linux-kernel - Re: [RFC PATCH v3 0/5] scsi: ufs: Add Host Performance Booster Support

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Message-ID: <60647cf00d9db6818488a714b48b9b6e2a1eb728.camel@gmail.com>
Date:   Mon, 29 Jun 2020 13:25:03 +0200
From:   Bean Huo <huobean@...il.com>
To:     daejun7.park@...sung.com,
        "avri.altman@....com" <avri.altman@....com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "bvanassche@....org" <bvanassche@....org>,
        "tomas.winkler@...el.com" <tomas.winkler@...el.com>,
        ALIM AKHTAR <alim.akhtar@...sung.com>
Cc:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Sang-yoon Oh <sangyoon.oh@...sung.com>,
        Sung-Jun Park <sungjun07.park@...sung.com>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Jinyoung CHOI <j-young.choi@...sung.com>,
        Adel Choi <adel.choi@...sung.com>,
        BoRam Shin <boram.shin@...sung.com>
Subject: Re: [RFC PATCH v3 0/5] scsi: ufs: Add Host Performance Booster
 Support

Hi Daejun

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://lkml.org/lkml/2020/6/15/1492),
> 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.

> 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.


> There was Bart's comment that it was not good add an arbitrary
> timeout value
> to the request. (please refer to: 
> https://lkml.org/lkml/2020/6/11/1043)
> When no timer is added to the request, the SD timout will be set as
> default
> timeout at the block layer.
> 

I saw that, so I should add a timer in order to optimise HPB reqeust
scheduling/completition. this is ok so far.

> Thanks,
> Daejun

Thanks,
Bean