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Date: Mon, 15 Mar 2021 17:36:28 +0800
From: Can Guo <cang@...eaurora.org>
To: Avri Altman <avri.altman@....com>
Cc: "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
"Martin K . Petersen" <martin.petersen@...cle.com>,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
gregkh@...uxfoundation.org, Bart Van Assche <bvanassche@....org>,
yongmyung lee <ymhungry.lee@...sung.com>,
Daejun Park <daejun7.park@...sung.com>,
alim.akhtar@...sung.com, asutoshd@...eaurora.org,
Zang Leigang <zangleigang@...ilicon.com>,
Avi Shchislowski <avi.shchislowski@....com>,
Bean Huo <beanhuo@...ron.com>, stanley.chu@...iatek.com
Subject: Re: [PATCH v5 07/10] scsi: ufshpb: Add "Cold" regions timer
On 2021-03-02 21:25, 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 exhaust its READ_TO_EXPIRIES - another parameter.
>
> All this does not apply to pinned regions.
>
> Signed-off-by: Avri Altman <avri.altman@....com>
> ---
> drivers/scsi/ufs/ufshpb.c | 65 +++++++++++++++++++++++++++++++++++++++
> drivers/scsi/ufs/ufshpb.h | 6 ++++
> 2 files changed, 71 insertions(+)
>
> diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> index 0034fa03fdc6..89a930e72cff 100644
> --- a/drivers/scsi/ufs/ufshpb.c
> +++ b/drivers/scsi/ufs/ufshpb.c
> @@ -18,6 +18,9 @@
>
> #define ACTIVATION_THRESHOLD 4 /* 4 IOs */
> #define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 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;
> @@ -1024,12 +1027,61 @@ 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;
> + unsigned long flags;
> + LIST_HEAD(expired_list);
> +
> + hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
> +
> + spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> +
> + lru_info = &hpb->lru_info;
> +
> + list_for_each_entry(rgn, &lru_info->lh_lru_rgn, list_lru_rgn) {
> + bool timedout = ktime_after(ktime_get(), rgn->read_timeout);
> +
> + if (timedout) {
> + rgn->read_timeout_expiries--;
> + if (is_rgn_dirty(rgn) ||
> + rgn->read_timeout_expiries == 0)
> + 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(rgn, &expired_list, list_expired_rgn) {
Here can be problematic - since you don't have the native expired_list
initialized
before use, if above loop did not insert anything to expired_list, it
shall become
a dead loop here.
And, which lock is protecting rgn->list_expired_rgn? If two
read_to_handler works
are running in parallel, one can be inserting it to its expired_list
while another
can be deleting it.
Can Guo.
> + 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);
> + }
> +
> + ufshpb_kick_map_work(hpb);
> +
> + 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)
> {
> 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 (rgn->hpb->is_hcm) {
> + rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
> + rgn->read_timeout_expiries = READ_TO_EXPIRIES;
> + }
> }
>
> static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
> @@ -1813,6 +1865,7 @@ 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) %
> @@ -1834,6 +1887,7 @@ static int ufshpb_alloc_region_tbl(struct
> ufs_hba *hba, struct ufshpb_lu *hpb)
> }
>
> rgn->rgn_flags = 0;
> + rgn->hpb = hpb;
> }
>
> return 0;
> @@ -2053,6 +2107,8 @@ 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",
> @@ -2087,6 +2143,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> *hba, struct ufshpb_lu *hpb)
> ufshpb_stat_init(hpb);
> ufshpb_param_init(hpb);
>
> + if (hpb->is_hcm)
> + schedule_delayed_work(&hpb->ufshpb_read_to_work,
> + msecs_to_jiffies(POLLING_INTERVAL_MS));
> +
> return 0;
>
> release_pre_req_mempool:
> @@ -2154,6 +2214,7 @@ static void ufshpb_discard_rsp_lists(struct
> ufshpb_lu *hpb)
> static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
> {
> if (hpb->is_hcm) {
> + cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
> cancel_work_sync(&hpb->ufshpb_lun_reset_work);
> cancel_work_sync(&hpb->ufshpb_normalization_work);
> }
> @@ -2264,6 +2325,10 @@ void ufshpb_resume(struct ufs_hba *hba)
> continue;
> ufshpb_set_state(hpb, HPB_PRESENT);
> ufshpb_kick_map_work(hpb);
> + if (hpb->is_hcm)
> + 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 37c1b0ea0c0a..b49e9a34267f 100644
> --- a/drivers/scsi/ufs/ufshpb.h
> +++ b/drivers/scsi/ufs/ufshpb.h
> @@ -109,6 +109,7 @@ struct ufshpb_subregion {
> };
>
> struct ufshpb_region {
> + struct ufshpb_lu *hpb;
> struct ufshpb_subregion *srgn_tbl;
> enum HPB_RGN_STATE rgn_state;
> int rgn_idx;
> @@ -126,6 +127,10 @@ struct ufshpb_region {
> /* region reads - for host mode */
> spinlock_t rgn_lock;
> unsigned int reads;
> + /* region "cold" timer - for host mode */
> + ktime_t read_timeout;
> + unsigned int read_timeout_expiries;
> + struct list_head list_expired_rgn;
> };
>
> #define for_each_sub_region(rgn, i, srgn) \
> @@ -219,6 +224,7 @@ struct ufshpb_lu {
> struct victim_select_info lru_info;
> struct work_struct ufshpb_normalization_work;
> struct work_struct ufshpb_lun_reset_work;
> + struct delayed_work ufshpb_read_to_work;
>
> /* pinned region information */
> u32 lu_pinned_start;
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