[Public]
> -----Original Message-----
> From: Lazar, Lijo <Lijo.Lazar@xxxxxxx>
> Sent: Thursday, February 13, 2025 1:35 AM
> To: Kim, Jonathan <Jonathan.Kim@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH] drm/amdgpu: simplify xgmi peer info calls
>
>
>
> On 2/12/2025 9:27 PM, Jonathan Kim wrote:
> > Deprecate KFD XGMI peer info calls in favour of calling directly from
> > simplified XGMI peer info functions.
> >
> > Signed-off-by: Jonathan Kim <jonathan.kim@xxxxxxx>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 42 ------------------
> > drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 5 ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c | 51 +++++++++++++++++-----
> > drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h | 6 +--
> > drivers/gpu/drm/amd/amdkfd/kfd_crat.c | 11 +++--
> > 5 files changed, 48 insertions(+), 67 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > index 0312231b703e..4cec3a873995 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
> > @@ -555,48 +555,6 @@ int amdgpu_amdkfd_get_dmabuf_info(struct
> amdgpu_device *adev, int dma_buf_fd,
> > return r;
> > }
> >
> > -uint8_t amdgpu_amdkfd_get_xgmi_hops_count(struct amdgpu_device *dst,
> > - struct amdgpu_device *src)
> > -{
> > - struct amdgpu_device *peer_adev = src;
> > - struct amdgpu_device *adev = dst;
> > - int ret = amdgpu_xgmi_get_hops_count(adev, peer_adev);
> > -
> > - if (ret < 0) {
> > - DRM_ERROR("amdgpu: failed to get xgmi hops count between
> node %d and %d. ret = %d\n",
> > - adev->gmc.xgmi.physical_node_id,
> > - peer_adev->gmc.xgmi.physical_node_id, ret);
> > - ret = 0;
> > - }
> > - return (uint8_t)ret;
> > -}
> > -
> > -int amdgpu_amdkfd_get_xgmi_bandwidth_mbytes(struct amdgpu_device *dst,
> > - struct amdgpu_device *src,
> > - bool is_min)
> > -{
> > - struct amdgpu_device *adev = dst, *peer_adev;
> > - int num_links;
> > -
> > - if (amdgpu_ip_version(adev, GC_HWIP, 0) < IP_VERSION(9, 4, 2))
> > - return 0;
> > -
> > - if (src)
> > - peer_adev = src;
> > -
> > - /* num links returns 0 for indirect peers since indirect route is unknown. */
> > - num_links = is_min ? 1 : amdgpu_xgmi_get_num_links(adev, peer_adev);
> > - if (num_links < 0) {
> > - DRM_ERROR("amdgpu: failed to get xgmi num links between
> node %d and %d. ret = %d\n",
> > - adev->gmc.xgmi.physical_node_id,
> > - peer_adev->gmc.xgmi.physical_node_id, num_links);
> > - num_links = 0;
> > - }
> > -
> > - /* Aldebaran xGMI DPM is defeatured so assume x16 x 25Gbps for
> bandwidth. */
> > - return (num_links * 16 * 25000)/BITS_PER_BYTE;
> > -}
> > -
> > int amdgpu_amdkfd_get_pcie_bandwidth_mbytes(struct amdgpu_device *adev,
> bool is_min)
> > {
> > int num_lanes_shift = (is_min ? ffs(adev->pm.pcie_mlw_mask) :
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > index 092dbd8bec97..28eb1cd0eb5a 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
> > @@ -255,11 +255,6 @@ int amdgpu_amdkfd_get_dmabuf_info(struct
> amdgpu_device *adev, int dma_buf_fd,
> > uint64_t *bo_size, void *metadata_buffer,
> > size_t buffer_size, uint32_t *metadata_size,
> > uint32_t *flags, int8_t *xcp_id);
> > -uint8_t amdgpu_amdkfd_get_xgmi_hops_count(struct amdgpu_device *dst,
> > - struct amdgpu_device *src);
> > -int amdgpu_amdkfd_get_xgmi_bandwidth_mbytes(struct amdgpu_device *dst,
> > - struct amdgpu_device *src,
> > - bool is_min);
> > int amdgpu_amdkfd_get_pcie_bandwidth_mbytes(struct amdgpu_device *adev,
> bool is_min);
> > int amdgpu_amdkfd_send_close_event_drain_irq(struct amdgpu_device *adev,
> > uint32_t *payload);
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> > index 74b4349e345a..d18d2a26cc91 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> > @@ -818,28 +818,59 @@ int amdgpu_xgmi_update_topology(struct
> amdgpu_hive_info *hive, struct amdgpu_dev
> > * num_hops[2:0] = number of hops
> > */
> > int amdgpu_xgmi_get_hops_count(struct amdgpu_device *adev,
> > - struct amdgpu_device *peer_adev)
> > + struct amdgpu_device *peer_adev)
> > {
> > struct psp_xgmi_topology_info *top = &adev->psp.xgmi_context.top_info;
> > uint8_t num_hops_mask = 0x7;
> > int i;
> >
> > + if (!adev->gmc.xgmi.supported)
> > + return 0;
> > +
> > for (i = 0 ; i < top->num_nodes; ++i)
> > if (top->nodes[i].node_id == peer_adev->gmc.xgmi.node_id)
> > return top->nodes[i].num_hops & num_hops_mask;
> > - return -EINVAL;
> > +
> > + DRM_ERROR("amdgpu: failed to get xgmi hops count between node %d
> and %d.\n",
>
> Suggest to use dev_ function to identify the device pci number. Since
> the function still passes, maybe info level is good enough.
