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Date: Mon, 15 Mar 2021 11:16:04 +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 03/10] scsi: ufshpb: Add region's reads counter
Hi Avri,
On 2021-03-02 21:24, Avri Altman wrote:
> In host control mode, reads are the major source of activation trials.
> Keep track of those reads counters, for both active as well inactive
> regions.
>
> We reset the read counter upon write - we are only interested in
> "clean"
> reads. less intuitive however, is that we also reset it upon region's
> deactivation. Region deactivation is often due to the fact that
> eviction took place: a region become active on the expense of another.
> This is happening when the max-active-regions limit has crossed. If we
> don’t reset the counter, we will trigger a lot of trashing of the HPB
> database, since few reads (or even one) to the region that was
> deactivated, will trigger a re-activation trial.
>
> Keep those counters normalized, as we are using those reads as a
> comparative score, to make various decisions.
> If during consecutive normalizations an active region has exhaust its
> reads - inactivate it.
>
> Signed-off-by: Avri Altman <avri.altman@....com>
> ---
> drivers/scsi/ufs/ufshpb.c | 102 ++++++++++++++++++++++++++++++++------
> drivers/scsi/ufs/ufshpb.h | 5 ++
> 2 files changed, 92 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> index 044fec9854a0..a8f8d13af21a 100644
> --- a/drivers/scsi/ufs/ufshpb.c
> +++ b/drivers/scsi/ufs/ufshpb.c
> @@ -16,6 +16,8 @@
> #include "ufshpb.h"
> #include "../sd.h"
>
> +#define ACTIVATION_THRESHOLD 4 /* 4 IOs */
> +
> /* memory management */
> static struct kmem_cache *ufshpb_mctx_cache;
> static mempool_t *ufshpb_mctx_pool;
> @@ -554,6 +556,21 @@ static int ufshpb_issue_pre_req(struct ufshpb_lu
> *hpb, struct scsi_cmnd *cmd,
> return ret;
> }
>
> +static void ufshpb_update_active_info(struct ufshpb_lu *hpb, int
> rgn_idx,
> + int srgn_idx)
> +{
> + struct ufshpb_region *rgn;
> + struct ufshpb_subregion *srgn;
> +
> + rgn = hpb->rgn_tbl + rgn_idx;
> + srgn = rgn->srgn_tbl + srgn_idx;
> +
> + list_del_init(&rgn->list_inact_rgn);
> +
> + if (list_empty(&srgn->list_act_srgn))
> + list_add_tail(&srgn->list_act_srgn, &hpb->lh_act_srgn);
> +}
> +
> /*
> * This function will set up HPB read command using host-side L2P map
> data.
> */
> @@ -600,12 +617,44 @@ int ufshpb_prep(struct ufs_hba *hba, struct
> ufshcd_lrb *lrbp)
> ufshpb_set_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
> transfer_len);
> spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
> +
> + if (hpb->is_hcm) {
> + spin_lock_irqsave(&rgn->rgn_lock, flags);
rgn_lock is never used in IRQ contexts, so no need of irqsave and
irqrestore everywhere, which can impact performance. Please correct
me if I am wrong.
Meanwhile, have you ever initialized the rgn_lock before use it???
Thanks,
Can Guo.
> + rgn->reads = 0;
> + spin_unlock_irqrestore(&rgn->rgn_lock, flags);
> + }
> +
> return 0;
> }
>
> if (!ufshpb_is_support_chunk(hpb, transfer_len))
> return 0;
>
> + if (hpb->is_hcm) {
> + bool activate = false;
> + /*
> + * in host control mode, reads are the main source for
> + * activation trials.
