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From: Grodzovsky, Andrey <andrey.grodzov...@amd.com>
Sent: Saturday, November 30, 2019 12:22 AM
To: Ma, Le <le...@amd.com>; amd-gfx@lists.freedesktop.org
Cc: Chen, Guchun <guchun.c...@amd.com>; Zhou1, Tao <tao.zh...@amd.com>; 
Deucher, Alexander <alexander.deuc...@amd.com>; Li, Dennis <dennis...@amd.com>; 
Zhang, Hawking <hawking.zh...@amd.com>
Subject: Re: [PATCH 07/10] drm/amdgpu: add concurrent baco reset support for 
XGMI



On 11/28/19 4:00 AM, Ma, Le wrote:





-----Original Message-----
From: Grodzovsky, Andrey 
<andrey.grodzov...@amd.com><mailto:andrey.grodzov...@amd.com>
Sent: Wednesday, November 27, 2019 11:46 PM
To: Ma, Le <le...@amd.com><mailto:le...@amd.com>; 
amd-gfx@lists.freedesktop.org<mailto:amd-gfx@lists.freedesktop.org>
Cc: Chen, Guchun <guchun.c...@amd.com><mailto:guchun.c...@amd.com>; Zhou1, Tao 
<tao.zh...@amd.com><mailto:tao.zh...@amd.com>; Deucher, Alexander 
<alexander.deuc...@amd.com><mailto:alexander.deuc...@amd.com>; Li, Dennis 
<dennis...@amd.com><mailto:dennis...@amd.com>; Zhang, Hawking 
<hawking.zh...@amd.com><mailto:hawking.zh...@amd.com>
Subject: Re: [PATCH 07/10] drm/amdgpu: add concurrent baco reset support for 
XGMI





On 11/27/19 4:15 AM, Le Ma wrote:

> Currently each XGMI node reset wq does not run in parrallel because

> same work item bound to same cpu runs in sequence. So change to bound

> the xgmi_reset_work item to different cpus.



It's not the same work item, see more bellow





>

> XGMI requires all nodes enter into baco within very close proximity

> before any node exit baco. So schedule the xgmi_reset_work wq twice

> for enter/exit baco respectively.

>

> The default reset code path and methods do not change for vega20 production:

>    - baco reset without xgmi/ras

>    - psp reset with xgmi/ras

>

> To enable baco for XGMI/RAS case, both 2 conditions below are needed:

>    - amdgpu_ras_enable=2

>    - baco-supported smu firmware

>

> The case that PSP reset and baco reset coexist within an XGMI hive is

> not in the consideration.

>

> Change-Id: I9c08cf90134f940b42e20d2129ff87fba761c532

> Signed-off-by: Le Ma <le...@amd.com<mailto:le...@amd.com>>

> ---

>   drivers/gpu/drm/amd/amdgpu/amdgpu.h        |  2 +

>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 78 
> ++++++++++++++++++++++++++----

>   2 files changed, 70 insertions(+), 10 deletions(-)

>

> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h

> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h

> index d120fe5..08929e6 100644

> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h

> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h

> @@ -998,6 +998,8 @@ struct amdgpu_device {

>          int                                           pstate;

>          /* enable runtime pm on the device */

>          bool                            runpm;

> +

> +      bool                                        in_baco;

>   };

>

>   static inline struct amdgpu_device *amdgpu_ttm_adev(struct

> ttm_bo_device *bdev) diff --git

> a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

> index bd387bb..71abfe9 100644

> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

> @@ -2654,7 +2654,13 @@ static void amdgpu_device_xgmi_reset_func(struct 
> work_struct *__work)

>          struct amdgpu_device *adev =

>                      container_of(__work, struct amdgpu_device, 
> xgmi_reset_work);

>

> -       adev->asic_reset_res =  amdgpu_asic_reset(adev);

> +      if (amdgpu_asic_reset_method(adev) == AMD_RESET_METHOD_BACO)

> +                  adev->asic_reset_res = (adev->in_baco == false) ?