Ack'd. Will change.
>
> > + adev->gmc.xgmi.physical_node_id,
> > + peer_adev->gmc.xgmi.physical_node_id);
> > +
> > + return 0;
> > }
> >
> > -int amdgpu_xgmi_get_num_links(struct amdgpu_device *adev,
> > - struct amdgpu_device *peer_adev)
> > +int amdgpu_xgmi_get_bandwidth_mbytes(struct amdgpu_device *adev,
> > + struct amdgpu_device *peer_adev)
> > {
> > - struct psp_xgmi_topology_info *top = &adev->psp.xgmi_context.top_info;
> > - int i;
> > + int num_links = !peer_adev ? 1 : 0;
> >
> > - for (i = 0 ; i < top->num_nodes; ++i)
> > - if (top->nodes[i].node_id == peer_adev->gmc.xgmi.node_id)
> > - return top->nodes[i].num_links;
> > - return -EINVAL;
> > + if (!adev->gmc.xgmi.supported)
> > + return 0;
> > +
> > + if (peer_adev) {
> > + struct psp_xgmi_topology_info *top = &adev-
> >psp.xgmi_context.top_info;
> > + int i;
> > +
> > + for (i = 0 ; i < top->num_nodes; ++i) {
> > + if (top->nodes[i].node_id != peer_adev->gmc.xgmi.node_id)
> > + continue;
> > +
> > + num_links = top->nodes[i].num_links;
> > + break;
> > + }
> > + }
> > +
> > + /* num links returns 0 for indirect peers since indirect route is unknown. */
> > + if (!num_links) {
>
> This looks problematic. I guess, it is better to keep the old way of
> passing min/max. Otherwise, there is a chance that min reports some
> value and max could report this error.
I don't think this is a problem. The old way of passing is_min == true is tied to peer_dev == NULL, which made it a redundant argument.
is_min == false doesn't prevent the issue you've mentioned from happening because the old code effective sets num_link = 0 if the peer_dev search fails anyways.
With the line at the top of the proposed function:
> > + int num_links = !peer_adev ? 1 : 0;
The sematics are as follows:
- NULL peer_dev indicates that caller doesn't want peer-to-peer data to factor num_links into bandwidth reporting so assume a single XGMI link in bandwidth calculation.
- If a failed peer_dev search ends up with num_links == 0, that means the caller passed in an invalid node (i.e. it's not one of the nodes that's been registered to the hive).
Currently, get_hops_count (old and proposed) operates in the same fashion too.
So the functionality between the proposed changes and old changes should have remained the same.
I'm open to adjusting get_num_hops & get_bandwidth_mbytes to return either -ENODEV (device not found in hive) or -EINVAL (bad peer_dev request) on a failed search.
That would require a change to KFD CRAT logic to error return itself on an error.
However, this would change the behaviour of a bandwidth reporting error where ROCm could still function, to the KFD not loading at all.
Currently, the consequence of passing an incorrect peer_dev to the bandwidth call would result in the ROCm Runtime not issuing an SDMA ganged copy i.e. potential peer-to-peer performance drop.
