1 /* 2 * Copyright © 2008-2010 Intel Corporation 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining a 5 * copy of this software and associated documentation files (the "Software"), 6 * to deal in the Software without restriction, including without limitation 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 8 * and/or sell copies of the Software, and to permit persons to whom the 9 * Software is furnished to do so, subject to the following conditions: 10 * 11 * The above copyright notice and this permission notice (including the next 12 * paragraph) shall be included in all copies or substantial portions of the 13 * Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 21 * IN THE SOFTWARE. 22 * 23 * Authors: 24 * Eric Anholt <eric@anholt.net> 25 * Chris Wilson <chris@chris-wilson.co.uuk> 26 * 27 */ 28 29 #include "gem/i915_gem_context.h" 30 #include "gt/intel_gt_requests.h" 31 32 #include "i915_drv.h" 33 #include "i915_trace.h" 34 35 I915_SELFTEST_DECLARE(static struct igt_evict_ctl { 36 bool fail_if_busy:1; 37 } igt_evict_ctl;) 38 39 static int ggtt_flush(struct intel_gt *gt) 40 { 41 /* 42 * Not everything in the GGTT is tracked via vma (otherwise we 43 * could evict as required with minimal stalling) so we are forced 44 * to idle the GPU and explicitly retire outstanding requests in 45 * the hopes that we can then remove contexts and the like only 46 * bound by their active reference. 47 */ 48 return intel_gt_wait_for_idle(gt, MAX_SCHEDULE_TIMEOUT); 49 } 50 51 static bool 52 mark_free(struct drm_mm_scan *scan, 53 struct i915_vma *vma, 54 unsigned int flags, 55 struct list_head *unwind) 56 { 57 if (i915_vma_is_pinned(vma)) 58 return false; 59 60 list_add(&vma->evict_link, unwind); 61 return drm_mm_scan_add_block(scan, &vma->node); 62 } 63 64 /** 65 * i915_gem_evict_something - Evict vmas to make room for binding a new one 66 * @vm: address space to evict from 67 * @min_size: size of the desired free space 68 * @alignment: alignment constraint of the desired free space 69 * @color: color for the desired space 70 * @start: start (inclusive) of the range from which to evict objects 71 * @end: end (exclusive) of the range from which to evict objects 72 * @flags: additional flags to control the eviction algorithm 73 * 74 * This function will try to evict vmas until a free space satisfying the 75 * requirements is found. Callers must check first whether any such hole exists 76 * already before calling this function. 77 * 78 * This function is used by the object/vma binding code. 79 * 80 * Since this function is only used to free up virtual address space it only 81 * ignores pinned vmas, and not object where the backing storage itself is 82 * pinned. Hence obj->pages_pin_count does not protect against eviction. 83 * 84 * To clarify: This is for freeing up virtual address space, not for freeing 85 * memory in e.g. the shrinker. 86 */ 87 int 88 i915_gem_evict_something(struct i915_address_space *vm, 89 u64 min_size, u64 alignment, 90 unsigned long color, 91 u64 start, u64 end, 92 unsigned flags) 93 { 94 struct drm_mm_scan scan; 95 struct list_head eviction_list; 96 struct i915_vma *vma, *next; 97 struct drm_mm_node *node; 98 enum drm_mm_insert_mode mode; 99 struct i915_vma *active; 100 int ret; 101 102 lockdep_assert_held(&vm->mutex); 103 trace_i915_gem_evict(vm, min_size, alignment, flags); 104 105 /* 106 * The goal is to evict objects and amalgamate space in rough LRU order. 107 * Since both active and inactive objects reside on the same list, 108 * in a mix of creation and last scanned order, as we process the list 109 * we sort it into inactive/active, which keeps the active portion 110 * in a rough MRU order. 111 * 112 * The retirement sequence is thus: 113 * 1. Inactive objects (already retired, random order) 114 * 2. Active objects (will stall on unbinding, oldest scanned first) 115 */ 116 mode = DRM_MM_INSERT_BEST; 117 if (flags & PIN_HIGH) 118 mode = DRM_MM_INSERT_HIGH; 119 if (flags & PIN_MAPPABLE) 120 mode = DRM_MM_INSERT_LOW; 121 drm_mm_scan_init_with_range(&scan, &vm->mm, 122 min_size, alignment, color, 123 start, end, mode); 124 125 intel_gt_retire_requests(vm->gt); 126 127 search_again: 128 active = NULL; 129 INIT_LIST_HEAD(&eviction_list); 130 list_for_each_entry_safe(vma, next, &vm->bound_list, vm_link) { 131 /* 132 * We keep this list in a rough least-recently scanned order 133 * of active elements (inactive elements are cheap to reap). 