RE: [PATCH v4 7/9] scsi: ufshpb: Add "Cold" regions timer

From: Daejun Park <daejun7.park@samsung.com>
To: "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	Bart Van Assche <bvanassche@acm.org>,
	yongmyung lee <ymhungry.lee@samsung.com>,
	Daejun Park <daejun7.park@samsung.com>,
	ALIM AKHTAR <alim.akhtar@samsung.com>,
	"asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
	Zang Leigang <zangleigang@hisilicon.com>,
	Avi Shchislowski <avi.shchislowski@wdc.com>,
	Bean Huo <beanhuo@micron.com>,
	"cang@codeaurora.org" <cang@codeaurora.org>,
	"stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
	Avri Altman <avri.altman@wdc.com>
Subject: RE: [PATCH v4 7/9] scsi: ufshpb: Add "Cold" regions timer
Date: Tue, 02 Mar 2021 17:26:28 +0900	[thread overview]
Message-ID: <878274034.81614673683390.JavaMail.epsvc@epcpadp4> (raw)
In-Reply-To: <20210226083300.30934-8-avri.altman@wdc.com>

Hi Avri,

> +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);
> +
> +        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(rgn, &lru_info->lh_lru_rgn, list_lru_rgn) {
> +                bool timedout = ktime_after(ktime_get(), rgn->read_timeout);
> +
> +                if (timedout) {

It is important not just to check the timeout, but how much time has passed.
If the time exceeded is twice the threshold, the read_timeout_expiries
value should be reduced by 2 instead of 1.

> +                        rgn->read_timeout_expiries--;

Thanks,
Daejun