Call for testers with NVMe

I have a question, if you don't mind.

Below I provide my SSD NVME device PCIe configuration, from which one
can find that the device works at 8GT/s by x4 lanes, max theoretical
throughput is: 8GT/s*4*(128/130)/8 = 3.94 GB/sec. When I run
"nvmecontrol perftest" it gives me figures I don't know how to
interpret, something from 205 MB/s to 1079 MB/s, which is way too low.
In comparison, dd command gives more than 2000 MB/s on same device and
that is quite close to my feelings. ;) Can somebody please comment on
what "nvmecontrol perftest" does, how to consider its result and why it
differs so much from dd ? The man page on nvmecontrol is very scarce
about perftest option.

root@megamini:/home/rz # nvmecontrol perftest -n 4 -o read -s 4096 -t 30
nvme0ns1
Threads: 4 Size: 4096 READ Time: 30 IO/s: 52715 MB/s: 205

root@megamini:/home/rz # nvmecontrol perftest -n 4 -o read -s 81920 -t
30 nvme0ns1
Threads: 4 Size: 81920 READ Time: 30 IO/s: 13815 MB/s: 1079

root@megamini:/home/rz # lspci -vv -s 0:4:0
04:00.0 Non-Volatile memory controller: Biwin Storage Technology Co.,
Ltd. HP EX900 Plus NVMe SSD (DRAM-less) (rev 01) (prog-if 02 [NVM
Express])
Subsystem: Biwin Storage Technology Co., Ltd. HP EX900 Plus NVMe SSD
(DRAM-less)
Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B- DisINTx+
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- >SERR- <PERR- INTx-
Latency: 0, Cache Line Size: 64 bytes
Interrupts: pin B disabled
Region 0: Memory at dc900000 (64-bit, non-prefetchable)
Capabilities: [40] Power Management version 3
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
PME(D0+,D1-,D2-,D3hot+,D3cold+)
Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [50] MSI: Enable- Count=1/32 Maskable+ 64bit+
Address: 0000000000000000 Data: 0000
Masking: 00000000 Pending: 00000000
Capabilities: [70] Express (v2) Endpoint, IntMsgNum 31
DevCap: MaxPayload 512 bytes, PhantFunc 0, Latency L0s unlimited, L1
unlimited
ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset+ SlotPowerLimit 75W
TEE-IO-
DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+ FLReset-
MaxPayload 256 bytes, MaxReadReq 512 bytes
DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr+ TransPend-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L1 <64us
ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp+
LnkCtl: ASPM Disabled; RCB 64 bytes, LnkDisable- CommClk+
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- FltModeDis-
LnkSta: Speed 8GT/s, Width x4
TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR+
10BitTagComp- 10BitTagReq- OBFF Via message, ExtFmt- EETLPPrefix-
EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
FRS- TPHComp- ExtTPHComp-
AtomicOpsCap: 32bit- 64bit- 128bitCAS-
DevCtl2: Completion Timeout: 16ms to 55ms, TimeoutDis-
AtomicOpsCtl: ReqEn-
IDOReq- IDOCompl- LTR+ EmergencyPowerReductionReq-
10BitTagReq- OBFF Disabled, EETLPPrefixBlk-
LnkCap2: Supported Link Speeds: 2.5-8GT/s, Crosslink- Retimer-
2Retimers- DRS-
LnkCtl2: Target Link Speed: 8GT/s, EnterCompliance- SpeedDis-
Transmit Margin: Normal Operating Range, EnterModifiedCompliance-
ComplianceSOS-
Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete+
EqualizationPhase1+
EqualizationPhase2+ EqualizationPhase3+ LinkEqualizationRequest-
Retimer- 2Retimers- CrosslinkRes: unsupported, FltMode-
Capabilities: [b0] MSI-X: Enable+ Count=9 Masked-
Vector table: BAR=0 offset=00003000
PBA: BAR=0 offset=00002000
Capabilities: [100 v2] Advanced Error Reporting
UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP-
ECRC- UnsupReq- ACSViol- UncorrIntErr- BlockedTLP- AtomicOpBlocked-
TLPBlockedErr-
PoisonTLPBlocked- DMWrReqBlocked- IDECheck- MisIDETLP- PCRC_CHECK-
TLPXlatBlocked-
UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP-
ECRC- UnsupReq- ACSViol- UncorrIntErr+ BlockedTLP- AtomicOpBlocked-
TLPBlockedErr-
PoisonTLPBlocked- DMWrReqBlocked- IDECheck- MisIDETLP- PCRC_CHECK-
TLPXlatBlocked-
UESvrt: DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+
MalfTLP+
ECRC- UnsupReq- ACSViol- UncorrIntErr+ BlockedTLP- AtomicOpBlocked-
TLPBlockedErr-
PoisonTLPBlocked- DMWrReqBlocked- IDECheck- MisIDETLP- PCRC_CHECK-
TLPXlatBlocked-
CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
CorrIntErr- HeaderOF-
CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
CorrIntErr+ HeaderOF+
AERCap: First Error Pointer: 00, ECRCGenCap+ ECRCGenEn- ECRCChkCap+
ECRCChkEn-
MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
HeaderLog: 00000000 00000000 00000000 00000000
Capabilities: [148 v1] Device Serial Number 00-00-00-00-00-00-00-00
Capabilities: [158 v1] Alternative Routing-ID Interpretation (ARI)
ARICap: MFVC- ACS+, Next Function: 0
ARICtl: MFVC- ACS-, Function Group: 0
Capabilities: [168 v1] Secondary PCI Express
LnkCtl3: LnkEquIntrruptEn- PerformEqu-
LaneErrStat: 0
Capabilities: [1d4 v1] Latency Tolerance Reporting
Max snoop latency: 1048576ns
Max no snoop latency: 1048576ns
Capabilities: [1dc v1] L1 PM Substates
L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+
L1_PM_Substates+
PortCommonModeRestoreTime=10us PortTPowerOnTime=14us
L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2- ASPM_L1.1-
T_CommonMode=0us LTR1.2_Threshold=32768ns
L1SubCtl2: T_PwrOn=0us
Capabilities: [1ec v1] Vendor Specific Information: ID=0002 Rev=4
Len=100 <?>
Capabilities: [2ec v1] Vendor Specific Information: ID=0001 Rev=1
Len=038 <?>

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Regards,
Ruslan