Hi Vetter, On Wed, Sep 04, 2019 at 01:20:29PM +0200, Daniel Vetter wrote: > On Wed, Sep 4, 2019 at 1:15 PM Dave Airlie <airlied@xxxxxxxxx> wrote: > > > > On Wed, 4 Sep 2019 at 19:17, Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > > On Wed, Sep 4, 2019 at 10:35 AM Feng Tang <feng.tang@xxxxxxxxx> wrote: > > > > > > > > Hi Daniel, > > > > > > > > On Wed, Sep 04, 2019 at 10:11:11AM +0200, Daniel Vetter wrote: > > > > > On Wed, Sep 4, 2019 at 8:53 AM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > > > > > > > > > > > > Hi > > > > > > > > > > > > Am 04.09.19 um 08:27 schrieb Feng Tang: > > > > > > >> Thank you for testing. But don't get too excited, because the patch > > > > > > >> simulates a bug that was present in the original mgag200 code. A > > > > > > >> significant number of frames are simply skipped. That is apparently the > > > > > > >> reason why it's faster. > > > > > > > > > > > > > > Thanks for the detailed info, so the original code skips time-consuming > > > > > > > work inside atomic context on purpose. Is there any space to optmise it? > > > > > > > If 2 scheduled update worker are handled at almost same time, can one be > > > > > > > skipped? > > > > > > > > > > > > To my knowledge, there's only one instance of the worker. Re-scheduling > > > > > > the worker before a previous instance started, will not create a second > > > > > > instance. The worker's instance will complete all pending updates. So in > > > > > > some way, skipping workers already happens. > > > > > > > > > > So I think that the most often fbcon update from atomic context is the > > > > > blinking cursor. If you disable that one you should be back to the old > > > > > performance level I think, since just writing to dmesg is from process > > > > > context, so shouldn't change. > > > > > > > > Hmm, then for the old driver, it should also do the most update in > > > > non-atomic context? > > > > > > > > One other thing is, I profiled that updating a 3MB shadow buffer needs > > > > 20 ms, which transfer to 150 MB/s bandwidth. Could it be related with > > > > the cache setting of DRM shadow buffer? say the orginal code use a > > > > cachable buffer? > > > > > > Hm, that would indicate the write-combining got broken somewhere. This > > > should definitely be faster. Also we shouldn't transfer the hole > > > thing, except when scrolling ... > > > > First rule of fbcon usage, you are always effectively scrolling. > > > > Also these devices might be on a PCIE 1x piece of wet string, not sure > > if the numbers reflect that. > > pcie 1x 1.0 is 250MB/s, so yeah with a bit of inefficiency and > overhead not entirely out of the question that 150MB/s is actually the > hw limit. If it's really pcie 1x 1.0, no idea where to check that. > Also might be worth to double-check that the gpu pci bar is listed as > wc in debugfs/x86/pat_memtype_list. Here is some dump of the device info and the pat_memtype_list, while it is running other 0day task: controller info ================= 03:00.0 VGA compatible controller: Matrox Electronics Systems Ltd. MGA G200e [Pilot] ServerEngines (SEP1) (rev 05) (prog-if 00 [VGA controller]) Subsystem: Intel Corporation MGA G200e [Pilot] ServerEngines (SEP1) 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- Interrupt: pin A routed to IRQ 16 NUMA node: 0 Region 0: Memory at d0000000 (32-bit, prefetchable) [size=16M] Region 1: Memory at d1800000 (32-bit, non-prefetchable) [size=16K] Region 2: Memory at d1000000 (32-bit, non-prefetchable) [size=8M] Expansion ROM at 000c0000 [disabled] [size=128K] Capabilities: [dc] Power Management version 2 Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-) Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME- Capabilities: [e4] Express (v1) Legacy Endpoint, MSI 00 DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us ExtTag- AttnBtn- AttnInd- PwrInd- RBE- FLReset- DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported- RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop- MaxPayload 128 bytes, MaxReadReq 128 bytes DevSta: CorrErr+ UncorrErr+ FatalErr- UnsuppReq+ AuxPwr- TransPend- LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s, Exit Latency L0s <64ns, L1 <1us ClockPM- Surprise- LLActRep- BwNot- ASPMOptComp- LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+ ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- Capabilities: [54] MSI: Enable- Count=1/1 Maskable- 64bit- Address: 00000000 Data: 0000 Kernel driver in use: mgag200 Kernel modules: mgag200 Related pat setting =================== uncached-minus @ 0xc0000000-0xc0001000 uncached-minus @ 0xc0000000-0xd0000000 uncached-minus @ 0xc0008000-0xc0009000 uncached-minus @ 0xc0009000-0xc000a000 uncached-minus @ 0xc0010000-0xc0011000 uncached-minus @ 0xc0011000-0xc0012000 uncached-minus @ 0xc0012000-0xc0013000 uncached-minus @ 0xc0013000-0xc0014000 uncached-minus @ 0xc0018000-0xc0019000 uncached-minus @ 0xc0019000-0xc001a000 uncached-minus @ 0xc001a000-0xc001b000 write-combining @ 0xd0000000-0xd0300000 write-combining @ 0xd0000000-0xd1000000 uncached-minus @ 0xd1800000-0xd1804000 uncached-minus @ 0xd1900000-0xd1980000 uncached-minus @ 0xd1980000-0xd1981000 uncached-minus @ 0xd1a00000-0xd1a80000 uncached-minus @ 0xd1a80000-0xd1a81000 uncached-minus @ 0xd1f10000-0xd1f11000 uncached-minus @ 0xd1f11000-0xd1f12000 uncached-minus @ 0xd1f12000-0xd1f13000 Host bridge info ================ 00:00.0 Host bridge: Intel Corporation Device 7853 Subsystem: Intel Corporation Device 0000 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- Interrupt: pin A routed to IRQ 0 NUMA node: 0 Capabilities: [90] Express (v2) Root Port (Slot-), MSI 00 DevCap: MaxPayload 128 bytes, PhantFunc 0 ExtTag- RBE+ DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported- RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop- MaxPayload 128 bytes, MaxReadReq 128 bytes DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend- LnkCap: Port #0, Speed 2.5GT/s, Width x4, ASPM L1, Exit Latency L0s <512ns, L1 <4us ClockPM- Surprise+ LLActRep+ BwNot+ ASPMOptComp+ LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk- ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- LnkSta: Speed unknown, Width x0, TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt- RootCtl: ErrCorrectable+ ErrNon-Fatal+ ErrFatal+ PMEIntEna- CRSVisible- RootCap: CRSVisible- RootSta: PME ReqID 0000, PMEStatus- PMEPending- DevCap2: Completion Timeout: Range BCD, TimeoutDis+, LTR-, OBFF Not Supported ARIFwd- DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled ARIFwd- LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis- Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS- Compliance De-emphasis: -6dB LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete-, EqualizationPhase1- EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest- Capabilities: [e0] 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: [100 v1] Vendor Specific Information: ID=0002 Rev=0 Len=00c <?> Capabilities: [144 v1] Vendor Specific Information: ID=0004 Rev=1 Len=03c <?> Capabilities: [1d0 v1] Vendor Specific Information: ID=0003 Rev=1 Len=00a <?> Capabilities: [250 v1] #19 Capabilities: [280 v1] Vendor Specific Information: ID=0005 Rev=3 Len=018 <?> Capabilities: [298 v1] Vendor Specific Information: ID=0007 Rev=0 Len=024 <?> Thanks, Feng > > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
