Category Archives: Learning

Critical Path != Critical Section

Posted on by
Reply

I always get the concepts “critical path” and “critical section” confused.

The “critical section” is the part in your algorithm which you must hold a lock for; whereas the “critical path” is an idea from hardware design which relates to the time taken for the longest combinatorial logic that needs to be processed during a clock cycle, thus limiting the frequency you can run your clock at.

Although the terminology “critical path” came from hardware, the same terminology is used in software. ChatGPT has a fairly good write-up on the two uses of the term “critical path”.

I learned a little more about this in Introduction to VHDL for FPGA and ASIC design.

CRC

Posted on by
Reply

I watched Ben Eater’s videos How do CRCs work? and Checksums and Hamming distance (the full course is Learn about error detection) then found the Wikipedia page: Cyclic redundancy check.

Also of interest:

Samsung 990 PRO firmware version

Posted on by
Reply

I’m having an issue with my Samsung 990 PRO drive. Gonna try upgrading the firmware. Actually got myself a new computer just for the purpose. Figured I should start with knowing what the firmware version is presently. ChatGPT strikes again. Firmware version is 1B2QJXD7.

-------------------
Wed May 31 11:14:03 [bash:5.2.15 jobs:0 error:0 time:0]
jj5@charm:/home/jj5
$ ll /dev/disk/by-id/
total 0
drwxr-xr-x 2 root root 1.3K May 31 03:04 .
drwxr-xr-x 9 root root  180 May 30 08:45 ..
lrwxrwxrwx 1 root root    9 May 30 08:45 ata-DRW-24D5MT_KLCL6MF4200 -> ../../sr0
lrwxrwxrwx 1 root root    9 May 31 03:04 ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0D5506W -> ../../sdb
lrwxrwxrwx 1 root root   10 May 31 03:04 ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0D5506W-part1 -> ../../sdb1
lrwxrwxrwx 1 root root   10 May 31 03:04 ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0D5506W-part9 -> ../../sdb9
lrwxrwxrwx 1 root root    9 May 31 03:04 ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0D8E3C9 -> ../../sda
lrwxrwxrwx 1 root root   10 May 31 03:04 ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0D8E3C9-part1 -> ../../sda1
lrwxrwxrwx 1 root root   10 May 31 03:04 ata-WDC_WD30EFRX-68EUZN0_WD-WMC4N0D8E3C9-part9 -> ../../sda9
lrwxrwxrwx 1 root root    9 May 30 08:45 md-name-charm:0 -> ../../md0
lrwxrwxrwx 1 root root    9 May 30 08:45 md-name-charm:1 -> ../../md1
lrwxrwxrwx 1 root root    9 May 30 08:45 md-uuid-9ef6fffa:0d37be5a:7842f20e:1319d620 -> ../../md1
lrwxrwxrwx 1 root root    9 May 30 08:45 md-uuid-f52df5c3:9aa1e0f1:8eab0df8:9808eaeb -> ../../md0
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-eui.00000000000000000026b768642eff55 -> ../../nvme1n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.00000000000000000026b768642eff55-part1 -> ../../nvme1n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.00000000000000000026b768642eff55-part9 -> ../../nvme1n1p9
lrwxrwxrwx 1 root root   13 May 30 09:57 nvme-eui.00000000000000000026b768642eff65 -> ../../nvme3n1
lrwxrwxrwx 1 root root   15 May 30 09:57 nvme-eui.00000000000000000026b768642eff65-part1 -> ../../nvme3n1p1
lrwxrwxrwx 1 root root   15 May 30 09:57 nvme-eui.00000000000000000026b768642eff65-part9 -> ../../nvme3n1p9
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-eui.00253842314123dd -> ../../nvme4n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.00253842314123dd-part1 -> ../../nvme4n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.00253842314123dd-part9 -> ../../nvme4n1p9
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-eui.6479a74fb0c004b7 -> ../../nvme2n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c004b7-part1 -> ../../nvme2n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c004b7-part2 -> ../../nvme2n1p2
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c004b7-part3 -> ../../nvme2n1p3
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c004b7-part4 -> ../../nvme2n1p4
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c004b7-part5 -> ../../nvme2n1p5
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-eui.6479a74fb0c00509 -> ../../nvme0n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c00509-part1 -> ../../nvme0n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c00509-part2 -> ../../nvme0n1p2
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c00509-part3 -> ../../nvme0n1p3
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c00509-part4 -> ../../nvme0n1p4
