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    SubjectRe: [Scst-devel] Fwd: Re: linuxcon 2010...
    On Mon, Aug 23, 2010 at 02:03:26PM -0400, Chetan Loke wrote:
    > I actually received 3+ off-post emails asking whether I was talking
    > about initiator or target in the 100K IOPS case below and what did I
    > mean by the ACKs.
    > I was referring to the 'Initiator' side.
    > ACKs == When scsi-ML down-calls the LLD via the queue-command, process
    > the sgl's(if you like) and then trigger the scsi_done up-call path.
    >

    Uhm, Intel and Microsoft demonstrated over 1 million IOPS
    using software iSCSI and a single 10 Gbit Ethernet NIC (Intel 82599).

    How come there is such a huge difference? What are we lacking in Linux?

    -- Pasi

    > Chetan Loke
    >
    > On Mon, Aug 23, 2010 at 12:07 PM, Chetan Loke <chetanloke@gmail.com> wrote:
    > > On Mon, Aug 23, 2010 at 11:11 AM, Bart Van Assche <bvanassche@acm.org> wrote:
    > >
    > >>
    > >> There is an important design difference between SCST and LIO: SCST by
    > >> defaults creates multiple threads to process the I/O operations for a
    > >> storage target, while LIO only creates a single thread per storage target.
    > >> This makes SCST perform measurably faster.
    > >>
    > >
    > > Forget that. You could have discussed this if there were code reviews
    > > or other mainline inclusion emails from James B. From what I have
    > > heard, the decision was taken around 8-9 months back.
    > > Would anyone like to either comment/validate/refute this please?  If
    > > not then I would kindly request these guys to stop taking us for a
    > > test drive. And also I'm not sure when was the last time James B.
    > > bench-marked our scsi-stack. Even if I ACK in the xmit-path then I
    > > can't push more than 100K IOPs. But other folks have re-engineered our
    > > linux-scsi stack and from what I've heard they can push > 300K+ IOPs.
    > > So I would just ignore performance discussion because I don't think
    > > folks have done even simple lame experiments in the last 1 year. Or
    > > may be I'm completely wrong and so please enlighten me so that I can
    > > re-run the tests.
    > >
    > >
    > >> Bart.
    > >>
    > > Chetan Loke
    > >
    >
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