linux-kernel - RE: [PATCH 3/8] scsi: ufshpb: Add region's reads counter

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Date:   Mon, 1 Feb 2021 07:12:53 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     "daejun7.park@...sung.com" <daejun7.park@...sung.com>,
        "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Bart Van Assche <bvanassche@....org>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        ALIM AKHTAR <alim.akhtar@...sung.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        Zang Leigang <zangleigang@...ilicon.com>,
        Avi Shchislowski <Avi.Shchislowski@....com>,
        Bean Huo <beanhuo@...ron.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>
Subject: RE: [PATCH 3/8] scsi: ufshpb: Add region's reads counter

> > +#define WORK_PENDING 0
> > +#define ACTIVATION_THRSHLD 4 /* 4 IOs */
> Rather than fixing it with macro, how about using sysfs and make it
> configurable?
Yes.
I will add a patch making all the logic configurable.
As all those are hpb-related parameters, I think module parameters are more adequate.


> 
> > @@ -306,12 +325,39 @@ void 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 (ufshpb_mode == HPB_HOST_CONTROL)
> > +                     atomic64_set(&rgn->reads, 0);
> > +
> >               return;
> >       }
> >
> > +     if (ufshpb_mode == HPB_HOST_CONTROL)
> > +             reads = atomic64_inc_return(&rgn->reads);
> > +
> >       if (!ufshpb_is_support_chunk(transfer_len))
> >               return; <- *this*
> >
> > +     if (ufshpb_mode == HPB_HOST_CONTROL) {
> > +             /*
> > +              * in host control mode, reads are the main source for
> > +              * activation trials.
> > +              */
> > +             if (reads == ACTIVATION_THRSHLD) {
> If the chunk size is not supported, we can not active this region
> permanently. It may be returned before get this statement.
Yes.
I already noticed that replying to Greg.
Fixed that when I dropped the use of atomic variables.
 
> 
> > diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> > index 8a34b0f42754..b0e78728af38 100644
> > --- a/drivers/scsi/ufs/ufshpb.h
> > +++ b/drivers/scsi/ufs/ufshpb.h
> > @@ -115,6 +115,9 @@ struct ufshpb_region {
> >       /* below information is used by lru */
> >       struct list_head list_lru_rgn;
> >       unsigned long rgn_flags;
> > +
> > +     /* region reads - for host mode */
> > +     atomic64_t reads;
> I think 32 bits are suitable, because it is normalized by worker on every
> specific time.
Done.