Messages in this thread | | | Date | Thu, 18 May 2023 17:27:32 +0800 | Subject | Re: [PATCH v2 08/10] maple_tree: Rework mas_wr_slot_store() to be cleaner and more efficient. | From | Peng Zhang <> |
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在 2023/5/18 06:48, Liam R. Howlett 写道: > * Peng Zhang <zhangpeng.00@bytedance.com> [230517 04:59]: >> The code of mas_wr_slot_store() is messy, make it clearer and concise, >> and add comments. In addition, get whether the two gaps are empty to >> avoid calling mas_update_gap() all the time. >> >> Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com> >> --- >> lib/maple_tree.c | 59 ++++++++++++++++++++---------------------------- >> 1 file changed, 24 insertions(+), 35 deletions(-) >> >> diff --git a/lib/maple_tree.c b/lib/maple_tree.c >> index bbe4c6f2858c..25a8b7d5d598 100644 >> --- a/lib/maple_tree.c >> +++ b/lib/maple_tree.c >> @@ -4200,49 +4200,38 @@ static inline bool mas_wr_node_store(struct ma_wr_state *wr_mas) >> static inline bool mas_wr_slot_store(struct ma_wr_state *wr_mas) >> { >> struct ma_state *mas = wr_mas->mas; >> - unsigned long lmax; /* Logical max. */ >> unsigned char offset = mas->offset; >> + unsigned char offset_end = wr_mas->offset_end; >> + unsigned long lmax = wr_mas->end_piv; /* Logical max. */ >> + bool gap = false; >> >> - if ((wr_mas->r_max > mas->last) && ((wr_mas->r_min != mas->index) || >> - (offset != wr_mas->node_end))) >> + if (offset_end - offset != 1) >> return false; >> >> - if (offset == wr_mas->node_end - 1) >> - lmax = mas->max; >> - else >> - lmax = wr_mas->pivots[offset + 1]; >> - >> - /* going to overwrite too many slots. */ >> - if (lmax < mas->last) >> - return false; >> - >> - if (wr_mas->r_min == mas->index) { >> - /* overwriting two or more ranges with one. */ >> - if (lmax == mas->last) >> - return false; >> - >> - /* Overwriting all of offset and a portion of offset + 1. */ >> + if (mas->index == wr_mas->r_min && mas->last < lmax) { >> + /* Overwriting the range and over a part of the next range. */ >> + gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset); >> + gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset + 1); >> rcu_assign_pointer(wr_mas->slots[offset], wr_mas->entry); >> wr_mas->pivots[offset] = mas->last; >> - goto done; >> - } >> - >> - /* Doesn't end on the next range end. */ >> - if (lmax != mas->last) >> + } else if (mas->index > wr_mas->r_min && mas->last == lmax) { >> + /* Overwriting a part of the range and over the next range */ >> + gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset); >> + gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset + 1); >> + rcu_assign_pointer(wr_mas->slots[offset + 1], wr_mas->entry); >> + wr_mas->pivots[offset] = mas->index - 1; >> + mas->offset++; /* Keep mas accurate. */ >> + } else { >> return false; > > Again here, I think you have already verified this will be a slot store > by offset_end - offset == 1 and new_end == wr_mas->node_end. > > The checking of the slots for the gap could be moved outside the > statements. WDYT? Yes, I'll address this in v3. Thanks. > >> + } >> >> - /* Overwriting a portion of offset and all of offset + 1 */ >> - if ((offset + 1 < mt_pivots[wr_mas->type]) && >> - (wr_mas->entry || wr_mas->pivots[offset + 1])) >> - wr_mas->pivots[offset + 1] = mas->last; >> - >> - rcu_assign_pointer(wr_mas->slots[offset + 1], wr_mas->entry); >> - wr_mas->pivots[offset] = mas->index - 1; >> - mas->offset++; /* Keep mas accurate. */ >> - >> -done: >> trace_ma_write(__func__, mas, 0, wr_mas->entry); >> - mas_update_gap(mas); >> + /* >> + * Only update gap when the new entry is empty or there is an empty >> + * entry in the original two ranges. >> + */ >> + if (!wr_mas->entry || gap) >> + mas_update_gap(mas); >> return true; >> } >> >> @@ -4396,7 +4385,7 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas) >> if (new_end == wr_mas->node_end + 1 && mas_wr_append(wr_mas)) >> return; >> >> - if ((wr_mas->offset_end - mas->offset <= 1) && mas_wr_slot_store(wr_mas)) >> + if (new_end == wr_mas->node_end && mas_wr_slot_store(wr_mas)) >> return; >> else if (mas_wr_node_store(wr_mas)) >> return; >> -- >> 2.20.1 >>
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