On 08/10, Chao Yu wrote:
> Previously, discard speed was fixed mostly, and in high usage rate
> device, we will speed up issuing discard, but it doesn't make sense
> that in a non-full filesystem, we still issue discard with slow speed.
Could you please elaborate the problem in more detail? The speed depends
on how many candidates?
Thanks,
>
> Anyway, it comes out undiscarded block makes FTL GC be lower efficient
> and causing high lifetime overhead.
>
> Let's tune discard speed as below:
>
> a. adjust default issue interval:
> original after
> min_interval: 50ms 100ms
> mid_interval: 500ms 1000ms
> max_interval: 60000ms 10000ms
>
> b. if last time we stop issuing discard due to IO interruption of user,
> let's reset all {min,mid,max}_interval to default one.
>
> c. tune {min,mid,max}_interval with below calculation method:
>
> base_interval = default_interval / 10;
> total_interval = default_interval - base_interval;
> interval = base_interval + total_interval * (100 - dev_util) / 100;
>
> For example:
> min_interval (:100ms)
> dev_util (%) interval (ms)
> 0 100
> 10 91
> 20 82
> 30 73
> ...
> 80 28
> 90 19
> 100 10
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> fs/f2fs/f2fs.h | 11 ++++----
> fs/f2fs/segment.c | 64 +++++++++++++++++++++++++++++++++++++----------
> fs/f2fs/segment.h | 9 +++++++
> fs/f2fs/super.c | 2 +-
> 4 files changed, 67 insertions(+), 19 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 273ffdaf4891..a1dd2e1c3cb9 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -185,10 +185,9 @@ enum {
>
> #define MAX_DISCARD_BLOCKS(sbi) BLKS_PER_SEC(sbi)
> #define DEF_MAX_DISCARD_REQUEST 8 /* issue 8 discards per
> round */
> -#define DEF_MIN_DISCARD_ISSUE_TIME 50 /* 50 ms, if exists */
> -#define DEF_MID_DISCARD_ISSUE_TIME 500 /* 500 ms, if device busy */
> -#define DEF_MAX_DISCARD_ISSUE_TIME 60000 /* 60 s, if no candidates */
> -#define DEF_DISCARD_URGENT_UTIL 80 /* do more discard over
> 80% */
> +#define DEF_MIN_DISCARD_ISSUE_TIME 100 /* 100 ms, if exists */
> +#define DEF_MID_DISCARD_ISSUE_TIME 1000 /* 1000 ms, if device busy */
> +#define DEF_MAX_DISCARD_ISSUE_TIME 10000 /* 10000 ms, if no candidates */
> #define DEF_CP_INTERVAL 60 /* 60 secs */
> #define DEF_IDLE_INTERVAL 5 /* 5 secs */
>
> @@ -248,7 +247,8 @@ struct discard_entry {
> };
>
> /* default discard granularity of inner discard thread, unit: block count */
> -#define DEFAULT_DISCARD_GRANULARITY 1
> +#define MID_DISCARD_GRANULARITY 16
> +#define MIN_DISCARD_GRANULARITY 1
>
> /* max discard pend list number */
> #define MAX_PLIST_NUM 512
> @@ -330,6 +330,7 @@ struct discard_cmd_control {
> atomic_t discard_cmd_cnt; /* # of cached cmd count */
> struct rb_root root; /* root of discard rb-tree */
> bool rbtree_check; /* config for consistence check
> */
> + bool io_interrupted; /* last state of io interrupted
> */
> };
>
> /* for the list of fsync inodes, used only during recovery */
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8b52e8dfb12f..9564aaf1f27b 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -968,6 +968,44 @@ static void __check_sit_bitmap(struct f2fs_sb_info *sbi,
> #endif
> }
>
> +static void __adjust_discard_speed(unsigned int *interval,
> + unsigned int def_interval, int dev_util)
> +{
> + unsigned int base_interval, total_interval;
> +
> + base_interval = def_interval / 10;
> + total_interval = def_interval - base_interval;
> +
> + /*
> + * if def_interval = 100, adjusted interval should be in range of
> + * [10, 100].
