckw@gmail.com Fixes: 866898efbb25 ("bcache: remove heap-related macros and switch to generic min_heap") Fixes: 92a8b224b833 ("lib/min_heap: introduce non-inline versions of min heap API functions") Signed-off-by: Kuan-Wei Chiu Reported-by: Robert Pang Closes: https://lore.kernel.org/linux-bcache/CAJhEC06F_AtrPgw2-7CvCqZgeStgCtitbD-ryuPpXQA-JG5XXw@mail.gmail.com Acked-by: Coly Li Cc: Ching-Chun (Jim) Huang Cc: Kent Overstreet Cc: Signed-off-by: Andrew Morton

bcache: remove heap-related macros and switch to generic min_heap

2024-06-25T05:25:00+00:00

Drop the heap-related macros from bcache and replacing them with the generic min_heap implementation from include/linux. By doing so, code readability is improved by using functions instead of macros. Moreover, the min_heap implementation in include/linux adopts a bottom-up variation compared to the textbook version currently used in bcache. This bottom-up variation allows for approximately 50% reduction in the number of comparison operations during heap siftdown, without changing the number of swaps, thus making it more efficient. Link: https://lkml.kernel.org/ioyfizrzq7w7mjrqcadtzsfgpuntowtjdw5pgn4qhvsdp4mqqg@nrlek5vmisbu Link: https://lkml.kernel.org/r/20240524152958.919343-16-visitorckw@gmail.com Signed-off-by: Kuan-Wei Chiu Reviewed-by: Ian Rogers Acked-by: Coly Li Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Bagas Sanjaya Cc: Brian Foster Cc: Ching-Chun (Jim) Huang Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kent Overstreet Cc: Mark Rutland Cc: Matthew Sakai Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Randy Dunlap Signed-off-by: Andrew Morton

bcache: move closures to lib/

2023-10-19T18:47:33+00:00

Prep work for bcachefs - being a fork of bcache it also uses closures Signed-off-by: Kent Overstreet Acked-by: Coly Li Reviewed-by: Randy Dunlap

Merge tag 'for-5.16/bdev-size-2021-10-29' of git://git.kernel.dk/linux-block

2021-11-01T16:50:37+00:00

Pull bdev size cleanups from Jens Axboe: "Clean up the bdev size handling with new bdev_nr_bytes() helper" * tag 'for-5.16/bdev-size-2021-10-29' of git://git.kernel.dk/linux-block: (34 commits) partitions/ibm: use bdev_nr_sectors instead of open coding it partitions/efi: use bdev_nr_bytes instead of open coding it block/ioctl: use bdev_nr_sectors and bdev_nr_bytes block: cache inode size in bdev udf: use sb_bdev_nr_blocks reiserfs: use sb_bdev_nr_blocks ntfs: use sb_bdev_nr_blocks jfs: use sb_bdev_nr_blocks ext4: use sb_bdev_nr_blocks block: add a sb_bdev_nr_blocks helper block: use bdev_nr_bytes instead of open coding it in blkdev_fallocate squashfs: use bdev_nr_bytes instead of open coding it reiserfs: use bdev_nr_bytes instead of open coding it pstore/blk: use bdev_nr_bytes instead of open coding it ntfs3: use bdev_nr_bytes instead of open coding it nilfs2: use bdev_nr_bytes instead of open coding it nfs/blocklayout: use bdev_nr_bytes instead of open coding it jfs: use bdev_nr_bytes instead of open coding it hfsplus: use bdev_nr_sectors instead of open coding it hfs: use bdev_nr_sectors instead of open coding it ...

bcache: replace snprintf in show functions with sysfs_emit

2021-10-29T12:43:21+00:00

coccicheck complains about the use of snprintf() in sysfs show functions. Fix the following coccicheck warning: drivers/md/bcache/sysfs.h:54:12-20: WARNING: use scnprintf or sprintf. Implement sysfs_print() by sysfs_emit() and remove snprint() since no one uses it any more. Suggested-by: Coly Li Signed-off-by: Qing Wang Signed-off-by: Coly Li Link: https://lore.kernel.org/r/20211029060930.119923-3-colyli@suse.de Signed-off-by: Jens Axboe

bcache: remove bch_crc64_update

2021-10-20T14:40:54+00:00

bch_crc64_update is an entirely pointless wrapper around crc64_be. Signed-off-by: Christoph Hellwig Signed-off-by: Coly Li Link: https://lore.kernel.org/r/20211020143812.6403-9-colyli@suse.de Signed-off-by: Jens Axboe

bcache: remove bdev_sectors

2021-10-18T20:43:22+00:00

Use the equivalent block layer helper instead. Signed-off-by: Christoph Hellwig Reviewed-by: Kees Cook Reviewed-by: Chaitanya Kulkarni Acked-by: Coly Li Link: https://lore.kernel.org/r/20211018101130.1838532-4-hch@lst.de Signed-off-by: Jens Axboe

block: move some macros to blkdev.h

2021-08-12T01:40:28+00:00

Move them (PAGE_SECTORS_SHIFT, PAGE_SECTORS and SECTOR_MASK) to the generic header file to remove redundancy. Signed-off-by: Guoqing Jiang Link: https://lore.kernel.org/r/20210721025315.1729118-1-guoqing.jiang@linux.dev Signed-off-by: Jens Axboe

md: bcache: avoid -Wempty-body warnings

2021-04-11T14:37:56+00:00

building with 'make W=1' shows a harmless warning for each user of the EBUG_ON() macro: drivers/md/bcache/bset.c: In function 'bch_btree_sort_partial': drivers/md/bcache/util.h:30:55: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body] 30 | #define EBUG_ON(cond) do { if (cond); } while (0) | ^ drivers/md/bcache/bset.c:1312:9: note: in expansion of macro 'EBUG_ON' 1312 | EBUG_ON(oldsize >= 0 && bch_count_data(b) != oldsize); | ^~~~~~~ Reword the macro slightly to avoid the warning. Signed-off-by: Arnd Bergmann Signed-off-by: Coly Li Link: https://lore.kernel.org/r/20210411134316.80274-5-colyli@suse.de Signed-off-by: Jens Axboe

bcache: Revert "bcache: fix high CPU occupancy during journal"

2019-06-28T13:39:17+00:00

This reverts commit c4dc2497d50d9c6fb16aa0d07b6a14f3b2adb1e0. This patch enlarges a race between normal btree flush code path and flush_btree_write(), which causes deadlock when journal space is exhausted. Reverts this patch makes the race window from 128 btree nodes to only 1 btree nodes. Fixes: c4dc2497d50d ("bcache: fix high CPU occupancy during journal") Signed-off-by: Coly Li Cc: stable@vger.kernel.org Cc: Tang Junhui Signed-off-by: Jens Axboe