Re: osd_snap_trim_sleep keeps locks PG during sleep?

Peter Maloney <peter.maloney@xxxxxxxxxxxxxxxxxxxx> · Sun, 5 Feb 2017 23:27:04 +0100



    On 02/03/17 19:54, David Turner wrote:

    
      Our current solution in Hammer
        involves a daemon monitoring the cluster load and setting the
        osd_snap_trim_sleep accordingly between 0 and 0.35 which does a
        good job of preventing IO blocking and help us to clear out the
        snap_trim_q each day.  These settings not being injectable in
        Jewel would negate an option of using variable settings
        throughout the day.
    
    Are you sure they're not injectable? [Almost?] everything says
    "unchangable", but it takes effect anyway. I have tested
    "snap_trim_sleep", and as Nick has pointed out, it seems to cause
    rather than prevent blocks (and I found the sweet spot is 0, but he
    seems to think it's higher). I can reproduce that very reliably
    using injectargs (+5 to sleep means +5s block length), so (unless
    luck can happen in such extreme ways, or somehow only part of the
    effect changed) they are changable.

    
    I'm using Jewel. So I am now using:

    
    osd_pg_max_concurrent_snap_trims=1

    osd_snap_trim_sleep=0

    
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