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Date:   Mon, 7 Dec 2020 19:36:09 +0100
From:   Greg KH <greg@kroah.com>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Daejun Park <daejun7.park@samsung.com>,
        "avri.altman@wdc.com" <avri.altman@wdc.com>,
        "jejb@linux.ibm.com" <jejb@linux.ibm.com>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
        "beanhuo@micron.com" <beanhuo@micron.com>,
        "stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
        "cang@codeaurora.org" <cang@codeaurora.org>,
        "bvanassche@acm.org" <bvanassche@acm.org>,
        "tomas.winkler@intel.com" <tomas.winkler@intel.com>,
        ALIM AKHTAR <alim.akhtar@samsung.com>,
        "gregkh@google.com" <gregkh@google.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Sang-yoon Oh <sangyoon.oh@samsung.com>,
        Sung-Jun Park <sungjun07.park@samsung.com>,
        yongmyung lee <ymhungry.lee@samsung.com>,
        Jinyoung CHOI <j-young.choi@samsung.com>,
        Adel Choi <adel.choi@samsung.com>,
        BoRam Shin <boram.shin@samsung.com>,
        SEUNGUK SHIN <seunguk.shin@samsung.com>
Subject: Re: [PATCH v13 0/3] scsi: ufs: Add Host Performance Booster Support
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On Mon, Dec 07, 2020 at 07:35:03PM +0100, Greg KH wrote:
> On Mon, Dec 07, 2020 at 06:26:03PM +0000, Christoph Hellwig wrote:
> > On Mon, Dec 07, 2020 at 07:23:12PM +0100, Greg KH wrote:
> > > What "real workload" test can be run on this to help show if it is
> > > useful or not?  These vendors seem to think it helps for some reason,
> > > otherwise they wouldn't have added it to their silicon :)
> > > 
> > > Should they run fio?  If so, any hints on a config that would be good to
> > > show any performance increases?
> > 
> > A real actual workload that matters.  Then again that was Martins
> > request to even justify it.  I don't think the broken addressing that
> > breaks a whole in the SCSI addressing has absolutely not business being
> > supported in Linux ever.  The vendors should have thought about the
> > design before committing transistors to something that fundamentally
> > does not make sense.
> 
> So "time to boot an android system with this enabled and disabled" would
> be a valid workload, right?  I'm guessing that's what the vendors here
> actually care about, otherwise there is no real stress-test on a UFS
> system that I know of.

Oh, and "supporting stupid hardware specs" is what we do here all the
time, you know that :)

If someone is foolish enough to build it, we usually have to support the
thing, especially if someone else here is willing to do that.  I don't
see where the addressing is "broken", which patch causes that to happen?

thanks,

greg k-h