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


    >
    > Hi Avri
    >
    > On Mon, 2020-06-29 at 05:24 +0000, Avri Altman wrote:
    > > Hi Bean,
    > > >
    > > > Hi Daejun
    > > >
    > > > Seems you intentionally ignored to give you comments on my
    > > > suggestion.
    > > > let me provide the reason.
    > > >
    > > > Before submitting your next version patch, please check your L2P
    > > > mapping HPB reqeust submission logical algorithem. I have did
    > > > 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
    > > > your current work queue scheduling, since you didn't add the timer
    > > > for
    > > > each HPB request.
    > >
    > > In device control mode, the various decisions,
    > > and specifically those that are causing repetitive evictions,
    > > are made by the device.
    > > Is this the issue that you are referring to?
    > >
    >
    > For this device mode, if HPB mapping table of the active region becomes
    > dirty in the UFS device side, there is repetitive inactive rsp, but it
    > is not the reason for the condition I mentioned here.
    >
    > > As for the driver, do you see any issue that is causing unnecessary
    > > latency?
    > >
    >
    > In Daejun's patch, it now uses work_queue, and as long there is new RSP of
    > thesubregion to be activated, the driver will queue "work" to this work
    > queue, actually, this is deferred work. we don't know when it will be
    > scheduled/finished. we need to optimize it.
    But those "to-do" lists are checked on every completion interrupt and on every resume.
    Do you see any scenario in which the "to-be-activated" or "to-be-inactivate" work is getting starved?

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