> + */
> + *interval = base_interval + total_interval * (100 - dev_util) / 100;
> +}
> +
> +static void __tune_discard_policy(struct f2fs_sb_info *sbi,
> + struct discard_policy *dpolicy)
> +{
> + struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
> + int dev_util;
> +
> + if (dcc->io_interrupted) {
> + dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
> + dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
> + dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
> + return;
> + }
> +
> + dev_util = dev_utilization(sbi);
> +
> + __adjust_discard_speed(&dpolicy->min_interval,
> + DEF_MIN_DISCARD_ISSUE_TIME, dev_util);
> + __adjust_discard_speed(&dpolicy->mid_interval,
> + DEF_MID_DISCARD_ISSUE_TIME, dev_util);
> + __adjust_discard_speed(&dpolicy->max_interval,
> + DEF_MAX_DISCARD_ISSUE_TIME, dev_util);
> +}
> +
> static void __init_discard_policy(struct f2fs_sb_info *sbi,
> struct discard_policy *dpolicy,
> int discard_type, unsigned int granularity)
> @@ -982,20 +1020,11 @@ static void __init_discard_policy(struct f2fs_sb_info
> *sbi,
> dpolicy->io_aware_gran = MAX_PLIST_NUM;
>
> if (discard_type == DPOLICY_BG) {
> - dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
> - dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
> - dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
> dpolicy->io_aware = true;
> dpolicy->sync = false;
> dpolicy->ordered = true;
> - if (utilization(sbi) > DEF_DISCARD_URGENT_UTIL) {
> - dpolicy->granularity = 1;
> - dpolicy->max_interval = DEF_MIN_DISCARD_ISSUE_TIME;
> - }
> + __tune_discard_policy(sbi, dpolicy);
> } else if (discard_type == DPOLICY_FORCE) {
> - dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
> - dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
> - dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
> dpolicy->io_aware = false;
> } else if (discard_type == DPOLICY_FSTRIM) {
> dpolicy->io_aware = false;
> @@ -1353,6 +1382,8 @@ static unsigned int __issue_discard_cmd_orderly(struct
> f2fs_sb_info *sbi,
> if (!issued && io_interrupted)
> issued = -1;
>
> + dcc->io_interrupted = io_interrupted;
> +
> return issued;
> }
>
> @@ -1370,7 +1401,7 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
> if (i + 1 < dpolicy->granularity)
> break;
>
> - if (i < DEFAULT_DISCARD_GRANULARITY && dpolicy->ordered)
> + if (i < MID_DISCARD_GRANULARITY && dpolicy->ordered)
> return __issue_discard_cmd_orderly(sbi, dpolicy);
>
> pend_list = &dcc->pend_list[i];
> @@ -1407,6 +1438,8 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
> if (!issued && io_interrupted)
> issued = -1;
>
> + dcc->io_interrupted = io_interrupted;
> +
> return issued;
> }
>
> @@ -1576,7 +1609,11 @@ static int issue_discard_thread(void *data)
> struct f2fs_sb_info *sbi = data;
> struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
> wait_queue_head_t *q = &dcc->discard_wait_queue;
> - struct discard_policy dpolicy;
> + struct discard_policy dpolicy = {
> + .min_interval = DEF_MIN_DISCARD_ISSUE_TIME,
> + .mid_interval = DEF_MID_DISCARD_ISSUE_TIME,
> + .max_interval = DEF_MAX_DISCARD_ISSUE_TIME,
> + };
> unsigned int wait_ms = DEF_MIN_DISCARD_ISSUE_TIME;
> int issued;
>
> @@ -1929,7 +1966,7 @@ static int create_discard_cmd_control(struct
> f2fs_sb_info *sbi)
> if (!dcc)
> return -ENOMEM;
>
> - dcc->discard_granularity = DEFAULT_DISCARD_GRANULARITY;
> + dcc->discard_granularity = MIN_DISCARD_GRANULARITY;
> INIT_LIST_HEAD(&dcc->entry_list);
> for (i = 0; i < MAX_PLIST_NUM; i++)
> INIT_LIST_HEAD(&dcc->pend_list[i]);
> @@ -1945,6 +1982,7 @@ static int create_discard_cmd_control(struct
> f2fs_sb_info *sbi)
> dcc->next_pos = 0;
> dcc->root = RB_ROOT;
> dcc->rbtree_check = false;
> + dcc->io_interrupted = false;
>
> init_waitqueue_head(&dcc->discard_wait_queue);
> SM_I(sbi)->dcc_info = dcc;
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 422b0ceb1eaa..63b4da72cd34 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -616,6 +616,15 @@ static inline int utilization(struct f2fs_sb_info *sbi)
> sbi->user_block_count);
> }
>
> +static inline int dev_utilization(struct f2fs_sb_info *sbi)
> +{
> + unsigned int dev_blks;
> +
> + dev_blks = valid_user_blocks(sbi) + SM_I(sbi)->dcc_info->undiscard_blks;
> + return div_u64((u64)dev_blks * 100,
> + MAIN_SEGS(sbi) << sbi->log_blocks_per_seg);
> +}
> +
> /*
> * Sometimes f2fs may be better to drop out-of-place update policy.
> * And, users can control the policy through sysfs entries.
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index b055f2ea77c5..55ed76daad23 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2862,7 +2862,7 @@ static void f2fs_tuning_parameters(struct f2fs_sb_info
> *sbi)
> /* adjust parameters according to the volume size */
> if (sm_i->main_segments <= SMALL_VOLUME_SEGMENTS) {
> F2FS_OPTION(sbi).alloc_mode = ALLOC_MODE_REUSE;
> - sm_i->dcc_info->discard_granularity = 1;
> + sm_i->dcc_info->discard_granularity = MIN_DISCARD_GRANULARITY;
> sm_i->ipu_policy = 1 << F2FS_IPU_FORCE;
> }
>
> --
> 2.18.0.rc1
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