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[AMD Official Use Only - AMD Internal Distribution Only]
The change of granularity from 0x3F to 0x1B is based on review comments from Felix
From: Yang, Philip <Philip.Yang@xxxxxxx>
Sent: Tuesday, September 3, 2024 11:36 AM
To: Chen, Xiaogang <Xiaogang.Chen@xxxxxxx>; Errabolu, Ramesh <Ramesh.Errabolu@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH V3] drm/amdgpu: Surface svm_default_granularity, a RW module parameter
On 2024-08-29 18:31, Chen, Xiaogang wrote:
On 8/29/2024 5:13 PM, Ramesh Errabolu wrote:
Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
Enables users to update SVM's default granularity, used in
buffer migration and handling of recoverable page faults.
Param value is set in terms of log(numPages(buffer)),
e.g. 9 for a 2 MIB buffer
Forgot asking if this parameter is request from customer or used for debug/experiment purpose? If it is later, how about put it at debug fs? There are already many driver parameters.
debugfs is not always available, depending on kernel configuration, and debugfs seems for debugging purpose, ex. /sys/kernel/debug/kfd/mqds, hqds, not for functional purpose. one comment embedded below.
Regards
Xiaogang
Signed-off-by: Ramesh Errabolu
<Ramesh.Errabolu@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu.h | 1 +
drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 17 +++++++++++++++++
drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 6 ++++++
drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 25 +++++++++++++++----------
4 files changed, 39 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index e8c284aea1f2..8eb934af02f2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -237,6 +237,7 @@ extern int sched_policy;
extern bool debug_evictions;
extern bool no_system_mem_limit;
extern int halt_if_hws_hang;
+extern uint amdgpu_svm_default_granularity;
#else
static const int __maybe_unused sched_policy = KFD_SCHED_POLICY_HWS;
static const bool __maybe_unused debug_evictions; /* = false */
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index b9529948f2b2..442039436cb3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -169,6 +169,16 @@ uint amdgpu_sdma_phase_quantum = 32;
char *amdgpu_disable_cu;
char *amdgpu_virtual_display;
bool enforce_isolation;
+
+/* Specifies the default granularity for SVM, used in buffer
+ * migration and restoration of backing memory when handling
+ * recoverable page faults.
+ *
+ * The value is given as log(numPages(buffer)); for a 2 MiB
+ * buffer it computes to be 9
+ */
+uint amdgpu_svm_default_granularity = 9;
+
/*
* OverDrive(bit 14) disabled by default
* GFX DCS(bit 19) disabled by default
@@ -320,6 +330,13 @@ module_param_named(pcie_gen2, amdgpu_pcie_gen2, int, 0444);
MODULE_PARM_DESC(msi, "MSI support (1 = enable, 0 = disable, -1 = auto)");
module_param_named(msi, amdgpu_msi, int, 0444);
+/**
+ * DOC: svm_default_granularity (uint)
+ * Used in buffer migration and handling of recoverable page faults
+ */
+MODULE_PARM_DESC(svm_default_granularity, "SVM's default granularity in log(2^Pages), default 9 = 2^9 = 2 MiB");
+module_param_named(svm_default_granularity, amdgpu_svm_default_granularity, uint, 0644);
+
/**
* DOC: lockup_timeout (string)
* Set GPU scheduler timeout value in ms.
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index 9ae9abc6eb43..d6530febabad 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -868,6 +868,12 @@ struct svm_range_list {
struct task_struct *faulting_task;
/* check point ts decides if page fault recovery need be dropped */
uint64_t checkpoint_ts[MAX_GPU_INSTANCE];
+
+ /* Default granularity to use in buffer migration
+ * and restoration of backing memory while handling
+ * recoverable page faults
+ */
+ uint8_t default_granularity;
};
/* Process data */
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index b44dec90969f..624bfe317c9c 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -309,12 +309,13 @@ static void svm_range_free(struct svm_range *prange, bool do_unmap)
}
static void
-svm_range_set_default_attributes(int32_t *location, int32_t *prefetch_loc,
- uint8_t *granularity, uint32_t *flags)
+svm_range_set_default_attributes(struct svm_range_list *svms,
+ int32_t *location, uint8_t *granularity,
+ int32_t *prefetch_loc, uint32_t *flags)
{
*location = KFD_IOCTL_SVM_LOCATION_UNDEFINED;
*prefetch_loc = KFD_IOCTL_SVM_LOCATION_UNDEFINED;
- *granularity = 9;
+ *granularity = svms->default_granularity;
*flags =
KFD_IOCTL_SVM_FLAG_HOST_ACCESS | KFD_IOCTL_SVM_FLAG_COHERENT;
}
@@ -358,9 +359,8 @@ svm_range *svm_range_new(struct svm_range_list *svms, uint64_t start,
bitmap_copy(prange->bitmap_access, svms->bitmap_supported,
MAX_GPU_INSTANCE);
- svm_range_set_default_attributes(&prange->preferred_loc,
- &prange->prefetch_loc,
- &prange->granularity, &prange->flags);
+ svm_range_set_default_attributes(svms, &prange->preferred_loc,
+ &prange->granularity, &prange->prefetch_loc, &prange->flags);
pr_debug("svms 0x%p [0x%llx 0x%llx]\n", svms, start, last);
@@ -2694,9 +2694,10 @@ svm_range_get_range_boundaries(struct kfd_process *p, int64_t addr,
*is_heap_stack = vma_is_initial_heap(vma) || vma_is_initial_stack(vma);
start_limit = max(vma->vm_start >> PAGE_SHIFT,
- (unsigned long)ALIGN_DOWN(addr, 2UL << 8));
+ (unsigned long)ALIGN_DOWN(addr, 1UL << p->svms.default_granularity));
end_limit = min(vma->vm_end >> PAGE_SHIFT,
- (unsigned long)ALIGN(addr + 1, 2UL << 8));
+ (unsigned long)ALIGN(addr + 1, 1UL << p->svms.default_granularity));
+
/* First range that starts after the fault address */
node = interval_tree_iter_first(&p->svms.objects, addr + 1, ULONG_MAX);
if (node) {
@@ -3240,6 +3241,10 @@ int svm_range_list_init(struct kfd_process *p)
if (KFD_IS_SVM_API_SUPPORTED(p->pdds[i]->dev->adev))
bitmap_set(svms->bitmap_supported, i, 1);
+ /* Update default granularity to one bound by user/driver */
+ svms->default_granularity = min_t(u8, amdgpu_svm_default_granularity, 0x1B);
the max granularity is 0x3F, 63 bits, why do you limit max granularity to 0x1B?
Regards,
Philip
+ pr_debug("Default SVM Granularity to use: %d\n", svms->default_granularity);
+
return 0;
}
@@ -3767,8 +3772,8 @@ svm_range_get_attr(struct kfd_process *p, struct mm_struct *mm,
node = interval_tree_iter_first(&svms->objects, start, last);
if (!node) {
pr_debug("range attrs not found return default values\n");
- svm_range_set_default_attributes(&location, &prefetch_loc,
- &granularity, &flags_and);
+ svm_range_set_default_attributes(svms, &location,
+ &granularity, &prefetch_loc, &flags_and);
flags_or = flags_and;
if (p->xnack_enabled)
bitmap_copy(bitmap_access, svms->bitmap_supported,
--
2.34.1
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