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    SubjectRe: xfs: does mkfs.xfs require fancy switches to get decent performance? (was Tux3 Report: How fast can we fsync?)
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    Daniel Phillips wrote:
    > On 05/12/2015 02:03 AM, Pavel Machek wrote:
    >> I'd call system with 65 tasks doing heavy fsync load at the some time
    >> "embarrassingly misconfigured" :-). It is nice if your filesystem can
    >> stay fast in that case, but...
    >
    > Well, Tux3 wins the fsync race now whether it is 1 task, 64 tasks or
    > 10,000 tasks. At the high end, maybe it is just a curiosity, or maybe
    > it tells us something about how Tux3 is will scale on the big machines
    > that XFS currently lays claim to. And Java programmers are busy doing
    > all kinds of wild and crazy things with lots of tasks. Java almost
    > makes them do it. If they need their data durable then they can easily
    > create loads like my test case.
    >
    > Suppose you have a web server meant to serve 10,000 transactions
    > simultaneously and it needs to survive crashes without losing client
    > state. How will you do it? You could install an expensive, finicky
    > database, or you could write some Java code that happens to work well
    > because Linux has a scheduler and a filesystem that can handle it.
    > Oh wait, we don't have the second one yet, but maybe we soon will.
    >
    > I will not claim that stupidly fast and scalable fsync is the main
    > reason that somebody should want Tux3, however, the lack of a high
    > performance fsync was in fact used as a means of spreading FUD about
    > Tux3, so I had some fun going way beyond the call of duty to answer
    > that. By the way, I am still waiting for the original source of the
    > FUD to concede the point politely, but maybe he is waiting for the
    > code to land, which it still has not as of today, so I guess that is
    > fair. Note that it would have landed quite some time ago if Tux3 was
    > already merged.

    Well, stupidly fast and scalable fsync sounds wonderful to me; it's the
    primary pain point in LMDB write performance now.

    http://symas.com/mdb/ondisk/

    I look forward to testing Tux3 when usable code shows up in a public repo.

    --
    -- Howard Chu
    CTO, Symas Corp. http://www.symas.com
    Director, Highland Sun http://highlandsun.com/hyc/
    Chief Architect, OpenLDAP http://www.openldap.org/project/


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