> +                                          
> amdgpu_device_baco_enter(adev->ddev) :

> +                                          
> amdgpu_device_baco_exit(adev->ddev);

> +      else

> +                  adev->asic_reset_res = amdgpu_asic_reset(adev);

> +

>          if (adev->asic_reset_res)

>                      DRM_WARN("ASIC reset failed with error, %d for drm dev, 
> %s",

>                                   adev->asic_reset_res, adev->ddev->unique); 
> @@ -3796,6 +3802,7 @@

> static int amdgpu_do_asic_reset(struct amdgpu_hive_info *hive,

>          struct amdgpu_device *tmp_adev = NULL;

>          bool need_full_reset = *need_full_reset_arg, vram_lost = false;

>          int r = 0;

> +      int cpu = smp_processor_id();

>

>          /*

>           * ASIC reset has to be done on all HGMI hive nodes ASAP @@

> -3803,21 +3810,24 @@ static int amdgpu_do_asic_reset(struct amdgpu_hive_info 
> *hive,

>           */

>          if (need_full_reset) {

>                      list_for_each_entry(tmp_adev, device_list_handle, 
> gmc.xgmi.head) {

> -                               /* For XGMI run all resets in parallel to 
> speed up the process */

> +                              /*

> +                              * For XGMI run all resets in parallel to speed 
> up the

> +                              * process by scheduling the highpri wq on 
> different

> +                              * cpus. For XGMI with baco reset, all nodes 
> must enter

> +                              * baco within close proximity before anyone 
> exit.

> +                              */

>                                  if (tmp_adev->gmc.xgmi.num_physical_nodes > 
> 1) {

> -                                           if 
> (!queue_work(system_highpri_wq, &tmp_adev->xgmi_reset_work))





Note that tmp_adev->xgmi_reset_work (the work item) is per device in XGMI hive 
and not the same work item. So I don't see why you need to explicitly queue 
them on different CPUs, they should run in parallel already.



Andrey



[Le]: It's also beyond my understanding that the 2 node reset work items 
scheduled to same cpu does not run in parallel. But from the experiment result 
in my side, the 2nd work item always run after 1st work item finished. Based on 
this result, I changed to queue them on different CPUs to make sure more XGMI 
nodes case to run in parallel, because baco requires all nodes enter baco 
within very close proximity.



The experiment code is as following for your reference. When card0 worker 
running, card1 worker is not observed to run.



The code bellow will only test that they don't run concurrently - but this 
doesn't mean they don't run on different CPUs and threads,I don't have an XGMI 
setup at hand to test this theory but what if there is some locking dependency 
between them that serializes their execution ? Can you just add a one line 
print inside amdgpu_device_xgmi_reset_func that prints CPU id, thread name/id 
and card number ?

Andrey

[Le]: I checked if directly use queue_work() several times, the same CPU thread 
will be used. And the worker per CPU will execute the item one by one. Our goal 
here is to make the xgmi_reset_func run concurrently for XGMI BACO case. That's 
why I schedule them on different CPUs to run parallelly. And I can share the 
XGMI system with you if you'd like to verify more.



+atomic_t card0_in_baco = ATOMIC_INIT(0);

+atomic_t card1_in_baco = ATOMIC_INIT(0);

+

static void amdgpu_device_xgmi_reset_func(struct work_struct *__work)

{

        struct amdgpu_device *adev =

                container_of(__work, struct amdgpu_device, xgmi_reset_work);



+       printk("lema1: card 0x%x goes into reset wq\n", 
adev->pdev->bus->number);

+       if (adev->pdev->bus->number == 0x7) {

+               atomic_set(&card1_in_baco, 1);

+               printk("lema1: card1 in baco from card1 view\n");

+       }

+

        if (amdgpu_asic_reset_method(adev) == AMD_RESET_METHOD_BACO)

               adev->asic_reset_res = (adev->in_baco == false) ?

