Chris

Thank you very much for your advices.

First I tried changing "open files" limits (file locks is already
unlimited) but I didn't see a real improve. I tested also different
values of vfs_cache_pressure but also here I didn't see much difference.

When I started testing max_rpcs_in_flight (only the mdc parameters as
you advice) I got impressed: from 1700 to 4900 record/s.

2015/05/07 13:56:22 robinhood@daintrbh01[4199/1] STATS |    read speed
= 1707.75 record/sec
2015/05/07 13:57:22 robinhood@daintrbh01[4199/1] STATS |    read speed
= 3823.17 record/sec
2015/05/07 13:58:22 robinhood@daintrbh01[4199/1] STATS |    read speed
= 4903.52 record/sec
2015/05/07 13:59:22 robinhood@daintrbh01[4199/1] STATS |    read speed
= 3986.62 record/sec
2015/05/07 14:00:22 robinhood@daintrbh01[4199/1] STATS |    read speed
= 5474.05 record/sec
2015/05/07 14:01:22 robinhood@daintrbh01[4199/1] STATS |    read speed
= 4990.08 record/sec

Unfortunately this is not constant and after a while the speed went down
again. In this moment I'm seeing more or less values between 1454 to
3059.43 but in average is faster than before:

2015/05/07 17:14:01 robinhood@daintrbh01[21325/1] STATS |    read speed
= 2426.47 record/sec
2015/05/07 17:15:01 robinhood@daintrbh01[21325/1] STATS |    read speed
= 1454.42 record/sec
2015/05/07 17:16:01 robinhood@daintrbh01[21325/1] STATS |    read speed
= 2312.18 record/sec
2015/05/07 17:17:02 robinhood@daintrbh01[21325/1] STATS |    read speed
= 2692.42 record/sec
2015/05/07 17:18:02 robinhood@daintrbh01[21325/1] STATS |    read speed
= 1810.07 record/sec
2015/05/07 17:19:02 robinhood@daintrbh01[21325/1] STATS |    read speed
= 3059.43 record/sec

Also here I tested different values but I think 32 is the best for my
environment.

I set up also /proc/sys/lnet/debug to 0 following the advices I found in
this site
https://blogs.oracle.com/atulvid/entry/improving_performance_of_small_files

lru_size is 400 and lru_max_age 36000000 and for the moment I'm keeping
this two values.

Thank you again
Carmelo

On Wed, 2015-05-06 at 14:45 -0400, Chris Hunter wrote:
> If re-mounting lustre temporarily improves GET_INFO_FS, you may be 
> hitting client cache or parameter limit. A few suggestions to try on the 
> lustre client:
> - check ulimit settings before starting robinhood, especially number of 
> open files & file locks
> - set sysctl vfs_cache pressure for more aggressive reclaim of dentries 
> & inodes
> - on your lustre client, check mdc parameters: max_rpcs_in_flight, 
> lru_size & lru_max_age. FYI, its common to tune the lustre osc 
> parameters but rbh is more sensitive to mdc parameters
> 
> regards,
> chris hunter
> yale hpc group



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