[Intel-gfx] [PATCH 2/4] drm/i915/gtt: Recursive ppgtt clear for gen8
Abdiel Janulgue
abdiel.janulgue at linux.intel.com
Fri Jul 12 15:16:21 UTC 2019
On 12/07/2019 14.27, Chris Wilson wrote:
> With an explicit level, we can refactor the separate clear functions
> as a simple recursive function. The additional knowledge of the level
> allows us to spot when we can free an entire subtree at once.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
Reviewed-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
> drivers/gpu/drm/i915/Kconfig.debug | 15 +++
> drivers/gpu/drm/i915/i915_gem_gtt.c | 154 ++++++++++++++++------------
> 2 files changed, 105 insertions(+), 64 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> index 8d922bb4d953..ed8c787058a5 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -94,6 +94,21 @@ config DRM_I915_TRACE_GEM
>
> If in doubt, say "N".
>
> +config DRM_I915_TRACE_GTT
> + bool "Insert extra ftrace output from the GTT internals"
> + depends on DRM_I915_DEBUG_GEM
> + select TRACING
> + default n
> + help
> + Enable additional and verbose debugging output that will spam
> + ordinary tests, but may be vital for post-mortem debugging when
> + used with /proc/sys/kernel/ftrace_dump_on_oops
> +
> + Recommended for driver developers only.
> +
> + If in doubt, say "N".
> +
> +
> config DRM_I915_SW_FENCE_DEBUG_OBJECTS
> bool "Enable additional driver debugging for fence objects"
> depends on DRM_I915
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 305c65c08a6a..7b2f3188d435 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -46,6 +46,12 @@
>
> #define I915_GFP_ALLOW_FAIL (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN)
>
> +#if IS_ENABLED(CONFIG_DRM_I915_TRACE_GTT)
> +#define DBG(...) trace_printk(__VA_ARGS__)
> +#else
> +#define DBG(...)
> +#endif
> +
> /**
> * DOC: Global GTT views
> *
> @@ -796,6 +802,9 @@ release_pd_entry(struct i915_page_directory * const pd,
> {
> bool free = false;
>
> + if (atomic_add_unless(&pt->used, -1, 1))
> + return false;
> +
> spin_lock(&pd->lock);
> if (atomic_dec_and_test(&pt->used)) {
> clear_pd_entry(pd, idx, scratch);
> @@ -927,86 +936,101 @@ static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
> free_scratch(vm);
> }
>
> -/* Removes entries from a single page table, releasing it if it's empty.
> - * Caller can use the return value to update higher-level entries.
> - */
> -static void gen8_ppgtt_clear_pt(const struct i915_address_space *vm,
> - struct i915_page_table *pt,
> - u64 start, u64 length)
> +static u64 __gen8_ppgtt_clear(struct i915_address_space * const vm,
> + struct i915_page_directory * const pd,
> + u64 start, const u64 end, int lvl)
> {
> - const unsigned int num_entries = gen8_pte_count(start, length);
> - gen8_pte_t *vaddr;
> + const struct i915_page_scratch * const scratch = &vm->scratch[lvl];
> + unsigned int idx, len;
>
> - vaddr = kmap_atomic_px(pt);
> - memset64(vaddr + gen8_pte_index(start),
> - vm->scratch[0].encode,
> - num_entries);
> - kunmap_atomic(vaddr);
> + len = gen8_pd_range(start, end, lvl--, &idx);
> + DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d}\n",
> + __func__, vm, lvl + 1, start, end,
> + idx, len, atomic_read(px_used(pd)));
> + GEM_BUG_ON(!len || len >= atomic_read(px_used(pd)));
>
> - GEM_BUG_ON(num_entries > atomic_read(&pt->used));
> + do {
> + struct i915_page_table *pt = pd->entry[idx];
> +
> + if (atomic_fetch_inc(&pt->used) >> gen8_pd_shift(1) &&
> + gen8_pd_contains(start, end, lvl)) {
> + DBG("%s(%p):{ lvl:%d, idx:%d, start:%llx, end:%llx } removing pd\n",
> + __func__, vm, lvl + 1, idx, start, end);
> + clear_pd_entry(pd, idx, scratch);
> + __gen8_ppgtt_cleanup(vm, as_pd(pt), I915_PDES, lvl);
> + start += (u64)I915_PDES << gen8_pd_shift(lvl);
> + continue;
> + }
>
> - atomic_sub(num_entries, &pt->used);
> -}
> + if (lvl) {
> + start = __gen8_ppgtt_clear(vm, as_pd(pt),
> + start, end, lvl);
> + } else {
> + unsigned int count;
> + u64 *vaddr;
>
> -static void gen8_ppgtt_clear_pd(struct i915_address_space *vm,
> - struct i915_page_directory *pd,
> - u64 start, u64 length)
> -{
> - struct i915_page_table *pt;
> - u32 pde;
> + count = gen8_pt_count(start, end);
> + DBG("%s(%p):{ lvl:%d, start:%llx, end:%llx, idx:%d, len:%d, used:%d} removing pte\n",
> + __func__, vm, lvl, start, end,
> + gen8_pd_index(start, 0), count,
> + atomic_read(&pt->used));
> + GEM_BUG_ON(!count || count >= atomic_read(&pt->used));
>
> - gen8_for_each_pde(pt, pd, start, length, pde) {
> - atomic_inc(&pt->used);
> - gen8_ppgtt_clear_pt(vm, pt, start, length);
> - if (release_pd_entry(pd, pde, pt, &vm->scratch[1]))
> + vaddr = kmap_atomic_px(pt);
> + memset64(vaddr + gen8_pd_index(start, 0),
> + vm->scratch[0].encode,
> + count);
> + kunmap_atomic(vaddr);
> +
> + atomic_sub(count, &pt->used);
> + start += count;
> + }
> +
> + if (release_pd_entry(pd, idx, pt, scratch))
> free_px(vm, pt);
> - }
> + } while (idx++, --len);
> +
> + return start;
> }
>
> -/* Removes entries from a single page dir pointer, releasing it if it's empty.
