Re: Same query taking less time in low configuration machine

Hi,

I am pasting the output of both server cpu speed and memory speed, and we
have same os (centos) on both the machines and i have downloaded the
postgres rpms from https://www.postgresql.org/

1) High end machine

[root(at)localhost ~]# dmidecode -t processor | grep Speed
Max Speed: 3600 MHz
Current Speed: 2666 MHz
Max Speed: 3600 MHz
Current Speed: 2666 MHz

Ram slots 16x4=64 GB

[root(at)localhost ~]# dmidecode --type 17
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 2.6 present.

Handle 0x1100, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x1000
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 64 bits
Size: 16384 MB
Form Factor: DIMM
Set: 1
Locator: DIMM_A1
Bank Locator: Not Specified
Type: DDR3
Type Detail: Synchronous Registered (Buffered)
Speed: 1333 MT/s
Manufacturer: 00CE00B380CE
Serial Number: 35E9FC94
Asset Tag: 02131263
Part Number: M393B2G70BH0-YH9
Rank: 2

cache size : 12288 KB

2) Low End machine

[root(at)localhost ~]# dmidecode -t processor | grep Speed
Max Speed: 3800 MHz
Current Speed: 3200 MHz

Ram slots 4x2=8GB
[root(at)localhost ~]# dmidecode --type 17
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.

Handle 0x0038, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x0037
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: DIMM1
Bank Locator: Not Specified
Type: DDR3
Type Detail: Synchronous
Speed: 1600 MHz
Manufacturer: Hynix/Hyundai
Serial Number: 0BB0390C003C
Asset Tag: 9876543210
Part Number: HMT351U6EFR8C-PB
Rank: 2
Configured Clock Speed: 1600 MHz

cache size : 6144 KB

Any other details required? kindly let me know how to obtain those, i
will share you the same.

Regards,
Vishwa S Kalyankar

On Tue, Jul 14, 2020 at 10:12 PM Kenneth Marshall <ktm(at)rice(dot)edu> wrote:

> On Tue, Jul 14, 2020 at 09:27:56PM +0530, Vishwa Kalyankar wrote:
> > HI,
> >
> > OS cache is updated and I had run the query few times with almost the
> same
> > result each time.
> >
> > Regards,
> > Vishwa
>
> Hi Vishwa,
>
> What are the CPU speeds, memory bandwidth, I/O bandwidth? Often the
> lower core count CPUs have a faster clock speed. What is the CPU cache
> size for both? Are you running the same OS and PostgreSQL build binaries
> on both?
>
> Regards,
> Ken
>