Jon
>
> Thanks,
> Lijo
>
> > + DRM_ERROR("amdgpu: failed to get xgmi num links between
> node %d and %d.\n",
> > + adev->gmc.xgmi.physical_node_id,
> > + peer_adev->gmc.xgmi.physical_node_id);
> > + }
> > +
> > + /*
> > + * TBD - will update IP based bandwidth later.
> > + * Bandwidth currently assumed to be x16 lanes x 25Gbps.
> > + */
> > + return (num_links * 16 * 25000)/BITS_PER_BYTE;
> > }
> >
> > bool amdgpu_xgmi_get_is_sharing_enabled(struct amdgpu_device *adev,
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> > index d1282b4c6348..325e7972469d 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> > @@ -62,10 +62,8 @@ int amdgpu_xgmi_update_topology(struct
> amdgpu_hive_info *hive, struct amdgpu_dev
> > int amdgpu_xgmi_add_device(struct amdgpu_device *adev);
> > int amdgpu_xgmi_remove_device(struct amdgpu_device *adev);
> > int amdgpu_xgmi_set_pstate(struct amdgpu_device *adev, int pstate);
> > -int amdgpu_xgmi_get_hops_count(struct amdgpu_device *adev,
> > - struct amdgpu_device *peer_adev);
> > -int amdgpu_xgmi_get_num_links(struct amdgpu_device *adev,
> > - struct amdgpu_device *peer_adev);
> > +int amdgpu_xgmi_get_hops_count(struct amdgpu_device *adev, struct
> amdgpu_device *peer_adev);
> > +int amdgpu_xgmi_get_bandwidth_mbytes(struct amdgpu_device *adev, struct
> amdgpu_device *peer_adev);
> > bool amdgpu_xgmi_get_is_sharing_enabled(struct amdgpu_device *adev,
> > struct amdgpu_device *peer_adev);
> > uint64_t amdgpu_xgmi_get_relative_phy_addr(struct amdgpu_device *adev,
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> > index 70b3ae0b74fe..a787d192390c 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
> > @@ -2133,8 +2133,8 @@ static int kfd_fill_gpu_direct_io_link_to_cpu(int
> *avail_size,
> > bool ext_cpu = KFD_GC_VERSION(kdev) != IP_VERSION(9, 4, 3);
> > int mem_bw = 819200, weight = ext_cpu ?
> KFD_CRAT_XGMI_WEIGHT :
> >
> KFD_CRAT_INTRA_SOCKET_WEIGHT;
> > - uint32_t bandwidth = ext_cpu ?
> amdgpu_amdkfd_get_xgmi_bandwidth_mbytes(
> > - kdev->adev, NULL, true) :
> mem_bw;
> > + uint32_t bandwidth = ext_cpu ?
> amdgpu_xgmi_get_bandwidth_mbytes(kdev->adev, NULL) :
> > + mem_bw;
> >
> > /*
> > * with host gpu xgmi link, host can access gpu memory whether
> > @@ -2198,12 +2198,11 @@ static int kfd_fill_gpu_xgmi_link_to_gpu(int
> *avail_size,
> >
> > if (use_ta_info) {
> > sub_type_hdr->weight_xgmi = KFD_CRAT_XGMI_WEIGHT *
> > - amdgpu_amdkfd_get_xgmi_hops_count(kdev->adev,
> peer_kdev->adev);
> > + amdgpu_xgmi_get_hops_count(kdev->adev, peer_kdev-
> >adev);
> > sub_type_hdr->maximum_bandwidth_mbs =
> > - amdgpu_amdkfd_get_xgmi_bandwidth_mbytes(kdev->adev,
> > - peer_kdev->adev, false);
> > + amdgpu_xgmi_get_bandwidth_mbytes(kdev->adev,
> peer_kdev->adev);
> > sub_type_hdr->minimum_bandwidth_mbs = sub_type_hdr-
> >maximum_bandwidth_mbs ?
> > - amdgpu_amdkfd_get_xgmi_bandwidth_mbytes(kdev->adev,
> NULL, true) : 0;
> > + amdgpu_xgmi_get_bandwidth_mbytes(kdev->adev, NULL) :
> 0;
> > } else {
> > bool is_single_hop = kdev->kfd == peer_kdev->kfd;
> > int weight = is_single_hop ?
> KFD_CRAT_INTRA_SOCKET_WEIGHT :
