From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B934C3A5A5 for ; Thu, 5 Sep 2019 10:38:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2D2F22CF7 for ; Thu, 5 Sep 2019 10:38:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="T0AQp8Z6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387922AbfIEKiB (ORCPT ); Thu, 5 Sep 2019 06:38:01 -0400 Received: from mail-oi1-f194.google.com ([209.85.167.194]:46576 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726137AbfIEKiB (ORCPT ); Thu, 5 Sep 2019 06:38:01 -0400 Received: by mail-oi1-f194.google.com with SMTP id x7so1357065oie.13 for ; Thu, 05 Sep 2019 03:37:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Tv5zv7d3FEtwudjYamqn7+k4/1WeuNjqzNifKb9iPcY=; b=T0AQp8Z6RlhSgmRazaWOtGrXwEZFngAVq5L0iDAp/nE+T+zk/K2ldKZthPSxto3kNq pKIFAkUcbIo3USBodDrY/A7J3mHTqXghyzi4cB2P7TiEgVCNCPVEWxTCGGovSOppxDkB ib8mQjcIe+on2cK1tbVouERXOoQfERCy5SrDA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Tv5zv7d3FEtwudjYamqn7+k4/1WeuNjqzNifKb9iPcY=; b=tustCnhpYBIuzRgX4SasqVjK1x5TuhReMPW361fC5wjn52qPK3cX7Q6V1PxQIYOzb0 ezGdFbiuldlgkARBcGJp64mxdOKRtp5JPR/iSWCTzm1JXDNuxBJUFKaxCC6rNBZYcokI hlkejZO47rVU0ZebVFo+oXtT3vRf46+wDBx4nFvfEII8d0n09KR7+iovnzfNDdqGoIlp TL9RA0/fpISTVckLQqoPtH51sSbg4mmiNWlYyAKAZY9gH5wtIOXrQXpFVQ9CzbLcKmSl C2flnZoClXADkidcnt0XAWO8qQxzdQC7EAn2OuOJyR3dOG8BPIvXF9lWFW9bLWvTB1AB bdag== X-Gm-Message-State: APjAAAXk21hWsbHVBGZIBzhkBeqO4fQHggVPJvRrqu/PNXYwttwxVzzH 7/LZZZ3A4Q8rh98Ydkp4PVseoCIXHtTDKaFMrFicSg== X-Google-Smtp-Source: APXvYqypOysP5N8fdDTTUQZWV9ARI/nvkJSqknhAHdDvXyc190CkNaJJMrDjJli8RDQMWmr0wUQ5JzeCFIcVsGrk3qw= X-Received: by 2002:aca:5697:: with SMTP id k145mr1808438oib.101.1567679879301; Thu, 05 Sep 2019 03:37:59 -0700 (PDT) MIME-Version: 1.0 References: <44029e80-ba00-8246-dec0-fda122d53f5e@suse.de> <90e78ce8-d46a-5154-c324-a05aa1743c98@intel.com> <2e1b4d65-d477-f571-845d-fa0a670859af@suse.de> <20190904062716.GC5541@shbuild999.sh.intel.com> <72c33bf1-9184-e24a-c084-26d9c8b6f9b7@suse.de> <20190904083558.GD5541@shbuild999.sh.intel.com> <20190905065917.GE5541@shbuild999.sh.intel.com> In-Reply-To: <20190905065917.GE5541@shbuild999.sh.intel.com> From: Daniel Vetter Date: Thu, 5 Sep 2019 12:37:47 +0200 Message-ID: Subject: Re: [LKP] [drm/mgag200] 90f479ae51: vm-scalability.median -18.8% regression To: Feng Tang Cc: Dave Airlie , Stephen Rothwell , Rong Chen , =?UTF-8?Q?Michel_D=C3=A4nzer?= , Linux Kernel Mailing List , dri-devel , Thomas Zimmermann , LKP Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 5, 2019 at 8:58 AM Feng Tang wrote: > > 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 wrote: > > > > > > On Wed, 4 Sep 2019 at 19:17, Daniel Vetter wrote: > > > > > > > > On Wed, Sep 4, 2019 at 10:35 AM Feng Tang 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 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: Looks all good, I guess Dave is right with this probably only being a real slow, real old pcie link, plus maybe some inefficiencies in the mapping. Your 150MB/s, was that just the copy, or did you include all the setup/map/unmap/teardown too in your measurement in the trace? -Daniel > > 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- SERR- 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+ SERR- 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 -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch