Re: Where is my bottleneck?

From: Arnau <arnaulist(at)andromeiberica(dot)com>
To:
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: Where is my bottleneck?
Date: 2006-01-24 19:53:50
Message-ID: 43D685CE.1030206@andromeiberica.com
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Scott Marlowe wrote:

> Well, this might get more traction on the perform list, just fyi. Admin
> is more generally for questions about adding users, setting permissions
> and such.

I know and I apologize for the cross-posting, I also sent the same
message to the performance list.

>
> That said, it looks like you're likely I/O bound.
>
> Do you have Hyperthreading turned on?

yes I have, when I do cat /proc/cpuinfo I get 4 CPUs

>
> What do iostat and vmstat have to say?

here I post the result of iostat 10 -x

asme(at)SD22-SINER5:/$ iostat 10 -x
Linux 2.4.26-1-686-smp (SD22-SINER5) 01/24/06

avg-cpu: %user %nice %sys %iowait %idle
16.03 0.00 94.98 0.00 144.54

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s
avgrq-sz avgqu-sz await svctm %util
scsi/host0/bus1/target0/lun0/disc
89.37 14.15 48.15 95.82 1.30 25.54 0.65 12.77
0.79 0.00 0.05 0.00 0.00
scsi/host0/bus1/target0/lun0/part1
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.26 0.00 48.69 48.63 0.00
scsi/host0/bus1/target0/lun0/part2
0.01 0.25 0.02 0.22 0.22 3.77 0.11 1.89
17.12 0.00 6.29 1.80 0.04
scsi/host0/bus1/target0/lun0/part5
0.02 0.02 0.01 0.00 0.21 0.20 0.10 0.10
33.85 0.00 58.89 38.02 0.05
scsi/host0/bus1/target0/lun0/part6
0.05 0.35 0.10 0.47 1.18 6.55 0.59 3.27
13.58 0.00 2.70 1.64 0.09
scsi/host0/bus1/target0/lun0/part7
0.06 0.60 0.01 0.03 0.53 5.10 0.27 2.55
137.26 0.00 38.02 22.68 0.09
scsi/host0/bus1/target0/lun0/part8
0.14 0.57 0.01 0.03 1.18 4.79 0.59 2.40
155.70 0.00 12.07 14.63 0.06
scsi/host0/bus1/target0/lun0/part9
89.09 12.35 48.00 95.07 107.78 5.13 53.89 2.56
0.09 0.00 0.04 0.02 0.05

avg-cpu: %user %nice %sys %iowait %idle
27.35 0.00 16.25 0.00 56.40

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s
avgrq-sz avgqu-sz await svctm %util
scsi/host0/bus1/target0/lun0/disc
420.60 2070.00 87.30 152.10 4060.00 17830.40 2030.00
8915.20 91.44 14.06 57.70 4.16 99.60
scsi/host0/bus1/target0/lun0/part1
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part2
0.00 0.70 0.00 1.40 0.00 16.80 0.00 8.40
12.00 0.07 52.14 5.00 0.70
scsi/host0/bus1/target0/lun0/part5
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part6
0.00 0.40 0.00 0.40 0.00 6.40 0.00 3.20
16.00 0.02 40.00 40.00 1.60
scsi/host0/bus1/target0/lun0/part7
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part8
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part9
420.60 2068.90 87.30 150.30 4060.00 17807.20 2030.00
8903.60 92.03 13.97 57.77 4.19 99.60

avg-cpu: %user %nice %sys %iowait %idle
31.38 0.00 15.55 0.00 53.08

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s
avgrq-sz avgqu-sz await svctm %util
scsi/host0/bus1/target0/lun0/disc
388.80 2266.70 219.20 182.00 4876.80 19571.20 2438.40
9785.60 60.94 21.54 1059879.18 2.49 99.80
scsi/host0/bus1/target0/lun0/part1
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part2
0.00 0.30 0.00 0.40 0.00 5.60 0.00 2.80
14.00 0.01 17.50 17.50 0.70
scsi/host0/bus1/target0/lun0/part5
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part6
0.00 0.20 0.00 0.40 0.00 4.80 0.00 2.40
12.00 0.01 22.50 22.50 0.90
scsi/host0/bus1/target0/lun0/part7
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part8
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00
scsi/host0/bus1/target0/lun0/part9
388.80 2266.20 219.20 181.20 4876.80 19560.80 2438.40
9780.40 61.03 21.52 54.32 2.49 99.80

> Does your RAID 5 have the option for batter backed cache?

I don't know how to do that, I didn't configure this machine.

> Is your load mostly read, or a mix or read and write?

On this machine there are about 200 DDBB running on it, the activity
on them is a mix of read/write operations some depending on the tables
of each DB. The size of the DB varies a lot, every day we do a pg_dump
with a compressed format. The biggest one takes 746M, 5 are between 46M
and 13M. 40 between 10M - 1M and the rest their dump takes less than 1M.

Cheers!
--
Arnau

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