I need to buy new RAM .
- First I need to know speed >> done
- Second I need to know latency >> how ?
All I tried from google.
dmidecode --type memory
dmidecode 2.11
dd if=/dev/zero of=/dev/sda2 bs=1G count=1 oflag=direct
apt-get install hardinfo
apt-get install sysinfo
cat /proc/meminfo
cat /var/log/dmesg | grep Memory
decode-dimms
update-pciids
lshw -C memory | grep clock
apt-get install lshw
lshw -C memory
3 Answers
What is Latency ?
A delay in transmitting data between a computer's RAM and its processor. Since RAM is not necessarily fast compared to the computer's processor, RAM latency can occur, causing a delay between the time a computer's hardware recognizes the need for a RAM access (initiates a request for data) and the time the data or instruction is available to the processor. If the CPU requests data that is not stored in the cache, then it will have to wait for the RAM to retrieve the data, opening the door to latency problems.
Where to check Latency of RAM ?
For Ubuntu install package i2c-tools and run
sudo modprobe eeprom
decode-dimms
Source : Ubuntu Forums & Major Source
I hope it will help you.
Please use command 1:
sudo dmidecode -t 17 or dmidecode -t memory
output for command 1:
# dmidecode 2.11
SMBIOS 2.6 present.
Handle 0x000E, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x000D
Error Information Handle: No Error
Total Width: 64 bits
Data Width: 64 bits
Size: 2048 MB
Form Factor: SODIMM
Set: 1
Locator: M1
Bank Locator: Bank 0
Type: DDR3
Type Detail: Synchronous
Speed: 1334 MHz
Manufacturer: 830B
Serial Number: DBC8287D
Asset Tag: 1012
Part Number: NT2GC64B8HC0NS-CG
Rank: Unknown
---------------------------------------
output command 2
# dmidecode 2.11
SMBIOS 2.6 present.
Handle 0x000D, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 16 GB
Error Information Handle: Not Provided
Number Of Devices: 4
Handle 0x000E, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x000D
Error Information Handle: No Error
Total Width: 64 bits
Data Width: 64 bits
Size: 2048 MB
Form Factor: SODIMM
Set: 1
Locator: M1
Bank Locator: Bank 0
Type: DDR3
Type Detail: Synchronous
Speed: 1334 MHz
Manufacturer: 830B
Serial Number: DBC8287D
Asset Tag: 1012
Part Number: NT2GC64B8HC0NS-CG
Rank: Unknown
Handle 0x000F, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x000D
Error Information Handle: No Error
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: SODIMM
Set: 1
Locator: M2
Bank Locator: Bank 1
Type: DDR3
Type Detail: Synchronous
Speed: 1334 MHz
Manufacturer: 0198
Serial Number: A30EEB39
Asset Tag: 1044
Part Number: 9905428-012.A00LF
Rank: Unknown
Handle 0x0010, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x000D
Error Information Handle: No Error
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: SODIMM
Set: 1
Locator: M3
Bank Locator: Bank 2
Type: DDR3
Type Detail: Synchronous
Speed: Unknown
Manufacturer:
Serial Number:
Asset Tag:
Part Number:
Rank: Unknown
Handle 0x0011, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x000D
Error Information Handle: No Error
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: SODIMM
Set: 1
Locator: M4
Bank Locator: Bank 3
Type: DDR3
Type Detail: Synchronous
Speed: Unknown
Manufacturer:
Serial Number:
Asset Tag:
Part Number:
Rank: Unknown
On my old Dell Vostro 3700 notebook, with Ubuntu 20.04, 'decode-dimms' worked for me (with 'modprobe eeprom'); it returned a bunch of info like:
Fundamental Memory type DDR3 SDRAM
Module Type SO-DIMM
...
Maximum module speed 1333 MHz (PC3-10600)
...
Minimum Cycle Time (tCK) 1.500 ns
Minimum CAS Latency Time (tAA) 13.125 ns
From Crucial site: "latency (ns) = clock cycle time (ns) x number of clock cycles"; so, to find CL class (number of clock cycles), divide "Minimum CAS Latency Time" (latency) by "Minimum Cycle Time" (clock cycle time): the nearest integer should be the CL value (I got 8.75, and CL9 should be consistent with my RAM modules).
Beware: 'decode-dimms' may not output infos on DDR4 systems without finding the correct module needed to read the new SPD Flash memory and it seems to work only on recent Linux releases as wrote Guilherme Parreira above; it may even show you infos about MAXIMUM performances of memory modules, not the actual values they are using. You are warned.
References:
Damieng blog - DDR4 memory information in Linux