134 * New entries are added to the end, and we move anything we 135 * scan to the end. The assumption is that the working set 136 * of applications is either steady state (and thanks to the 137 * userspace bo cache it almost always is) or volatile and 138 * frequently replaced after a frame, which are self-evicting! 139 * Given that assumption, the MRU order of the scan list is 140 * fairly static, and keeping it in least-recently scan order 141 * is suitable. 142 * 143 * To notice when we complete one full cycle, we record the 144 * first active element seen, before moving it to the tail. 145 */ 146 if (i915_vma_is_active(vma)) { 147 if (vma == active) { 148 if (flags & PIN_NONBLOCK) 149 break; 150 151 active = ERR_PTR(-EAGAIN); 152 } 153 154 if (active != ERR_PTR(-EAGAIN)) { 155 if (!active) 156 active = vma; 157 158 list_move_tail(&vma->vm_link, &vm->bound_list); 159 continue; 160 } 161 } 162 163 if (mark_free(&scan, vma, flags, &eviction_list)) 164 goto found; 165 } 166 167 /* Nothing found, clean up and bail out! */ 168 list_for_each_entry_safe(vma, next, &eviction_list, evict_link) { 169 ret = drm_mm_scan_remove_block(&scan, &vma->node); 170 BUG_ON(ret); 171 } 172 173 /* 174 * Can we unpin some objects such as idle hw contents, 175 * or pending flips? But since only the GGTT has global entries 176 * such as scanouts, rinbuffers and contexts, we can skip the 177 * purge when inspecting per-process local address spaces. 178 */ 179 if (!i915_is_ggtt(vm) || flags & PIN_NONBLOCK) 180 return -ENOSPC; 181 182 /* 183 * Not everything in the GGTT is tracked via VMA using 184 * i915_vma_move_to_active(), otherwise we could evict as required 185 * with minimal stalling. Instead we are forced to idle the GPU and 186 * explicitly retire outstanding requests which will then remove 187 * the pinning for active objects such as contexts and ring, 188 * enabling us to evict them on the next iteration. 189 * 190 * To ensure that all user contexts are evictable, we perform 191 * a switch to the perma-pinned kernel context. This all also gives 192 * us a termination condition, when the last retired context is 193 * the kernel's there is no more we can evict. 194 */ 195 if (I915_SELFTEST_ONLY(igt_evict_ctl.fail_if_busy)) 196 return -EBUSY; 197 198 ret = ggtt_flush(vm->gt); 199 if (ret) 200 return ret; 201 202 cond_resched(); 203 204 flags |= PIN_NONBLOCK; 205 goto search_again; 206 207 found: 208 /* drm_mm doesn't allow any other other operations while 209 * scanning, therefore store to-be-evicted objects on a 210 * temporary list and take a reference for all before 211 * calling unbind (which may remove the active reference 212 * of any of our objects, thus corrupting the list). 213 */ 214 list_for_each_entry_safe(vma, next, &eviction_list, evict_link) { 215 if (drm_mm_scan_remove_block(&scan, &vma->node)) 216 __i915_vma_pin(vma); 217 else 218 list_del(&vma->evict_link); 219 } 220 221 /* Unbinding will emit any required flushes */ 222 ret = 0; 223 list_for_each_entry_safe(vma, next, &eviction_list, evict_link) { 224 __i915_vma_unpin(vma); 225 if (ret == 0) 226 ret = __i915_vma_unbind(vma); 227 } 228 229 while (ret == 0 && (node = drm_mm_scan_color_evict(&scan))) { 230 vma = container_of(node, struct i915_vma, node); 231 ret = __i915_vma_unbind(vma); 232 } 233 234 return ret; 235 } 236 237 /** 238 * i915_gem_evict_for_vma - Evict vmas to make room for binding a new one 239 * @vm: address space to evict from 240 * @target: range (and color) to evict for 241 * @flags: additional flags to control the eviction algorithm 242 * 243 * This function will try to evict vmas that overlap the target node. 244 * 245 * To clarify: This is for freeing up virtual address space, not for freeing 246 * memory in e.g. the shrinker. 