Re: [PATCH] drm/amd/amdgpu: add tracing of kernel DMA mappings and enable on init (v2)

Tue, 15 Aug 2017 04:23:19 -0700 

Am 14.08.2017 um 13:37 schrieb Tom St Denis:

This patch adds trace points to the amdgpu bo_kmap/bo/kunmap functions
which capture internal allocations.

(v2): Simply add a sleep to the init.  Users can use this script to
load with map debugging enabled:

    #!/bin/bash
    modprobe amdgpu map_debug=1 &
    sleep 1
    echo 1 > 
/sys/kernel/debug/tracing/events/amdgpu/amdgpu_ttm_tt_unpopulate/enable
    echo 1 > 
/sys/kernel/debug/tracing/events/amdgpu/amdgpu_ttm_tt_populate/enable
I've just realized that there is a far simpler method than that or enabling trace points using the module command line.
Assuming your GPU is PCI device 01:00.0 connected through bridge 00:02.1 (use lspci -t to figure the connection out): 

# Temporary remove the PCIe device from the bus
echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/remove
# Load amdgpu, this allows you to enable the trace points you want and also sets probes etc.. 
modprobe amdpgu
# Rescan the bus, the device subsystem will automatically probe amdgpu with this device 
echo 1 > /sys/bus/pci/devices/0000\:00\:02.1/rescan
Apart from that I would really like to see those trace points in TTM instead. I also don't mind adding a dev or pdev pointer to the ttm_bo_device structure for this. 

Regards,
Christian.



Signed-off-by: Tom St Denis <tom.stde...@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu.h        |  1 +
  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 12 ++++++++++++
  drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 11 ++++++++++-
  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c    |  4 ++--
  4 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index d2aaad77c353..2f5781df88c5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -121,6 +121,7 @@ extern int amdgpu_cntl_sb_buf_per_se;
  extern int amdgpu_param_buf_per_se;
  extern int amdgpu_job_hang_limit;
  extern int amdgpu_lbpw;
+extern int amdgpu_enable_map_debugging;
#ifdef CONFIG_DRM_AMDGPU_SI 
  extern int amdgpu_si_support;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 2cdf8443e7d3..0ed777cc2f63 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -120,6 +120,7 @@ int amdgpu_cntl_sb_buf_per_se = 0;
  int amdgpu_param_buf_per_se = 0;
  int amdgpu_job_hang_limit = 0;
  int amdgpu_lbpw = -1;
+int amdgpu_enable_map_debugging = 0;
MODULE_PARM_DESC(vramlimit, "Restrict VRAM for testing, in megabytes"); 
  module_param_named(vramlimit, amdgpu_vram_limit, int, 0600);
@@ -263,6 +264,9 @@ module_param_named(job_hang_limit, amdgpu_job_hang_limit, 
int ,0444);
  MODULE_PARM_DESC(lbpw, "Load Balancing Per Watt (LBPW) support (1 = enable, 0 = 
disable, -1 = auto)");
  module_param_named(lbpw, amdgpu_lbpw, int, 0444);
+MODULE_PARM_DESC(map_debug, "Enable map debugging in kernel (1 = on, 0 = off)"); 
+module_param_named(map_debug, amdgpu_enable_map_debugging, int, 0444);
+
  #ifdef CONFIG_DRM_AMDGPU_SI
#if defined(CONFIG_DRM_RADEON) || defined(CONFIG_DRM_RADEON_MODULE) 
@@ -865,11 +869,19 @@ static struct pci_driver amdgpu_kms_pci_driver = {
  };
+// enable trace events during init 
+static void amdgpu_enable_dma_tracers(void)
+{
+       msleep(3000);
+}
static int __init amdgpu_init(void) 
  {
        int r;
+ if (amdgpu_enable_map_debugging) 
+               amdgpu_enable_dma_tracers();
+
        r = amdgpu_sync_init();
        if (r)
                goto error_sync;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index e7e899190bef..a292e86fbaa7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -37,6 +37,9 @@
  #include "amdgpu.h"
  #include "amdgpu_trace.h"
+void amdgpu_trace_dma_map(struct ttm_tt *ttm); 
+void amdgpu_trace_dma_unmap(struct ttm_tt *ttm);
+
  static void amdgpu_ttm_bo_destroy(struct ttm_buffer_object *tbo)
  {
        struct amdgpu_device *adev = amdgpu_ttm_adev(tbo->bdev);
@@ -625,6 +628,9 @@ int amdgpu_bo_kmap(struct amdgpu_bo *bo, void **ptr)
        if (r)
                return r;
+ if (unlikely(trace_amdgpu_ttm_tt_populate_enabled()) && bo->tbo.mem.mem_type != TTM_PL_VRAM) 
+               amdgpu_trace_dma_map(bo->tbo.ttm);
+
        if (ptr)
                *ptr = amdgpu_bo_kptr(bo);
@@ -640,8 +646,11 @@ void *amdgpu_bo_kptr(struct amdgpu_bo *bo) void amdgpu_bo_kunmap(struct amdgpu_bo *bo) 
  {
-       if (bo->kmap.bo)
+       if (bo->kmap.bo) {
+               if (unlikely(trace_amdgpu_ttm_tt_unpopulate_enabled()) && 
bo->tbo.mem.mem_type != TTM_PL_VRAM)
+                       amdgpu_trace_dma_unmap(bo->tbo.ttm);
                ttm_bo_kunmap(&bo->kmap);
+       }
  }
struct amdgpu_bo *amdgpu_bo_ref(struct amdgpu_bo *bo) 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 26665b4baf36..85727be3fbb7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -663,7 +663,7 @@ int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct 
page **pages)
        return r;
  }
-static void amdgpu_trace_dma_map(struct ttm_tt *ttm) 
+void amdgpu_trace_dma_map(struct ttm_tt *ttm)
  {
        struct amdgpu_device *adev = amdgpu_ttm_adev(ttm->bdev);
        struct amdgpu_ttm_tt *gtt = (void *)ttm;
@@ -679,7 +679,7 @@ static void amdgpu_trace_dma_map(struct ttm_tt *ttm)
        }
  }
-static void amdgpu_trace_dma_unmap(struct ttm_tt *ttm) 
+void amdgpu_trace_dma_unmap(struct ttm_tt *ttm)
  {
        struct amdgpu_device *adev = amdgpu_ttm_adev(ttm->bdev);
        struct amdgpu_ttm_tt *gtt = (void *)ttm;



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