[f2fs-dev] [PATCH] f2fs-tools: give 6 sections for overprovision buffer

[Jaegeuk Kim <jaegeuk@kernel.org>]

This addresses high GC cost at runtime.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 include/f2fs_fs.h  | 8 +++++++-
 mkfs/f2fs_format.c | 5 +++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
index fc56396fa358..870a6e4823d2 100644
--- a/include/f2fs_fs.h
+++ b/include/f2fs_fs.h
@@ -1775,6 +1775,12 @@ static inline uint32_t get_reserved(struct f2fs_super_block *sb, double ovp)
 	return round_up(reserved, segs_per_sec) * segs_per_sec;
 }
 
+static inline uint32_t overprovision_segment_buffer(struct f2fs_super_block *sb)
+{
+	/* Give 6 current sections to avoid huge GC overheads. */
+	return 6 * get_sb(segs_per_sec);
+}
+
 static inline double get_best_overprovision(struct f2fs_super_block *sb)
 {
 	double ovp, candidate, end, diff, space;
@@ -1798,7 +1804,7 @@ static inline double get_best_overprovision(struct f2fs_super_block *sb)
 		if (ovp < 0)
 			continue;
 		space = usable_main_segs - max((double)reserved, ovp) -
-					2 * get_sb(segs_per_sec);
+					overprovision_segment_buffer(sb);
 		if (max_space < space) {
 			max_space = space;
 			max_ovp = candidate;
diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
index 8f632f8d74b4..e26a513ed80c 100644
--- a/mkfs/f2fs_format.c
+++ b/mkfs/f2fs_format.c
@@ -778,7 +778,8 @@ static int f2fs_write_check_point_pack(void)
 		 * In non configurable reserved section case, overprovision
 		 * segments are always bigger than two sections.
 		 */
-		if (get_cp(overprov_segment_count) < 2 * get_sb(segs_per_sec)) {
+		if (get_cp(overprov_segment_count) <
+					overprovision_segment_buffer(sb)) {
 			MSG(0, "\tError: Not enough overprovision segments (%u)\n",
 			    get_cp(overprov_segment_count));
 			goto free_cp_payload;
@@ -787,7 +788,7 @@ static int f2fs_write_check_point_pack(void)
 				get_cp(rsvd_segment_count));
 	 } else {
 		set_cp(overprov_segment_count, get_cp(overprov_segment_count) +
-				2 * get_sb(segs_per_sec));
+				overprovision_segment_buffer(sb));
 	 }
 
 	if (f2fs_get_usable_segments(sb) <= get_cp(overprov_segment_count)) {
-- 
2.44.0.478.gd926399ef9-goog



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