                                amdgpu_device_baco_enter(adev->ddev) :

@@ -2664,6 +2673,23 @@ static void amdgpu_device_xgmi_reset_func(struct 
work_struct *__work)

        if (adev->asic_reset_res)

                DRM_WARN("ASIC reset failed with error, %d for drm dev, %s",

                         adev->asic_reset_res, adev->ddev->unique);

+

+       if (adev->pdev->bus->number == 0x4) {

+               atomic_set(&card0_in_baco, 1);

+               printk("lema1: card0 in baco from card0 view\n");

+

+               while (true)

+                       if (!!atomic_read(&card1_in_baco))

+                               break;

+               printk("lema1: card1 in baco from card0 view\n");

+       }

+

+       if (adev->pdev->bus->number == 0x7) {

+               while (true)

+                       if (!!atomic_read(&card0_in_baco))

+                               break;

+               printk("lema1: card0 in baco from card1 view\n");

+       }



> +                                          if (!queue_work_on(cpu, 
> system_highpri_wq,

> +                                                                     
> &tmp_adev->xgmi_reset_work))

>                                                          r = -EALREADY;

> +                                          cpu = cpumask_next(cpu, 
> cpu_online_mask);

>                                  } else

>                                              r = amdgpu_asic_reset(tmp_adev);

> -

> -                               if (r) {

> -                                           DRM_ERROR("ASIC reset failed with 
> error, %d for drm dev, %s",

> -                                                       r, 
> tmp_adev->ddev->unique);

> +                              if (r)

>                                              break;

> -                               }

>                      }

>

> -                   /* For XGMI wait for all PSP resets to complete before 
> proceed */

> +                  /* For XGMI wait for all work to complete before proceed */

>                      if (!r) {

>                                  list_for_each_entry(tmp_adev, 
> device_list_handle,

>                                                              gmc.xgmi.head) {

> @@ -3826,11 +3836,59 @@ static int amdgpu_do_asic_reset(struct 
> amdgpu_hive_info *hive,

>                                                          r = 
> tmp_adev->asic_reset_res;

>                                                          if (r)

>                                                                      break;

> +                                                      
> if(AMD_RESET_METHOD_BACO ==

> +                                                         
> amdgpu_asic_reset_method(tmp_adev))

> +                                                                  
> tmp_adev->in_baco = true;

>                                              }

>                                  }

>                      }

> -       }

>

> +                  /*

> +                  * For XGMI with baco reset, need exit baco phase by 
> scheduling

> +                  * xgmi_reset_work one more time. PSP reset skips this 
> phase.

> +                  * Not assume the situation that PSP reset and baco reset

> +                  * coexist within an XGMI hive.

> +                  */

> +

> +                  if (!r) {

> +                              cpu = smp_processor_id();

> +                              list_for_each_entry(tmp_adev, 
> device_list_handle,

> +                                                          gmc.xgmi.head) {

> +                                          if 
> (tmp_adev->gmc.xgmi.num_physical_nodes > 1

> +                                              && AMD_RESET_METHOD_BACO ==

> +                                              
> amdgpu_asic_reset_method(tmp_adev)) {

> +                                                      if (!queue_work_on(cpu,

> +                                                                  
> system_highpri_wq,

> +                                                                  
> &tmp_adev->xgmi_reset_work))

> +                                                                  r = 
> -EALREADY;

> +                                                      if (r)

> +                                                                  break;

> +                                                      cpu = 
> cpumask_next(cpu, cpu_online_mask);

> +                                          }

> +                              }

> +                  }

> +

> +                  if (!r) {

> +                              list_for_each_entry(tmp_adev, 
> device_list_handle,

> +                                                          gmc.xgmi.head) {

> +                                          if 
> (tmp_adev->gmc.xgmi.num_physical_nodes > 1

> +                                              && AMD_RESET_METHOD_BACO ==

> +                                              
> amdgpu_asic_reset_method(tmp_adev)) {

> +                                                      
> flush_work(&tmp_adev->xgmi_reset_work);

> +                                                      r = 
> tmp_adev->asic_reset_res;

> +                                                      if (r)

> +                                                                  break;

> +                                                      tmp_adev->in_baco = 
> false;

> +                                          }

> +                              }

> +                  }

> +

> +                  if (r) {

> +                              DRM_ERROR("ASIC reset failed with error, %d 
> for drm dev, %s",

> +                                          r, tmp_adev->ddev->unique);

> +                              goto end;

> +                  }

> +      }

>

>          list_for_each_entry(tmp_adev, device_list_handle, gmc.xgmi.head) {

>                      if (need_full_reset) {
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