[389-users] Serious write-performance problems on RHEL6

Tue Apr 1 10:52:09 UTC 2014

Hi, Ludwig

Thanks for taking the time to reply.

I'm using this simple LDIF import file to generate the problem:
http://pastebin.com/NyNY650L
It generally hangs around the 7th record, and the complete import takes 2m32s!

Parent pid from /var/run/dirsrv/slapd-algieba.pid is 10382, and 'top -H' for it shows:

# top -H -p 10382

top - 11:45:02 up 5 days, 22:27,  9 users,  load average: 0.87, 0.35, 0.24
Tasks:  41 total,   1 running,  40 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.8%us,  0.2%sy,  0.0%ni, 97.6%id,  0.4%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   8060964k total,  7886612k used,   174352k free,   215412k buffers
Swap:  6291448k total,    11584k used,  6279864k free,  2588264k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
10892 dirsrv    20   0 11.9g 6.1g 1.9g R 99.7 79.1  46:19.78 ns-slapd
10881 dirsrv    20   0 11.9g 6.1g 1.9g S  2.0 79.1  40:58.88 ns-slapd
...

Standard top output:

top - 11:29:09 up 5 days, 22:11,  9 users,  load average: 0.35, 0.14, 0.16
Tasks: 219 total,   1 running, 218 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.8%us,  0.2%sy,  0.0%ni, 97.6%id,  0.4%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   8060964k total,  7887052k used,   173912k free,   215412k buffers
Swap:  6291448k total,    11584k used,  6279864k free,  2587968k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
10382 dirsrv    20   0 11.9g 6.1g 1.9g S 100.3 79.1  83:23.85 ns-slapd
25216 root      20   0 15168 1184  824 R  2.0  0.0   0:00.01 top

Output from pstack is here: http://pastebin.com/8LpfbdCb

I'm curious about the number of CoS lines, which I've highlighted.
I mention this as enabling Plugins in the error log shows an incredible amount of CoS activity - and the LDIF import above doesn't include any CoS attributes.
I'll disable the CoS rules and see whether this helps...

Thanks for the note about hardware. Sounds like it doesn't apply here; details are:
VM hardware: Dell PowerEdge R710 2x quad core Xeon.
Production hardware: Sun Fire V240 (Sparc, 8G RAM).

Best wishes,
Steve

-----Original Message-----
From: 389-users-bounces at lists.fedoraproject.org [mailto:389-users-bounces at lists.fedoraproject.org] On Behalf Of Ludwig Krispenz
Sent: 01 April 2014 08:33
To: 389-users at lists.fedoraproject.org
Subject: Re: [389-users] Serious write-performance problems on RHEL6

In the phase with high cpu usage, could you run
a) top -H -p <pid>
to see if there are many threads competing for the cpu or one or two 
occupying the cpu
b) pstack <pid>
to see what the threads are doing, sometimes pstack for the complete 
process doesn't look meaningful, you can also run pstack <tpid> where 
tpid is one of the threads consuming the cpu

You are on a VM with 2cpus, what is the real HW, there have been 
problems with RHDS on machines with Numa architecture if the threads of 
teh process have been distributed to different nodes. What was the HW 
for SunDS ?

Ludwig

On 03/31/2014 05:34 PM, Steve Holden wrote:
> Hi, folks
>
> I'm hoping to use 389 DS to replace our ancient Sun DS 5.2 service.
>
> I've hit a snag with my 389 development server; it's performance far worse
> than the 10 year-old servers it's intended to replace.
>
> Things looked promising: the old directory data has been imported (with
> only minor changes), read requests perform reasonably well, and isolated
> write requests are ok.
>
> However, even after a small number (typically 6) of consecutive write requests
> (basic attribute changes to a single entry, say) the ns-slapd process hits >100%
> CPU (of 2 CPUs) and stays there for *at least* 10 seconds per update, and blocks
> the client process attempting the update.
>
> I can't see anything obvious in the performance counters or the logs to suggest
> a problem. The updates are logged with "etime=0" in the access log.
>
> I've tried enabling different log levels in the error log.
> Is it normal for the Plugin level to show constant re-scanning of CoS templates?
>
> I'd be very grateful for any suggestions of how I can go about tracing where the
> Problem might be and how to resolve it...
>
> Best wishes,
> Steve
>
>
> Details
>
> The RHEL6.5 server is a VMware ESXi VM with 8GB RAM and 2x CPUs,
> and is running the latest EPEL package for RHEL6 (v1.2.11.15-32).
> (After a package upgrade a few weeks ago, I ran "setup-ds-admin.pl -u").
>
> The directory contains in excess of 200,000 entries, and
> its databases consume over 3.5GB on disk.
>
> The userRoot database has therefore been configured with a 4GB cache
> (and the general LDBM max cache is set at 6GB - though it's quite possible
> I haven't understood how to set these correctly - I've tried smaller numbers of each).
>
> The directory contains custom attributes, some of which are CoS,
> and many of which have been indexed (AFAIK, all attributes have been re-indexed).
>
> No replication has been configured so far.

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