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-eui.6479a74fb0c00509-part5 -> ../../nvme0n1p5
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-KINGSTON_SNV2S2000G_50026B768642EFF5 -> ../../nvme1n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-KINGSTON_SNV2S2000G_50026B768642EFF5-part1 -> ../../nvme1n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-KINGSTON_SNV2S2000G_50026B768642EFF5-part9 -> ../../nvme1n1p9
lrwxrwxrwx 1 root root   13 May 30 09:57 nvme-KINGSTON_SNV2S2000G_50026B768642EFF6 -> ../../nvme3n1
lrwxrwxrwx 1 root root   15 May 30 09:57 nvme-KINGSTON_SNV2S2000G_50026B768642EFF6-part1 -> ../../nvme3n1p1
lrwxrwxrwx 1 root root   15 May 30 09:57 nvme-KINGSTON_SNV2S2000G_50026B768642EFF6-part9 -> ../../nvme3n1p9
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100092 -> ../../nvme2n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100092-part1 -> ../../nvme2n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100092-part2 -> ../../nvme2n1p2
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100092-part3 -> ../../nvme2n1p3
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100092-part4 -> ../../nvme2n1p4
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100092-part5 -> ../../nvme2n1p5
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100095 -> ../../nvme0n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100095-part1 -> ../../nvme0n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100095-part2 -> ../../nvme0n1p2
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100095-part3 -> ../../nvme0n1p3
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100095-part4 -> ../../nvme0n1p4
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-PNY_CS3140_1TB_SSD_PNY21242106180100095-part5 -> ../../nvme0n1p5
lrwxrwxrwx 1 root root   13 May 30 08:45 nvme-Samsung_SSD_990_PRO_2TB_S6Z2NJ0W215164J -> ../../nvme4n1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-Samsung_SSD_990_PRO_2TB_S6Z2NJ0W215164J-part1 -> ../../nvme4n1p1
lrwxrwxrwx 1 root root   15 May 30 08:45 nvme-Samsung_SSD_990_PRO_2TB_S6Z2NJ0W215164J-part9 -> ../../nvme4n1p9
lrwxrwxrwx 1 root root    9 May 30 08:45 wwn-0x5001480000000000 -> ../../sr0
lrwxrwxrwx 1 root root    9 May 31 03:04 wwn-0x50014ee604f5f467 -> ../../sda
lrwxrwxrwx 1 root root   10 May 31 03:04 wwn-0x50014ee604f5f467-part1 -> ../../sda1
lrwxrwxrwx 1 root root   10 May 31 03:04 wwn-0x50014ee604f5f467-part9 -> ../../sda9
lrwxrwxrwx 1 root root    9 May 31 03:04 wwn-0x50014ee65a4af2ed -> ../../sdb
lrwxrwxrwx 1 root root   10 May 31 03:04 wwn-0x50014ee65a4af2ed-part1 -> ../../sdb1
lrwxrwxrwx 1 root root   10 May 31 03:04 wwn-0x50014ee65a4af2ed-part9 -> ../../sdb9
-------------------
Wed May 31 11:14:11 [bash:5.2.15 jobs:0 error:0 time:8]
jj5@charm:/home/jj5
$ sudo nvme smart-log /dev/nvme4
Smart Log for NVME device:nvme4 namespace-id:ffffffff
critical_warning                        : 0
temperature                             : 45°C (318 Kelvin)
available_spare                         : 100%
available_spare_threshold               : 10%
percentage_used                         : 0%
endurance group critical warning summary: 0
Data Units Read                         : 2,237,856 (1.15 TB)
Data Units Written                      : 10,957,014 (5.61 TB)
host_read_commands                      : 48,079,050
host_write_commands                     : 119,766,894
controller_busy_time                    : 282
power_cycles                            : 31
power_on_hours                          : 23
unsafe_shutdowns                        : 16
media_errors                            : 0
num_err_log_entries                     : 0
Warning Temperature Time                : 0
Critical Composite Temperature Time     : 0
Temperature Sensor 1           : 45°C (318 Kelvin)
Temperature Sensor 2           : 49°C (322 Kelvin)
Thermal Management T1 Trans Count       : 0
Thermal Management T2 Trans Count       : 0
Thermal Management T1 Total Time        : 0
Thermal Management T2 Total Time        : 0
-------------------
Wed May 31 11:36:59 [bash:5.2.15 jobs:0 error:0 time:0]
root@charm:/home/jj5
# nvme id-ctrl /dev/nvme4 -H
NVME Identify Controller:
vid       : 0x144d
ssvid     : 0x144d
sn        : S6Z2NJ0W215164J     
mn        : Samsung SSD 990 PRO 2TB                 
fr        : 1B2QJXD7
rab       : 2
ieee      : 002538
cmic      : 0
  [3:3] : 0     ANA not supported
  [2:2] : 0     PCI
  [1:1] : 0     Single Controller
  [0:0] : 0     Single Port

