From e4ca3932ae90a61c5d0252535f0bc15ce031a457 Mon Sep 17 00:00:00 2001 From: Boris Burkov Date: Fri, 2 Feb 2024 11:54:33 -0800 Subject: btrfs: periodic block_group reclaim We currently employ a edge-triggered block group reclaim strategy which marks block groups for reclaim as they free down past a threshold. With a dynamic threshold, this is worse than doing it in a level-triggered fashion periodically. That is because the reclaim itself happens periodically, so the threshold at that point in time is what really matters, not the threshold at freeing time. If we mark the reclaim in a big pass, then sort by usage and do reclaim, we also benefit from a negative feedback loop preventing unnecessary reclaims as we crunch through the "best" candidates. Since this is quite a different model, it requires some additional support. The edge triggered reclaim has a good heuristic for not reclaiming fresh block groups, so we need to replace that with a typical GC sweep mark which skips block groups that have seen an allocation since the last sweep. Reviewed-by: Josef Bacik Signed-off-by: Boris Burkov Signed-off-by: David Sterba --- fs/btrfs/sysfs.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'fs/btrfs/sysfs.c') diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 360d6093476f..c58cea0da597 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -973,6 +973,39 @@ BTRFS_ATTR_RW(space_info, dynamic_reclaim, btrfs_sinfo_dynamic_reclaim_show, btrfs_sinfo_dynamic_reclaim_store); +static ssize_t btrfs_sinfo_periodic_reclaim_show(struct kobject *kobj, + struct kobj_attribute *a, + char *buf) +{ + struct btrfs_space_info *space_info = to_space_info(kobj); + + return sysfs_emit(buf, "%d\n", READ_ONCE(space_info->periodic_reclaim)); +} + +static ssize_t btrfs_sinfo_periodic_reclaim_store(struct kobject *kobj, + struct kobj_attribute *a, + const char *buf, size_t len) +{ + struct btrfs_space_info *space_info = to_space_info(kobj); + int periodic_reclaim; + int ret; + + ret = kstrtoint(buf, 10, &periodic_reclaim); + if (ret) + return ret; + + if (periodic_reclaim < 0) + return -EINVAL; + + WRITE_ONCE(space_info->periodic_reclaim, periodic_reclaim != 0); + + return len; +} + +BTRFS_ATTR_RW(space_info, periodic_reclaim, + btrfs_sinfo_periodic_reclaim_show, + btrfs_sinfo_periodic_reclaim_store); + /* * Allocation information about block group types. * @@ -996,6 +1029,7 @@ static struct attribute *space_info_attrs[] = { BTRFS_ATTR_PTR(space_info, reclaim_count), BTRFS_ATTR_PTR(space_info, reclaim_bytes), BTRFS_ATTR_PTR(space_info, reclaim_errors), + BTRFS_ATTR_PTR(space_info, periodic_reclaim), #ifdef CONFIG_BTRFS_DEBUG BTRFS_ATTR_PTR(space_info, force_chunk_alloc), #endif -- cgit