247 */ 248 int i915_gem_evict_for_node(struct i915_address_space *vm, 249 struct drm_mm_node *target, 250 unsigned int flags) 251 { 252 LIST_HEAD(eviction_list); 253 struct drm_mm_node *node; 254 u64 start = target->start; 255 u64 end = start + target->size; 256 struct i915_vma *vma, *next; 257 int ret = 0; 258 259 lockdep_assert_held(&vm->mutex); 260 GEM_BUG_ON(!IS_ALIGNED(start, I915_GTT_PAGE_SIZE)); 261 GEM_BUG_ON(!IS_ALIGNED(end, I915_GTT_PAGE_SIZE)); 262 263 trace_i915_gem_evict_node(vm, target, flags); 264 265 /* 266 * Retire before we search the active list. Although we have 267 * reasonable accuracy in our retirement lists, we may have 268 * a stray pin (preventing eviction) that can only be resolved by 269 * retiring. 270 */ 271 intel_gt_retire_requests(vm->gt); 272 273 if (i915_vm_has_cache_coloring(vm)) { 274 /* Expand search to cover neighbouring guard pages (or lack!) */ 275 if (start) 276 start -= I915_GTT_PAGE_SIZE; 277 278 /* Always look at the page afterwards to avoid the end-of-GTT */ 279 end += I915_GTT_PAGE_SIZE; 280 } 281 GEM_BUG_ON(start >= end); 282 283 drm_mm_for_each_node_in_range(node, &vm->mm, start, end) { 284 /* If we find any non-objects (!vma), we cannot evict them */ 285 if (node->color == I915_COLOR_UNEVICTABLE) { 286 ret = -ENOSPC; 287 break; 288 } 289 290 GEM_BUG_ON(!drm_mm_node_allocated(node)); 291 vma = container_of(node, typeof(*vma), node); 292 293 /* 294 * If we are using coloring to insert guard pages between 295 * different cache domains within the address space, we have 296 * to check whether the objects on either side of our range 297 * abutt and conflict. If they are in conflict, then we evict 298 * those as well to make room for our guard pages. 299 */ 300 if (i915_vm_has_cache_coloring(vm)) { 301 if (node->start + node->size == target->start) { 302 if (node->color == target->color) 303 continue; 304 } 305 if (node->start == target->start + target->size) { 306 if (node->color == target->color) 307 continue; 308 } 309 } 310 311 if (i915_vma_is_pinned(vma)) { 312 ret = -ENOSPC; 313 break; 314 } 315 316 if (flags & PIN_NONBLOCK && i915_vma_is_active(vma)) { 317 ret = -ENOSPC; 318 break; 319 } 320 321 /* 322 * Never show fear in the face of dragons! 323 * 324 * We cannot directly remove this node from within this 325 * iterator and as with i915_gem_evict_something() we employ 326 * the vma pin_count in order to prevent the action of 327 * unbinding one vma from freeing (by dropping its active 328 * reference) another in our eviction list. 329 */ 330 __i915_vma_pin(vma); 331 list_add(&vma->evict_link, &eviction_list); 332 } 333 334 list_for_each_entry_safe(vma, next, &eviction_list, evict_link) { 335 __i915_vma_unpin(vma); 336 if (ret == 0) 337 ret = __i915_vma_unbind(vma); 338 } 339 340 return ret; 341 } 342 343 /** 344 * i915_gem_evict_vm - Evict all idle vmas from a vm 345 * @vm: Address space to cleanse 346 * 347 * This function evicts all vmas from a vm. 348 * 349 * This is used by the execbuf code as a last-ditch effort to defragment the 350 * address space. 351 * 352 * To clarify: This is for freeing up virtual address space, not for freeing 353 * memory in e.g. the shrinker. 354 */ 355 int i915_gem_evict_vm(struct i915_address_space *vm) 356 { 357 int ret = 0; 358 359 lockdep_assert_held(&vm->mutex); 360 trace_i915_gem_evict_vm(vm); 361 362 /* Switch back to the default context in order to unpin 363 * the existing context objects. However, such objects only 364 * pin themselves inside the global GTT and performing the 365 * switch otherwise is ineffective. 366 */ 367 if (i915_is_ggtt(vm)) { 368 ret = ggtt_flush(vm->gt); 369 if (ret) 370 return ret; 371 } 372 373 do { 374 struct i915_vma *vma, *vn; 375 LIST_HEAD(eviction_list); 376 377 list_for_each_entry(vma, &vm->bound_list, vm_link) { 378 if (i915_vma_is_pinned(vma)) 379 continue; 380 381 __i915_vma_pin(vma); 382 list_add(&vma->evict_link, &eviction_list); 383 } 384 if (list_empty(&eviction_list)) 385 break; 386 387 ret = 0; 388 list_for_each_entry_safe(vma, vn, &eviction_list, evict_link) { 389 __i915_vma_unpin(vma); 390 if (ret == 0) 391 ret = __i915_vma_unbind(vma); 392 if (ret != -EINTR) /* "Get me out of here!" */ 393 ret = 0; 394 } 395 } while (ret == 0); 396 397 return ret; 398 } 399 400 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST) 401 #include "selftests/i915_gem_evict.c" 402 #endif 403