[ceph-users] OSD log being spammed with BlueStore stupidallocator dump

Wido den Hollander wido at 42on.com
Wed Oct 10 15:37:20 PDT 2018



On 10/11/2018 12:08 AM, Wido den Hollander wrote:
> Hi,
> 
> On a Luminous cluster running a mix of 12.2.4, 12.2.5 and 12.2.8 I'm
> seeing OSDs writing heavily to their logfiles spitting out these lines:
> 
> 
> 2018-10-10 21:52:04.019037 7f90c2f0f700  0 stupidalloc 0x0x55828ae047d0
> dump  0x15cd2078000~34000
> 2018-10-10 21:52:04.019038 7f90c2f0f700  0 stupidalloc 0x0x55828ae047d0
> dump  0x15cd22cc000~24000
> 2018-10-10 21:52:04.019038 7f90c2f0f700  0 stupidalloc 0x0x55828ae047d0
> dump  0x15cd2300000~20000
> 2018-10-10 21:52:04.019039 7f90c2f0f700  0 stupidalloc 0x0x55828ae047d0
> dump  0x15cd2324000~24000
> 2018-10-10 21:52:04.019040 7f90c2f0f700  0 stupidalloc 0x0x55828ae047d0
> dump  0x15cd26c0000~24000
> 2018-10-10 21:52:04.019041 7f90c2f0f700  0 stupidalloc 0x0x55828ae047d0
> dump  0x15cd2704000~30000
> 
> It goes so fast that the OS-disk in this case can't keep up and become
> 100% util.
> 
> This causes the OSD to slow down and cause slow requests and starts to flap.
> 
> It seems that this is *only* happening on OSDs which are the fullest
> (~85%) on this cluster and they have about ~400 PGs each (Yes, I know,
> that's high).
> 

After some searching I stumbled upon this Bugzilla report:
https://bugzilla.redhat.com/show_bug.cgi?id=1600138

That seems to be the same issue, although I'm not 100% sure.

Wido

> Looking at StupidAllocator.cc I see this piece of code:
> 
> void StupidAllocator::dump()
> {
>   std::lock_guard<std::mutex> l(lock);
>   for (unsigned bin = 0; bin < free.size(); ++bin) {
>     ldout(cct, 0) << __func__ << " free bin " << bin << ": "
>                   << free[bin].num_intervals() << " extents" << dendl;
>     for (auto p = free[bin].begin();
>          p != free[bin].end();
>          ++p) {
>       ldout(cct, 0) << __func__ << "  0x" << std::hex << p.get_start()
> << "~"
>                     << p.get_len() << std::dec << dendl;
>     }
>   }
> }
> 
> I'm just wondering why it would spit out these lines and what's causing it.
> 
> Has anybody seen this before?
> 
> Wido
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