mdts      : 9
cntlid    : 0x1
ver       : 0x20000
rtd3r     : 0x30d40
rtd3e     : 0x989680
oaes      : 0x200
  [31:31] : 0   Discovery Log Change Notice Not Supported
  [27:27] : 0   Zone Descriptor Changed Notices Not Supported
  [15:15] : 0   Normal NSS Shutdown Event Not Supported
  [14:14] : 0   Endurance Group Event Aggregate Log Page Change Notice Not Supported
  [13:13] : 0   LBA Status Information Notices Not Supported
  [12:12] : 0   Predictable Latency Event Aggregate Log Change Notices Not Supported
  [11:11] : 0   Asymmetric Namespace Access Change Notices Not Supported
  [9:9] : 0x1   Firmware Activation Notices Supported
  [8:8] : 0     Namespace Attribute Changed Event Not Supported

ctratt    : 0x10
  [19:19] : 0   Flexible Data Placement Not Supported
  [15:15] : 0   Extended LBA Formats Not Supported
  [14:14] : 0   Delete NVM Set Not Supported
  [13:13] : 0   Delete Endurance Group Not Supported
  [12:12] : 0   Variable Capacity Management Not Supported
  [11:11] : 0   Fixed Capacity Management Not Supported
  [10:10] : 0   Multi Domain Subsystem Not Supported
  [9:9] : 0     UUID List Not Supported
  [8:8] : 0     SQ Associations Not Supported
  [7:7] : 0     Namespace Granularity Not Supported
  [6:6] : 0     Traffic Based Keep Alive Not Supported
  [5:5] : 0     Predictable Latency Mode Not Supported
  [4:4] : 0x1   Endurance Groups Supported
  [3:3] : 0     Read Recovery Levels Not Supported
  [2:2] : 0     NVM Sets Not Supported
  [1:1] : 0     Non-Operational Power State Permissive Not Supported
  [0:0] : 0     128-bit Host Identifier Not Supported

rrls      : 0
cntrltype : 1
  [7:2] : 0     Reserved
  [1:0] : 0x1   I/O Controller
fguid     : 00000000-0000-0000-0000-000000000000
crdt1     : 0
crdt2     : 0
crdt3     : 0
nvmsr     : 0
  [1:1] : 0     NVM subsystem Not part of an Enclosure
  [0:0] : 0     NVM subsystem Not part of an Storage Device

vwci      : 0
  [7:7] : 0     VPD Write Cycles Remaining field is Not valid.
  [6:0] : 0     VPD Write Cycles Remaining 

