Re: arc_reclaim_thread running hot

2018-09-13 Thread Eric van Gyzen

On 9/13/18 8:18 AM, Eric van Gyzen wrote:
This morning, I found the arc_reclaim_thread running hot on my laptop 
running 12.0-ALPHA5 r338572.


vfs.zfs.arc_max="4294967296"  <-- 4 GiB

last pid: 13288;  load averages:  1.32,  1.26,  1.16
Mem: 456M Active, 3837M Inact, 743M Laundry, 2563M Wired, 167M Free
ARC: 1131M Total, 304M MFU, 145M MRU, 1344K Anon, 9116K Header, 671M Other
  89M Compressed, 361M Uncompressed, 4.03:1 Ratio

    22 root -8    -  0   256K CPU2 2 309:20  99.75% 
zfskern{arc_reclaim_thread}


zfs_arc_meta_strategy is still the default of 1.

I sampled the thread's stacks with

for N in `jot 1000`; do procstat -kk 100101; done | grep 100101

and put the results here:

https://people.freebsd.org/~vangyzen/arc_reclaim_thread_stacks.txt

I'm happy to help debug this.  Just let me know what you need.


The thread eventually returned to normal, and I've rebooted the system 
since then, so I no longer have any state.  The thread started running 
hot at 03:00, so maybe the daily periodic run triggered it.  I have to 
work now, but I'll try running the periodic stuff manually when I have time.


Eric
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Re: arc_reclaim_thread running hot

2018-09-13 Thread Daniel Nebdal
On Thu, 13 Sep 2018 at 15:19, Eric van Gyzen  wrote:
>
> This morning, I found the arc_reclaim_thread running hot on my laptop
> running 12.0-ALPHA5 r338572.
>
> vfs.zfs.arc_max="4294967296"  <-- 4 GiB
>
> last pid: 13288;  load averages:  1.32,  1.26,  1.16
>
> Mem: 456M Active, 3837M Inact, 743M Laundry, 2563M Wired, 167M Free
> ARC: 1131M Total, 304M MFU, 145M MRU, 1344K Anon, 9116K Header, 671M Other
>   89M Compressed, 361M Uncompressed, 4.03:1 Ratio
>
> 22 root -8-  0   256K CPU2 2 309:20  99.75%
> zfskern{arc_reclaim_thread}
>
> zfs_arc_meta_strategy is still the default of 1.
>
> I sampled the thread's stacks with
>
> for N in `jot 1000`; do procstat -kk 100101; done | grep 100101
>
> and put the results here:
>
> https://people.freebsd.org/~vangyzen/arc_reclaim_thread_stacks.txt
>
> I'm happy to help debug this.  Just let me know what you need.
>
> Eric

Just to summarize, these are the top 15 active
(guessing that the leftmost function is "current"):
 22 arc_space_return
 22 uma_dbg_free
 26 uma_dbg_alloc
 30 mi_switch
 31 uma_zalloc_arg
 33 multilist_sublist_lock
 34 __mtx_unlock_flags
 39 
 46 _sx_xlock
 48 hdr_full_cons
 50 uma_zfree_arg
 58 aggsum_add
 91 arc_adjust
156 _sx_xunlock
185 arc_evict_state

And the top 15 in total
(that is, no matter where in the call stack):
 44 multilist_sublist_lock
 44 uma_dbg_free
 46 _sx_xlock
 47 uma_dbg_alloc
 61 arc_space_return
127 aggsum_add
139 hdr_full_cons
156 _sx_xunlock
211 uma_zfree_arg
219 uma_zalloc_arg
833 arc_evict_state
926 arc_adjust
961 arc_reclaim_thread
961 fork_exit
961 fork_trampoline

(I have nothing sensible to add about the actual problem.)

-- 
Daniel Nebdal
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arc_reclaim_thread running hot

2018-09-13 Thread Eric van Gyzen
This morning, I found the arc_reclaim_thread running hot on my laptop 
running 12.0-ALPHA5 r338572.


vfs.zfs.arc_max="4294967296"  <-- 4 GiB

last pid: 13288;  load averages:  1.32,  1.26,  1.16 


Mem: 456M Active, 3837M Inact, 743M Laundry, 2563M Wired, 167M Free
ARC: 1131M Total, 304M MFU, 145M MRU, 1344K Anon, 9116K Header, 671M Other
 89M Compressed, 361M Uncompressed, 4.03:1 Ratio

   22 root -8-  0   256K CPU2 2 309:20  99.75% 
zfskern{arc_reclaim_thread}


zfs_arc_meta_strategy is still the default of 1.

I sampled the thread's stacks with

for N in `jot 1000`; do procstat -kk 100101; done | grep 100101

and put the results here:

https://people.freebsd.org/~vangyzen/arc_reclaim_thread_stacks.txt

I'm happy to help debug this.  Just let me know what you need.

Eric
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