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    SubjectRe: What's in linux-2.6-block.git
    >>>>> "Al" == Al Boldi <a1426z@gawab.com> writes:

    Al> Jens Axboe wrote:
    >> On Wed, Sep 13 2006, Al Boldi wrote:
    >> > Jens Axboe wrote:
    >> > > This lists the main features of the 'block' branch, which is bound for
    >> > > Linus when 2.6.19 opens:
    >> > >
    >> > > - Splitting of request->flags into two parts:
    >> > > - cmd type
    >> > > - modified flags
    >> > > Right now it's a bit of a mess, splitting this up invites a cleaner
    >> > > usage and also enables us to implement generic "messages" passed on
    >> > > the regular queue for the device.
    >> > >
    >> > > - Abstract out the request back merging and put it into the core io
    >> > > scheduler layer. Cleans up all the io schedulers, and noop gets
    >> > > merging for "free".
    >> > >
    >> > > - Abstract out the rbtree sorting. Gets rid of duplicated code in
    >> > > as/cfq/deadline.
    >> > >
    >> > > - General shrinkage of the request structure.
    >> > >
    >> > > - Killing dynamic rq private structures in deadline/as/cfq. This
    >> > > should speed up the io path somewhat, as we avoid allocating several
    >> > > structures (struct request + scheduler private request) for each io
    >> > > request.
    >> > >
    >> > > - meta data io logging for blktrace.
    >> > >
    >> > > - CFQ improvements.
    >> > >
    >> > > - Make the block layer configurable through Kconfig (David Howells).
    >> > >
    >> > > - Lots of cleanups.
    >> >
    >> > Does it also address the strange "max_sectors_kb<>192 causes a
    >> > 50%-slowdown" problem?
    >>
    >> (remember to cc me/others when replying, I can easily miss lkml
    >> messages for several days otherwise).
    >>
    >> It does not, the investigation of that is still pending I'm afraid. The
    >> data is really puzzling, I'm inclined to think it's drive related. Are
    >> you reproducing it just one box/drive, or on several?

    Al> Several boxes, same drive.

    Al> /dev/hda:

    Al> ATA device, with non-removable media
    Al> Model Number: WDC WD1200JB-00DUA0
    Al> Serial Number: WD-WMACM1007651
    Al> Firmware Revision: 65.13G65
    Al> Standards:
    Al> Supported: 6 5 4 3
    Al> Likely used: 6

    I've got a pair of drives which are very close in model type, and I
    can run some non-destructive tests on them if you like to confirm
    what's going on here if you like:

    /dev/hde:

    ATA device, with non-removable media
    Model Number: WDC WD1200JB-00CRA1
    Serial Number: WD-WMA8C4365875
    Firmware Revision: 17.07W17
    Standards:
    Supported: 5 4 3
    Likely used: 6
    jfsnew:~> sudo hdparm -I /dev/hdg | head

    /dev/hdg:

    ATA device, with non-removable media
    Model Number: WDC WD1200JB-00EVA0
    Serial Number: WD-WMAEK2844058
    Firmware Revision: 15.05R15
    Standards:
    Supported: 6 5 4
    Likely used: 6


    The drives have different defaul max_sectors too:

    > cat /sys/block/hdg/queue/max_sectors_kb
    512
    > cat /sys/block/hde/queue/max_sectors_kb
    128

    Let me know your test method and I'll run it here and post the
    results.

    John
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