> + */
> + spin_lock_irqsave(&rgn->rgn_lock, flags);
> + rgn->reads++;
> + if (rgn->reads == ACTIVATION_THRESHOLD)
> + activate = true;
> + spin_unlock_irqrestore(&rgn->rgn_lock, flags);
> + if (activate) {
> + spin_lock_irqsave(&hpb->rsp_list_lock, flags);
> + ufshpb_update_active_info(hpb, rgn_idx, srgn_idx);
> + hpb->stats.rb_active_cnt++;
> + spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> + dev_dbg(&hpb->sdev_ufs_lu->sdev_dev,
> + "activate region %d-%d\n", rgn_idx, srgn_idx);
> + }
> +
> + /* keep those counters normalized */
> + if (rgn->reads > hpb->entries_per_srgn)
> + schedule_work(&hpb->ufshpb_normalization_work);
> + }
> +
> spin_lock_irqsave(&hpb->rgn_state_lock, flags);
> if (ufshpb_test_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
> transfer_len)) {
> @@ -745,21 +794,6 @@ static int ufshpb_clear_dirty_bitmap(struct
> ufshpb_lu *hpb,
> return 0;
> }
>
> -static void ufshpb_update_active_info(struct ufshpb_lu *hpb, int
> rgn_idx,
> - int srgn_idx)
> -{
> - struct ufshpb_region *rgn;
> - struct ufshpb_subregion *srgn;
> -
> - rgn = hpb->rgn_tbl + rgn_idx;
> - srgn = rgn->srgn_tbl + srgn_idx;
> -
> - list_del_init(&rgn->list_inact_rgn);
> -
> - if (list_empty(&srgn->list_act_srgn))
> - list_add_tail(&srgn->list_act_srgn, &hpb->lh_act_srgn);
> -}
> -
> static void ufshpb_update_inactive_info(struct ufshpb_lu *hpb, int
> rgn_idx)
> {
> struct ufshpb_region *rgn;
> @@ -1079,6 +1113,14 @@ static void __ufshpb_evict_region(struct
> ufshpb_lu *hpb,
>
> ufshpb_cleanup_lru_info(lru_info, rgn);
>
> + if (hpb->is_hcm) {
> + unsigned long flags;
> +
> + spin_lock_irqsave(&rgn->rgn_lock, flags);
> + rgn->reads = 0;
> + spin_unlock_irqrestore(&rgn->rgn_lock, flags);
> + }
> +
> for_each_sub_region(rgn, srgn_idx, srgn)
> ufshpb_purge_active_subregion(hpb, srgn);
> }
> @@ -1523,6 +1565,31 @@ static void
> ufshpb_run_inactive_region_list(struct ufshpb_lu *hpb)
> spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
> }
>
> +static void ufshpb_normalization_work_handler(struct work_struct
> *work)
> +{
> + struct ufshpb_lu *hpb;
> + int rgn_idx;
> + unsigned long flags;
> +
> + hpb = container_of(work, struct ufshpb_lu,
> ufshpb_normalization_work);
> +
> + for (rgn_idx = 0; rgn_idx < hpb->rgns_per_lu; rgn_idx++) {
> + struct ufshpb_region *rgn = hpb->rgn_tbl + rgn_idx;
> +
> + spin_lock_irqsave(&rgn->rgn_lock, flags);
> + rgn->reads = (rgn->reads >> 1);
> + spin_unlock_irqrestore(&rgn->rgn_lock, flags);
> +
> + if (rgn->rgn_state != HPB_RGN_ACTIVE || rgn->reads)
> + continue;
> +
> + /* if region is active but has no reads - inactivate it */
> + spin_lock(&hpb->rsp_list_lock);
> + ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
> + spin_unlock(&hpb->rsp_list_lock);
> + }
> +}
> +
> static void ufshpb_map_work_handler(struct work_struct *work)
> {
> struct ufshpb_lu *hpb = container_of(work, struct ufshpb_lu,
> map_work);
> @@ -1913,6 +1980,9 @@ static int ufshpb_lu_hpb_init(struct ufs_hba
> *hba, struct ufshpb_lu *hpb)
> INIT_LIST_HEAD(&hpb->list_hpb_lu);
>
> INIT_WORK(&hpb->map_work, ufshpb_map_work_handler);
> + if (hpb->is_hcm)
> + INIT_WORK(&hpb->ufshpb_normalization_work,
> + ufshpb_normalization_work_handler);
>
> hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
> sizeof(struct ufshpb_req), 0, 0, NULL);
> @@ -2012,6 +2082,8 @@ static void ufshpb_discard_rsp_lists(struct
> ufshpb_lu *hpb)
>
> static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
> {
> + if (hpb->is_hcm)
> + cancel_work_sync(&hpb->ufshpb_normalization_work);
> cancel_work_sync(&hpb->map_work);
> }
>
> diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> index 8119b1a3d1e5..bd4308010466 100644
> --- a/drivers/scsi/ufs/ufshpb.h
> +++ b/drivers/scsi/ufs/ufshpb.h
> @@ -121,6 +121,10 @@ struct ufshpb_region {
> struct list_head list_lru_rgn;
> unsigned long rgn_flags;
> #define RGN_FLAG_DIRTY 0
> +
> + /* region reads - for host mode */
> + spinlock_t rgn_lock;
> + unsigned int reads;
> };
>
> #define for_each_sub_region(rgn, i, srgn) \
> @@ -211,6 +215,7 @@ struct ufshpb_lu {
>
> /* for selecting victim */
> struct victim_select_info lru_info;
> + struct work_struct ufshpb_normalization_work;
>
> /* pinned region information */
> u32 lu_pinned_start;
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