> However, !guilty && ctx->reset_counter != adev->reset_counter does not > imply that the context was lost. > > The way I understand it, we should return AMDGPU_CTX_INNOCENT_RESET if > !guilty && ctx->vram_lost_counter != adev->vram_lost_counter. > > As far as I understand it, the case of !guilty && ctx->reset_counter > != adev->reset_counter && ctx->vram_lost_counter == > adev->vram_lost_counter should return AMDGPU_CTX_NO_RESET, because a > GPU reset occurred, but it didn't affect our context. I disagree on that. AMDGPU_CTX_INNOCENT_RESET just means what it does currently, there was a reset but we haven't been causing it. That the OpenGL extension is specified otherwise is unfortunate, but I think we shouldn't use that for the kernel interface here. Regards, Christian. Am 12.10.2017 um 10:44 schrieb Nicolai Hähnle: > I think we should stick to the plan where kernel contexts stay "stuck" > after a GPU reset. This is the most robust behavior for the kernel. > > Even if the OpenGL spec says that an OpenGL context can be re-used > without destroying and re-creating it, the UMD can take care of > re-creating the kernel context. > > This means amdgpu_ctx_query should *not* reset ctx->reset_counter. > > Cheers, > Nicolai > > > On 12.10.2017 10:41, Nicolai Hähnle wrote: >> Hi Monk, >> >> Thanks for the summary. Most of it looks good to me, though I can't >> speak to all the kernel internals. >> >> Just some comments: >> >> On 12.10.2017 10:03, Liu, Monk wrote: >>> lFor cs_submit() IOCTL: >>> >>> 1.check if current ctx been marked â??*guilty*â??and return >>> â??*ECANCELED*â?? if so. >>> >>> 2.set job->*vram_lost_counter* with adev->*vram_lost_counter*, and >>> return â??*ECANCELED*â?? if ctx->*vram_lost_counter* != >>> job->*vram_lost_counter* (Christian already submitted this patch) >>> >>> a)discussion: can we return â??ENODEVâ?? if vram_lost_counter mismatch ? >>> that way UMD know this context is under â??device lostâ?? >> >> My plan for UMD is to always query the VRAM lost counter when any >> kind of context lost situation is detected. So cs_submit() should >> return an error in this situation, but it could just be ECANCELED. We >> don't need to distinguish between different types of errors here. >> >> >>> lIntroduce a new IOCTL to let UMD query latest >>> adev->*vram_lost_counter*: >> >> Christian already sent a patch for this. >> >> >>> lFor amdgpu_ctx_query(): >>> >>> n*Donâ??t update ctx->reset_counter when querying this function, >>> otherwise the query result is not consistent * >> >> Hmm. I misremembered part of the spec, see below. >> >> >>> nSet out->state.reset_status to â??AMDGPU_CTX_GUILTY_RESETâ?? if the ctx >>> is â??*guilty*â??, no need to check â??ctx->reset_counterâ?? >> >> Agreed. >> >> >>> nSet out->state.reset_status to â??AMDGPU_CTX_INNOCENT_RESETâ?? *if the >>> ctx isnâ??t â??guiltyâ?? && ctx->reset_counter != adev->reset_counter * >> >> I disagree. The meaning of AMDGPU_CTX_*_RESET should reflect the >> corresponding enums in user space APIs. I don't know how it works in >> Vulkan, but in OpenGL, returning GL_INNOCENT_CONTEXT_RESET_ARB means >> that the context was lost. >> >> However, !guilty && ctx->reset_counter != adev->reset_counter does >> not imply that the context was lost. >> >> The way I understand it, we should return AMDGPU_CTX_INNOCENT_RESET >> if !guilty && ctx->vram_lost_counter != adev->vram_lost_counter. >> >> As far as I understand it, the case of !guilty && ctx->reset_counter >> != adev->reset_counter && ctx->vram_lost_counter == >> adev->vram_lost_counter should return AMDGPU_CTX_NO_RESET, because a >> GPU reset occurred, but it didn't affect our context. >> >> I unfortunately noticed another subtlety while re-reading the OpenGL >> spec. OpenGL says that the OpenGL context itself does *not* have to >> be re-created in order to recover from the reset. Re-creating all >> objects in the context is sufficient. >> >> I believe this is the original motivation for why amdgpu_ctx_query() >> will reset the ctx->reset_counter. >> >> For Mesa, it's still okay if the kernel keeps blocking submissions as >> we can just recreate the kernel context. But OrcaGL is also affected. >> >> Does anybody know off-hand where the relevant parts of the Vulkan >> spec are? I didn't actually find anything in a quick search. >> >> >> [snip] >>> For UMD behavior we still have something need to consider: >>> >>> If MESA creates a new context from an old context (share list?? Iâ??m >>> not familiar with UMD , David Mao shall have some discuss on it with >>> Nicolai), the new created contextâ??s vram_lost_counter >>> >>> And reset_counter shall all be ported from that old context , >>> otherwise CS_SUBMIT will not block it which isnâ??t correct >> >> The kernel doesn't have to do anything for this, it is entirely the >> UMD's responsibility. All UMD needs from KMD is the function for >> querying the vram_lost_counter. >> >> Cheers, >> Nicolai >> >> >>> >>> Need your feedback, thx >>> >>> *From:*amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] *On >>> Behalf Of *Liu, Monk >>> *Sent:* 2017å¹´10æ??11æ?