mec       : 0
  [1:1] : 0     NVM subsystem Not contains a Management Endpoint on a PCIe port
  [0:0] : 0     NVM subsystem Not contains a Management Endpoint on an SMBus/I2C port

oacs      : 0x17
  [10:10] : 0   Lockdown Command and Feature Not Supported
  [9:9] : 0     Get LBA Status Capability Not Supported
  [8:8] : 0     Doorbell Buffer Config Not Supported
  [7:7] : 0     Virtualization Management Not Supported
  [6:6] : 0     NVMe-MI Send and Receive Not Supported
  [5:5] : 0     Directives Not Supported
  [4:4] : 0x1   Device Self-test Supported
  [3:3] : 0     NS Management and Attachment Not Supported
  [2:2] : 0x1   FW Commit and Download Supported
  [1:1] : 0x1   Format NVM Supported
  [0:0] : 0x1   Security Send and Receive Supported

acl       : 7
aerl      : 3
frmw      : 0x16
  [5:5] : 0     Multiple FW or Boot Update Detection Not Supported
  [4:4] : 0x1   Firmware Activate Without Reset Supported
  [3:1] : 0x3   Number of Firmware Slots
  [0:0] : 0     Firmware Slot 1 Read/Write

lpa       : 0x2f
  [6:6] : 0     Telemetry Log Data Area 4 Not Supported
  [5:5] : 0x1   LID 0x0, Scope of each command in LID 0x5, 0x12, 0x13 Supported
  [4:4] : 0     Persistent Event log Not Supported
  [3:3] : 0x1   Telemetry host/controller initiated log page Supported
  [2:2] : 0x1   Extended data for Get Log Page Supported
  [1:1] : 0x1   Command Effects Log Page Supported
  [0:0] : 0x1   SMART/Health Log Page per NS Supported

elpe      : 63
  [7:0] : 63 (0's based)        Error Log Page Entries (ELPE)

npss      : 4
  [7:0] : 4 (0's based) Number of Power States Support (NPSS)

avscc     : 0x1
  [0:0] : 0x1   Admin Vendor Specific Commands uses NVMe Format

apsta     : 0x1
  [0:0] : 0x1   Autonomous Power State Transitions Supported

wctemp    : 355
 [15:0] : 82°C (355 Kelvin)     Warning Composite Temperature Threshold (WCTEMP)

cctemp    : 358
 [15:0] : 85°C (358 Kelvin)     Critical Composite Temperature Threshold (CCTEMP)

mtfa      : 0
hmpre     : 0
hmmin     : 0
tnvmcap   : 2,000,398,934,016
[127:0] : 2,000,398,934,016
        Total NVM Capacity (TNVMCAP)

unvmcap   : 0
[127:0] : 0
        Unallocated NVM Capacity (UNVMCAP)

rpmbs     : 0
 [31:24]: 0     Access Size
 [23:16]: 0     Total Size
  [5:3] : 0     Authentication Method
  [2:0] : 0     Number of RPMB Units

edstt     : 35
dsto      : 0
fwug      : 0
kas       : 0
hctma     : 0x1
  [0:0] : 0x1   Host Controlled Thermal Management Supported

mntmt     : 318
 [15:0] : 45°C (318 Kelvin)     Minimum Thermal Management Temperature (MNTMT)

mxtmt     : 356
 [15:0] : 83°C (356 Kelvin)     Maximum Thermal Management Temperature (MXTMT)

sanicap   : 0x60000003
  [31:30] : 0x1 Media is not additionally modified after sanitize operation completes successfully
  [29:29] : 0x1 No-Deallocate After Sanitize bit in Sanitize command Not Supported
    [2:2] : 0   Overwrite Sanitize Operation Not Supported
    [1:1] : 0x1 Block Erase Sanitize Operation Supported
    [0:0] : 0x1 Crypto Erase Sanitize Operation Supported

