Re: [PATCH 7/8] scsi: ufshpb: Add "Cold" regions timer

Greg KH
2021-01-27T15:28:15Z

On Wed, Jan 27, 2021 at 05:12:16PM +0200, Avri Altman wrote:
> In order not to hang on to “cold” regions, we shall inactivate a
> region that has no READ access for a predefined amount of time -
> READ_TO_MS. For that purpose we shall monitor the active regions list,
> polling it on every POLLING_INTERVAL_MS. On timeout expiry we shall add
> the region to the "to-be-inactivated" list, unless it is clean and did
> not exahust its READ_TO_EXPIRIES - another parameter.
>
> All this does not apply to pinned regions.
>
> Signed-off-by: Avri Altman <avri.altman@wdc.com>
> ---
> drivers/scsi/ufs/ufshpb.c | 75 ++++++++++++++++++++++++++++++++++++++-
> drivers/scsi/ufs/ufshpb.h | 7 ++++
> 2 files changed, 81 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> index cb99b57b4319..482f01c3b3ee 100644
> --- a/drivers/scsi/ufs/ufshpb.c
> +++ b/drivers/scsi/ufs/ufshpb.c
> @@ -18,8 +18,12 @@
>
> #define WORK_PENDING 0
> #define RESET_PENDING 1
> +#define TIMEOUT_WORK_PENDING 2
> #define ACTIVATION_THRSHLD 4 /* 4 IOs */
> #define EVICTION_THRSHLD (ACTIVATION_THRSHLD << 6) /* 256 IOs */
> +#define READ_TO_MS 1000
> +#define READ_TO_EXPIRIES 100
> +#define POLLING_INTERVAL_MS 200
>
> /* memory management */
> static struct kmem_cache *ufshpb_mctx_cache;
> @@ -671,12 +675,69 @@ static int ufshpb_check_srgns_issue_state(struct ufshpb_lu *hpb,
> return 0;
> }
>
> +static void ufshpb_read_to_handler(struct work_struct *work)
> +{
> + struct delayed_work *dwork = to_delayed_work(work);
> + struct ufshpb_lu *hpb;
> + struct victim_select_info *lru_info;
> + struct ufshpb_region *rgn, *next_rgn;
> + unsigned long flags;
> + LIST_HEAD(expired_list);
> +
> + hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
> +
> + if (test_and_set_bit(TIMEOUT_WORK_PENDING, &hpb->work_data_bits))
> + return;
> +
> + spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> +
> + lru_info = &hpb->lru_info;
> +
> + list_for_each_entry_safe(rgn, next_rgn, &lru_info->lh_lru_rgn,
> + list_lru_rgn) {
> + bool timedout = ktime_after(ktime_get(), rgn->read_timeout);
> + bool dirty, expired;
> +
> + if (!timedout)
> + continue;
> +
> + dirty = is_rgn_dirty(rgn);
> + expired = atomic_dec_and_test(&rgn->read_timeout_expiries);
> +
> + if (dirty || expired)
> + list_add(&rgn->list_expired_rgn, &expired_list);
> + else
> + rgn->read_timeout = ktime_add_ms(ktime_get(),
> + READ_TO_MS);
> + }
> +
> + spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
> +
> + list_for_each_entry_safe(rgn, next_rgn, &expired_list,
> + list_expired_rgn) {
> + list_del_init(&rgn->list_expired_rgn);
> + spin_lock_irqsave(&hpb->rsp_list_lock, flags);
> + ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
> + hpb->stats.rb_inactive_cnt++;
> + spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> + }
> +
> + clear_bit(TIMEOUT_WORK_PENDING, &hpb->work_data_bits);
> +
> + schedule_delayed_work(&hpb->ufshpb_read_to_work,
> + msecs_to_jiffies(POLLING_INTERVAL_MS));
> +}
> +
> static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
> - struct ufshpb_region *rgn)
> + struct ufshpb_region *rgn)
> {
> rgn->rgn_state = HPB_RGN_ACTIVE;
> list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
> atomic_inc(&lru_info->active_cnt);
> + if (ufshpb_mode == HPB_HOST_CONTROL) {
> + rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
> + atomic_set(&rgn->read_timeout_expiries, READ_TO_EXPIRIES);
> + }
> }
>
> static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
> @@ -1404,6 +1465,7 @@ static int ufshpb_alloc_region_tbl(struct ufs_hba *hba, struct ufshpb_lu *hpb)
>
> INIT_LIST_HEAD(&rgn->list_inact_rgn);
> INIT_LIST_HEAD(&rgn->list_lru_rgn);
> + INIT_LIST_HEAD(&rgn->list_expired_rgn);
>
> if (rgn_idx == hpb->rgns_per_lu - 1)
> srgn_cnt = ((hpb->srgns_per_lu - 1) %
> @@ -1536,6 +1598,8 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
> ufshpb_normalization_work_handler);
> INIT_WORK(&hpb->ufshpb_lun_reset_work,
> ufshpb_reset_work_handler);
> + INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
> + ufshpb_read_to_handler);
> }
>
> hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
> @@ -1562,6 +1626,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
>
> ufshpb_stat_init(hpb);
>
> + if (ufshpb_mode == HPB_HOST_CONTROL)
> + schedule_delayed_work(&hpb->ufshpb_read_to_work,
> + msecs_to_jiffies(POLLING_INTERVAL_MS));
> +
> return 0;
>
> release_m_page_cache:
> @@ -1624,6 +1692,7 @@ static void ufshpb_discard_rsp_lists(struct ufshpb_lu *hpb)
> static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
> {
> if (ufshpb_mode == HPB_HOST_CONTROL) {
> + cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
> cancel_work_sync(&hpb->ufshpb_lun_reset_work);
> cancel_work_sync(&hpb->ufshpb_normalization_work);
> }
> @@ -1734,6 +1803,10 @@ void ufshpb_resume(struct ufs_hba *hba)
> continue;
> ufshpb_set_state(hpb, HPB_PRESENT);
> ufshpb_kick_map_work(hpb);
> + if (ufshpb_mode == HPB_HOST_CONTROL)
> + schedule_delayed_work(&hpb->ufshpb_read_to_work,
> + msecs_to_jiffies(POLLING_INTERVAL_MS));
> +
> }
> }
>
> diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> index 4bf77169af00..86c16a4127bd 100644
> --- a/drivers/scsi/ufs/ufshpb.h
> +++ b/drivers/scsi/ufs/ufshpb.h
> @@ -121,6 +121,12 @@ struct ufshpb_region {
>
> /* region reads - for host mode */
> atomic64_t reads;
> +
> + /* region "cold" timer - for host mode */
> + ktime_t read_timeout;
> + atomic_t read_timeout_expiries;

Why does this have to be an atomic when you have a lock to protect this
structure already taken?

thanks,

greg k-h