Can you provide the output of
Q MULTITHREAD and Q SRM
Regards, Phil Tully
Chief Architect-z/VM & z/Linux
phil.tu...@adp.com
cell: 973-202-7427
1-800 377-0237,,5252697#
On 11/3/20, 8:47 AM, "Linux on 390 Port on behalf of Grzegorz Powiedziuk"
<LINUX-390@VM.MARIST.EDU on behalf of gpowiedz...@gmail.com> wrote:
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Hi, I could use some ideas. We moved a huge db2 from old p7 aix to rhel7 on
Z and we are having big performance issues.
Same memory, CPU number is down from 12 to 10. Although they had
multithreading ON so they saw more "cpus" We have faster disks (moved to
flash), faster FCP cards and faster network adapters.
We are running on z114 and at this point that is practically the only VM
running with IFLs on this box.
It seems that when "jobs" run on their own, they finish faster than what
they were getting on AIX.
But problems start if there is more than we can chew. So either few jobs
running at the same time or some reorgs running in the database.
Load average goes to 150-200, cpus are at 100% (kernel time can go to
20-30% ) but no iowaits.
Plenty of memory available.
At this point everything becomes extremely slow, people are starting having
problems with connecting to db2 (annd sshing), basically it becomes a
nightmare
This db2 is massive (30+TB) and it is a multinode configuration (17 nodes
running on the same host). We moved it like this 1:1 from that old AIX.
DB2 is running on the ext4 filesystem (Actually a huge number of
filesystems- each NODE is a separate logical volume). Separate for logs,
data.
If this continues like this, we will add 2 cpus but I have a feeling that
it will not make much difference.
I know that we end up with a massive number of processes and a massive
number of file descriptors (lsof sice it shows also threads now, is
practically useless - it would run for way too long - 10-30 minutes
probably) .
A snapshot from just now:
top - 08:37:50 up 11 days, 12:04, 28 users, load average: 188.29, 151.07,
133.54
Tasks: 1843 total, 11 running, 1832 sleeping, 0 stopped, 0 zombie
%Cpu0 : 76.3 us, 16.6 sy, 0.0 ni, 0.0 id, 0.0 wa, 1.0 hi, 3.2 si,
2.9 st
%Cpu1 : 66.1 us, 31.3 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.6 hi, 1.3 si,
0.6 st
%Cpu2 : 66.9 us, 31.2 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.3 hi, 1.3 si,
0.3 st
%Cpu3 : 74.7 us, 23.4 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.3 hi, 1.3 si,
0.3 st
%Cpu4 : 86.7 us, 10.7 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.6 hi, 1.3 si,
0.6 st
%Cpu5 : 83.8 us, 13.6 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.6 hi, 1.6 si,
0.3 st
%Cpu6 : 81.6 us, 15.2 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.6 hi, 1.9 si,
0.6 st
%Cpu7 : 70.6 us, 26.2 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.6 hi, 1.9 si,
0.6 st
%Cpu8 : 70.5 us, 26.6 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.6 hi, 1.6 si,
0.6 st
%Cpu9 : 84.1 us, 13.6 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.3 hi, 1.3 si,
0.6 st
KiB Mem : 15424256+total, 1069280 free, 18452168 used, 13472112+buff/cache
KiB Swap: 52305904 total, 51231216 free, 1074688 used. 17399028 avail Mem
Where can I look for potential relief? Everyone was hoping for a better
performance not worse.I am hoping that there is something we can tweak to
make this better.
I will appreciate any ideas!
thanks
Gregory
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