> - * Caller can use the return value to update higher-level entries
> - */
> -static void gen8_ppgtt_clear_pdp(struct i915_address_space *vm,
> - struct i915_page_directory * const pdp,
> - u64 start, u64 length)
> +static void gen8_ppgtt_clear(struct i915_address_space *vm,
> + u64 start, u64 length)
> {
> - struct i915_page_directory *pd;
> - unsigned int pdpe;
> + GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
> + GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
>
> - gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
> - atomic_inc(px_used(pd));
> - gen8_ppgtt_clear_pd(vm, pd, start, length);
> - if (release_pd_entry(pdp, pdpe, &pd->pt, &vm->scratch[2]))
> - free_px(vm, pd);
> - }
> + start >>= GEN8_PTE_SHIFT;
> + length >>= GEN8_PTE_SHIFT;
> + GEM_BUG_ON(length == 0);
> +
> + __gen8_ppgtt_clear(vm, i915_vm_to_ppgtt(vm)->pd,
> + start, start + length, vm->top);
> }
>
> -static void gen8_ppgtt_clear_3lvl(struct i915_address_space *vm,
> - u64 start, u64 length)
> +static void gen8_ppgtt_clear_pd(struct i915_address_space *vm,
> + struct i915_page_directory *pd,
> + u64 start, u64 length)
> {
> - gen8_ppgtt_clear_pdp(vm, i915_vm_to_ppgtt(vm)->pd, start, length);
> + GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
> + GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
> +
> + start >>= GEN8_PTE_SHIFT;
> + length >>= GEN8_PTE_SHIFT;
> +
> + __gen8_ppgtt_clear(vm, pd, start, start + length, 1);
> }
>
> -/* Removes entries from a single pml4.
> - * This is the top-level structure in 4-level page tables used on gen8+.
> - * Empty entries are always scratch pml4e.
> - */
> -static void gen8_ppgtt_clear_4lvl(struct i915_address_space *vm,
> - u64 start, u64 length)
> +static void gen8_ppgtt_clear_pdp(struct i915_address_space *vm,
> + struct i915_page_directory * const pdp,
> + u64 start, u64 length)
> {
> - struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
> - struct i915_page_directory * const pml4 = ppgtt->pd;
> - struct i915_page_directory *pdp;
> - unsigned int pml4e;
> + GEM_BUG_ON(!IS_ALIGNED(start, BIT_ULL(GEN8_PTE_SHIFT)));
> + GEM_BUG_ON(!IS_ALIGNED(length, BIT_ULL(GEN8_PTE_SHIFT)));
>
> - GEM_BUG_ON(!i915_vm_is_4lvl(vm));
> + start >>= GEN8_PTE_SHIFT;
> + length >>= GEN8_PTE_SHIFT;
>
> - gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
> - atomic_inc(px_used(pdp));
> - gen8_ppgtt_clear_pdp(vm, pdp, start, length);
> - if (release_pd_entry(pml4, pml4e, &pdp->pt, &vm->scratch[3]))
> - free_px(vm, pdp);
> - }
> + __gen8_ppgtt_clear(vm, pdp, start, start + length, 2);
> }
>
> static int gen8_ppgtt_alloc_pd(struct i915_address_space *vm,
> @@ -1171,7 +1195,7 @@ static int gen8_ppgtt_alloc_4lvl(struct i915_address_space *vm,
> if (release_pd_entry(pml4, pml4e, &pdp->pt, &vm->scratch[3]))
> free_px(vm, pdp);
> unwind:
> - gen8_ppgtt_clear_4lvl(vm, from, start - from);
> + gen8_ppgtt_clear(vm, from, start - from);
> out:
> if (alloc)
> free_px(vm, alloc);
> @@ -1484,6 +1508,7 @@ static int gen8_preallocate_top_level_pdp(struct i915_ppgtt *ppgtt)
>
> fill_px(pd, vm->scratch[1].encode);
> set_pd_entry(pdp, pdpe, pd);
> + atomic_inc(px_used(pd)); /* keep pinned */
> }
>
> return 0;
> @@ -1524,6 +1549,7 @@ gen8_alloc_top_pd(struct i915_address_space *vm)
> }
>
> fill_page_dma(px_base(pd), vm->scratch[vm->top].encode, count);
> + atomic_inc(px_used(pd)); /* mark as pinned */
> return pd;
> }
>
> @@ -1573,7 +1599,6 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
> if (i915_vm_is_4lvl(&ppgtt->vm)) {
> ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc_4lvl;
> ppgtt->vm.insert_entries = gen8_ppgtt_insert_4lvl;
> - ppgtt->vm.clear_range = gen8_ppgtt_clear_4lvl;
> } else {
> if (intel_vgpu_active(i915)) {
> err = gen8_preallocate_top_level_pdp(ppgtt);
> @@ -1583,9 +1608,10 @@ static struct i915_ppgtt *gen8_ppgtt_create(struct drm_i915_private *i915)
>
> ppgtt->vm.allocate_va_range = gen8_ppgtt_alloc_3lvl;
> ppgtt->vm.insert_entries = gen8_ppgtt_insert_3lvl;
> - ppgtt->vm.clear_range = gen8_ppgtt_clear_3lvl;
> }
>
> + ppgtt->vm.clear_range = gen8_ppgtt_clear;
> +
> if (intel_vgpu_active(i915))
> gen8_ppgtt_notify_vgt(ppgtt, true);
>
>
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