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

From: Bean Huo <huobean@gmail.com>
To: 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>
Subject: Re: [RFC PATCH v3 0/5] scsi: ufs: Add Host Performance Booster Support
Date: Mon, 29 Jun 2020 13:25:03 +0200	[thread overview]
Message-ID: <60647cf00d9db6818488a714b48b9b6e2a1eb728.camel@gmail.com> (raw)
In-Reply-To: <336371513.41593411482259.JavaMail.epsvc@epcpadp2>

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