hmminds   : 0
hmmaxd    : 0
nsetidmax : 0
endgidmax : 1
anatt     : 0
anacap    : 0
  [7:7] : 0     Non-zero group ID Not Supported
  [6:6] : 0     Group ID does change
  [4:4] : 0     ANA Change state Not Supported
  [3:3] : 0     ANA Persistent Loss state Not Supported
  [2:2] : 0     ANA Inaccessible state Not Supported
  [1:1] : 0     ANA Non-optimized state Not Supported
  [0:0] : 0     ANA Optimized state Not Supported

anagrpmax : 0
nanagrpid : 0
pels      : 0
domainid  : 0
megcap    : 0
sqes      : 0x66
  [7:4] : 0x6   Max SQ Entry Size (64)
  [3:0] : 0x6   Min SQ Entry Size (64)

cqes      : 0x44
  [7:4] : 0x4   Max CQ Entry Size (16)
  [3:0] : 0x4   Min CQ Entry Size (16)

maxcmd    : 256
nn        : 1
oncs      : 0x55
  [8:8] : 0     Copy Not Supported
  [7:7] : 0     Verify Not Supported
  [6:6] : 0x1   Timestamp Supported
  [5:5] : 0     Reservations Not Supported
  [4:4] : 0x1   Save and Select Supported
  [3:3] : 0     Write Zeroes Not Supported
  [2:2] : 0x1   Data Set Management Supported
  [1:1] : 0     Write Uncorrectable Not Supported
  [0:0] : 0x1   Compare Supported

fuses     : 0
  [0:0] : 0     Fused Compare and Write Not Supported

fna       : 0x7
  [3:3] : 0     Format NVM Broadcast NSID (FFFFFFFFh) Supported
  [2:2] : 0x1   Crypto Erase Supported as part of Secure Erase
  [1:1] : 0x1   Crypto Erase Applies to All Namespace(s)
  [0:0] : 0x1   Format Applies to All Namespace(s)

vwc       : 0x7
  [2:1] : 0x3   The Flush command supports NSID set to FFFFFFFFh
  [0:0] : 0x1   Volatile Write Cache Present

awun      : 1023
awupf     : 0
icsvscc   : 1
  [0:0] : 0x1   NVM Vendor Specific Commands uses NVMe Format

nwpc      : 0
  [2:2] : 0     Permanent Write Protect Not Supported
  [1:1] : 0     Write Protect Until Power Supply Not Supported
  [0:0] : 0     No Write Protect and Write Protect Namespace Not Supported

acwu      : 0
ocfs      : 0
  [1:1] : 0     Controller Copy Format 1h Not Supported
  [0:0] : 0     Controller Copy Format 0h Not Supported

sgls      : 0
 [15:8] : 0     SGL Descriptor Threshold
 [1:0]  : 0     Scatter-Gather Lists Not Supported

mnan      : 0
maxdna    : 0
maxcna    : 0
subnqn    : nqn.1994-11.com.samsung:nvme:990PRO:M.2:S6Z2NJ0W215164J     
ioccsz    : 0
iorcsz    : 0
icdoff    : 0
fcatt     : 0
  [0:0] : 0     Dynamic Controller Model

msdbd     : 0
ofcs      : 0
  [0:0] : 0     Disconnect command Not Supported

ps      0 : mp:9.39W operational enlat:0 exlat:0 rrt:0 rrl:0
            rwt:0 rwl:0 idle_power:- active_power:-
            active_power_workload:-
ps      1 : mp:9.39W operational enlat:0 exlat:200 rrt:1 rrl:1
            rwt:1 rwl:1 idle_power:- active_power:-
            active_power_workload:-
ps      2 : mp:9.39W operational enlat:0 exlat:1000 rrt:2 rrl:2
            rwt:2 rwl:2 idle_power:- active_power:-
            active_power_workload:-
ps      3 : mp:0.0400W non-operational enlat:2000 exlat:1200 rrt:3 rrl:3
            rwt:3 rwl:3 idle_power:- active_power:-
            active_power_workload:-
ps      4 : mp:0.0050W non-operational enlat:500 exlat:9500 rrt:4 rrl:4
            rwt:4 rwl:4 idle_power:- active_power:-
            active_power_workload:-
-------------------