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Subject: Re: [RFC PATCH v3 0/5] scsi: ufs: Add Host Performance Booster
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Reply-To: daejun7.park@samsung.com
From:   Daejun Park <daejun7.park@samsung.com>
To:     Bean Huo <huobean@gmail.com>,
        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>,
        "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>
CC:     "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>
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Date:   Wed, 01 Jul 2020 09:14:34 +0900
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On Tue, 2020-06-30 at 10:05 +0900, Daejun Park wrote:
> > Hi Bean,
> > > On Mon, 2020-06-29 at 15:15 +0900, Daejun Park wrote:
> > > > > Seems you intentionally ignored to give you comments on my
> > > > > suggestion.
> > > > > let me provide the reason.
> > > > 
> > > > Sorry! I replied to your comment (
> > > > 
> https://protect2.fireeye.com/url?k=be575021-e3854728-be56db6e-0cc47a31cdf8-6c7d0e1e42762b92&q=1&u=https%3A%2F%2Flkml.org%2Flkml%2F2020%2F6%2F15%2F1492
> > > > ),
> > > > but you didn't reply on that. I thought you agreed because you
> > > > didn't
> > > > send
> > > > any more comments.
> > > > 
> > > > 
> > > > > Before submitting your next version patch, please check your
> > > > > L2P
> > > > > mapping HPB reqeust submission logical algorithem. I have did
> > > > 
> > > > We are also reviewing the code that you submitted before.
> > > > It seems to be a performance improvement as it sends a map
> > > > request
> > > > directly.
> > > > 
> > > > > performance comparison testing on 4KB, there are about 13%
> > > > > performance
> > > > > drop. Also the hit count is lower. I don't know if this is
> > > > > related
> > > > > to
> > > > 
> > > > It is interesting that there is actually a performance
> > > > improvement. 
> > > > Could you share the test environment, please? However, I think
> > > > stability is
> > > > important to HPB driver. We have tested our method with the real
> > > > products and
> > > > the HPB 1.0 driver is based on that.
> > > 
> > > I just run fio benchmark tool with --rw=randread, --bs=4kb, --
> > > size=8G/10G/64G/100G. and see what performance diff with the direct
> > > submission approach.
> > 
> > Thanks!
> > 
> > > > After this patch, your approach can be done as an incremental
> > > > patch?
> > > > I would
> > > > like to test the patch that you submitted and verify it.
> > > > 
> > > > > your current work queue scheduling, since you didn't add the
> > > > > timer
> > > > > for
> > > > > each HPB request.
> > > 
> > > Taking into consideration of the HPB 2.0, can we submit the HPB
> > > write
> > > request to the SCSI layer? if not, it will be a direct submission
> > > way.
> > > why not directly use direct way? or maybe you have a more advisable
> > > approach to work around this. would you please share with us.
> > > appreciate.
> > 
> > I am considering a direct submission way for the next version.
> > We will implement the write buffer command of HPB 2.0, after patching
> > HPB 1.0.
> > 
> > As for the direct submission of HPB releated command including HPB
> > write
> > buffer, I think we'd better discuss the right approach in depth
> > before
> > moving on to the next step.
> > 
> 
> Hi Daejun
> If you need reference code, you can freely copy my code from my RFC v3
> patchset. or if you need my side testing support, just let me, I can
> help you test your code.
> 
It will be good example code for developing HPB 2.0.

Thanks,
Daejun