2009/5/29 Scott Carey <sc...@richrelevance.com>

>
> On 5/28/09 6:54 PM, "Greg Smith" <gsm...@gregsmith.com> wrote:
>
> > 2) You have very new hardware and a very old kernel.  Once you've done
> the
> > above, if you're still not happy with performance, at that point you
> > should consider using a newer one.  It's fairly simple to build a Linux
> > kernel using the same basic kernel parameters as the stock RedHat one.
> > 2.6.28 is six months old now, is up to 2.6.28.10, and has gotten a lot
> > more testing than most kernels due to it being the Ubuntu 9.04 default.
> > I'd suggest you try out that version.
>
>
> Comparing RedHat's 2.6.18, heavily patched, fix backported kernel to the
> original 2.6.18 is really hard.  Yes, much of it is old, but a lot of stuff
> has been backported.
> I have no idea if things related to this case have been backported.
>  Virtual
> memory management is complex and only bug fixes would likely go in however.
> But RedHat 5.3 for example put all the new features for Intel's latest
> processor in the release (which may not even be in 2.6.28!).
>
> There are operations/IT people won't touch Ubuntu etc with a ten foot pole
> yet for production.  That may be irrational, but such paranoia exists.  The
> latest postgres release is generally a hell of a lot safer than the latest
> linux kernel, and people get paranoid about their DB.
>
> If you told someone who has to wake up at 3AM by page if the system has an
> error that "oh, we patched our own kenrel build into the RedHat OS" they
> might not be ok with that.
>
> Its a good test to see if this problem is fixed in the kernel. I've seen
> CentOS 5.2 go completely nuts with system CPU time and context switches
> with
> kswapd many times before.  I haven't put the system under the same stress
> with 5.3 yet however.
>

One of the server is: Intel Xeon X7350 2.93GHz, RH 5.3 and kernel
2.6.18-128.el5.
and the perfonmace is bad too, so i don't  think the probles is the kernel

The two servers that I tested (HP-785 Opteron and IBM x3950 M2 Xeon) have
NUMA architecture. and I thought the problem was caused by NUMA.

http://archives.postgresql.org/pgsql-admin/2008-11/msg00157.php

I'm trying another server, an HP blade bl 680 with Xeon E7450 (4 CPU x 6
cores= 24 cores) without NUMA architecture, but the CPUs are also going up.

procs -----------memory---------- ---swap-- -----io---- --system--
-----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id
wa st
 1  0      0 46949972 116908 17032964    0    0    15    31    2    2  1  0
98  0  0
 2  0      0 46945880 116916 17033068    0    0    72   140 2059 3140  1  1
97  0  0
329  0      0 46953260 116932 17033208    0    0    24   612 1435 194237 44
3 53  0  0
546  0      0 46952912 116940 17033208    0    0     4   136 1090 327047 96
4  0  0  0
562  0      0 46951052 116940 17033224    0    0     0     0 1095 323034 95
4  0  0  0
514  0      0 46949200 116952 17033212    0    0     0   224 1088 330178 96
3  1  0  0
234  0      0 46948456 116952 17033212    0    0     0     0 1106 315359 91
5  4  0  0
 4  0      0 46958376 116968 17033272    0    0    16   396 1379 223499 47
3 49  0  0
 1  1      0 46941644 116976 17033224    0    0   152  1140 2662 5540  4  2
93  1  0
 1  0      0 46943196 116984 17033248    0    0   104   604 2307 3992  4  2
94  0  0
 1  1      0 46931544 116996 17033568    0    0   104  4304 2318 3585  1  1
97  1  0
 0  0      0 46943572 117004 17033568    0    0    32   204 2007 2986  1  1
98  0  0


 Now i don't  think the probles is NUMA.


The developer team will fix de aplication  and then i will test again.

I believe that when the application closes the connection the problem could
be solved, and then 16 cores in a server does the work instead of a 32 or
24.


Regards...

--Fabrix

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