on 4/4/2024 10:19 PM, Jan Kara wrote:
> On Wed 27-03-24 05:38:22, Kemeng Shi wrote:
>> Use correct criteria name instead stale integer number in comment
>>
>> Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
>
> Looks good. But since the symbolic names already have CR prefix, we
> probably don't have to write e.g.:
>
> /* Large fragment size list lookup succeeded at least once for cr =
> * CR_POWER2_ALIGNED */
>
> But we can write directly:
>
> /* Large fragment size list lookup succeeded at least once for
> * CR_POWER2_ALIGNED */
Sure, will do it in next version. Thanks.
Kemeng
>
> Honza
>
>> ---
>> fs/ext4/ext4.h | 15 ++++++++++++---
>> fs/ext4/mballoc.c | 14 ++++++++------
>> fs/ext4/mballoc.h | 4 ++--
>> 3 files changed, 22 insertions(+), 11 deletions(-)
>>
>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
>> index 023571f8dd1b..9b90013c59a3 100644
>> --- a/fs/ext4/ext4.h
>> +++ b/fs/ext4/ext4.h
>> @@ -213,11 +213,20 @@ enum criteria {
>> #define EXT4_MB_USE_RESERVED 0x2000
>> /* Do strict check for free blocks while retrying block allocation */
>> #define EXT4_MB_STRICT_CHECK 0x4000
>> -/* Large fragment size list lookup succeeded at least once for cr = 0 */
>> +/*
>> + * Large fragment size list lookup succeeded at least once for cr =
>> + * CR_POWER2_ALIGNED
>> + */
>> #define EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED 0x8000
>> -/* Avg fragment size rb tree lookup succeeded at least once for cr = 1 */
>> +/*
>> + * Avg fragment size rb tree lookup succeeded at least once for cr =
>> + * CR_GOAL_LEN_FAST
>> + */
>> #define EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED 0x00010000
>> -/* Avg fragment size rb tree lookup succeeded at least once for cr = 1.5 */
>> +/*
>> + * Avg fragment size rb tree lookup succeeded at least once for cr =
>> + * CR_BEST_AVAIL_LEN
>> + */
>> #define EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED 0x00020000
>>
>> struct ext4_allocation_request {
>> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
>> index 62d468379722..0f8a34513bf6 100644
>> --- a/fs/ext4/mballoc.c
>> +++ b/fs/ext4/mballoc.c
>> @@ -1131,8 +1131,9 @@ static void ext4_mb_choose_next_group(struct ext4_allocation_context *ac,
>> ext4_mb_choose_next_group_best_avail(ac, new_cr, group);
>> } else {
>> /*
>> - * TODO: For CR=2, we can arrange groups in an rb tree sorted by
>> - * bb_free. But until that happens, we should never come here.
>> + * TODO: For CR=CR_GOAL_LEN_SLOW, we can arrange groups in an
>> + * rb tree sorted by bb_free. But until that happens, we should
>> + * never come here.
>> */
>> WARN_ON(1);
>> }
>> @@ -3444,10 +3445,11 @@ static int ext4_mb_init_backend(struct super_block *sb)
>> }
>> if (sbi->s_mb_prefetch > ext4_get_groups_count(sb))
>> sbi->s_mb_prefetch = ext4_get_groups_count(sb);
>> - /* now many real IOs to prefetch within a single allocation at cr=0
>> - * given cr=0 is an CPU-related optimization we shouldn't try to
>> - * load too many groups, at some point we should start to use what
>> - * we've got in memory.
>> + /*
>> + * now many real IOs to prefetch within a single allocation at
>> + * cr=CR_POWER2_ALIGNED. Given cr=CR_POWER2_ALIGNED is an CPU-related
>> + * optimization we shouldn't try to load too many groups, at some point
>> + * we should start to use what we've got in memory.
>> * with an average random access time 5ms, it'd take a second to get
>> * 200 groups (* N with flex_bg), so let's make this limit 4
>> */
>> diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
>> index 56938532b4ce..042437d8860f 100644
>> --- a/fs/ext4/mballoc.h
>> +++ b/fs/ext4/mballoc.h
>> @@ -187,8 +187,8 @@ struct ext4_allocation_context {
>> struct ext4_free_extent ac_f_ex;
>>
>> /*
>> - * goal len can change in CR1.5, so save the original len. This is
>> - * used while adjusting the PA window and for accounting.
>> + * goal len can change in CR_BEST_AVAIL_LEN, so save the original len.
>> + * This is used while adjusting the PA window and for accounting.
>> */
>> ext4_grpblk_t ac_orig_goal_len;
>>
>> --
>> 2.30.0
>>