¥13:34 >>> *To:* Koenig, Christian <Christian.Koenig at amd.com>; Haehnle, Nicolai >>> <Nicolai.Haehnle at amd.com>; Olsak, Marek <Marek.Olsak at amd.com>; >>> Deucher, Alexander <Alexander.Deucher at amd.com> >>> *Cc:* Ramirez, Alejandro <Alejandro.Ramirez at amd.com>; >>> amd-gfx at lists.freedesktop.org; Filipas, Mario >>> <Mario.Filipas at amd.com>; Ding, Pixel <Pixel.Ding at amd.com>; Li, >>> Bingley <Bingley.Li at amd.com>; Jiang, Jerry (SW) <Jerry.Jiang at amd.com> >>> *Subject:* TDR and VRAM lost handling in KMD: >>> >>> Hi Christian & Nicolai, >>> >>> We need to achieve some agreements on what should MESA/UMD do and >>> what should KMD do, *please give your comments with **â??okayâ??or >>> â??Noâ??and your idea on below items,* >>> >>> lWhen a job timed out (set from lockup_timeout kernel parameter), >>> What KMD should do in TDR routine : >>> >>> 1.Update adev->*gpu_reset_counter*, and stop scheduler first, >>> (*gpu_reset_counter* is used to force vm flush after GPU reset, out >>> of this threadâ??s scope so no more discussion on it) >>> >>> 2.Set its fence error status to â??*ETIME*â??, >>> >>> 3.Find the entity/ctx behind this job, and set this ctx as â??*guilty*â?? >>> >>> 4.Kick out this job from schedulerâ??s mirror list, so this job wonâ??t >>> get re-scheduled to ring anymore. >>> >>> 5.Kick out all jobs in this â??guiltyâ??ctxâ??s KFIFO queue, and set all >>> their fence status to â??*ECANCELED*â?? >>> >>> *6.*Force signal all fences that get kicked out by above two >>> steps,*otherwise UMD will block forever if waiting on those fences* >>> >>> 7.Do gpu reset, which is can be some callbacks to let bare-metal and >>> SR-IOV implement with their favor style >>> >>> 8.After reset, KMD need to aware if the VRAM lost happens or not, >>> bare-metal can implement some function to judge, while for SR-IOV I >>> prefer to read it from GIM side (for initial version we consider >>> itâ??s always VRAM lost, till GIM side change aligned) >>> >>> 9.If VRAM lost not hit, continue, otherwise: >>> >>> a)Update adev->*vram_lost_counter*, >>> >>> b)Iterate over all living ctx, and set all ctx as â??*guilty*â??since >>> VRAM lost actually ruins all VRAM contents >>> >>> c)Kick out all jobs in all ctxâ??s KFIFO queue, and set all their >>> fence status to â??*ECANCELDED*â?? >>> >>> 10.Do GTT recovery and VRAM page tables/entries recovery (optional, >>> do we need it ???) >>> >>> 11.Re-schedule all JOBs remains in mirror list to ring again and >>> restart scheduler (for VRAM lost case, no JOB will re-scheduled) >>> >>> lFor cs_wait() IOCTL: >>> >>> After it found fence signaled, it should check with >>> *â??dma_fence_get_statusâ?? *to see if there is error there, >>> >>> And return the error status of fence >>> >>> lFor cs_wait_fences() IOCTL: >>> >>> Similar with above approach >>> >>> lFor cs_submit() IOCTL: >>> >>> It need to check if current ctx been marked as â??*guilty*â??and return >>> â??*ECANCELED*â??if so >>> >>> lIntroduce a new IOCTL to let UMD query *vram_lost_counter*: >>> >>> This way, UMD can also block app from submitting, like @Nicolai >>> mentioned, we can cache one copy of *vram_lost_counter* when >>> enumerate physical device, and deny all >>> >>> gl-context from submitting if the counter queried bigger than that >>> one cached in physical device. (looks a little overkill to me, but >>> easy to implement ) >>> >>> UMD can also return error to APP when creating gl-context if found >>> current queried*vram_lost_counter *bigger than that one cached in >>> physical device. >>> >>> BTW: I realized that gl-context is a little different with kernelâ??s >>> context. Because for kernel. BO is not related with context but only >>> with FD, while in UMD, BO have a backend >>> >>> gl-context, so block submitting in UMD layer is also needed although >>> KMD will do its job as bottom line >>> >>> lBasically â??vram_lost_counterâ??is exposure by kernel to let UMD take >>> the control of robust extension feature, it will be UMDâ??s call to >>> move, KMD only deny â??guiltyâ??context from submitting >>> >>> Need your feedback, thx >>> >>> Weâ??d better make TDR feature landed ASAP >>> >>> BR Monk >>> >> >
