/*
 * Copyright © 2012-2018 Rob Clark <robclark@freedesktop.org>
 * SPDX-License-Identifier: MIT
 *
 * Authors:
 *    Rob Clark <robclark@freedesktop.org>
 */

#include "freedreno_drmif.h"
#include "freedreno_drm_perfetto.h"
#include "freedreno_priv.h"

#define FD_BO_CACHE_STATS 0

#define BO_CACHE_LOG(cache, fmt, ...) do {                      \
      if (FD_BO_CACHE_STATS) {                                  \
         mesa_logi("%s: "fmt, (cache)->name, ##__VA_ARGS__);    \
      }                                                         \
   } while (0)

static void
bo_remove_from_bucket(struct fd_bo_bucket *bucket, struct fd_bo *bo)
{
   list_delinit(&bo->node);
   bucket->count--;
}

static void
dump_cache_stats(struct fd_bo_cache *cache)
{
   if (!FD_BO_CACHE_STATS)
      return;

   static int cnt;

   if ((++cnt % 32))
      return;

   int size = 0;
   int count = 0;
   int hits = 0;
   int misses = 0;
   int expired = 0;

   for (int i = 0; i < cache->num_buckets; i++) {
      char *state = "";

      struct fd_bo_bucket *bucket = &cache->cache_bucket[i];

      if (bucket->count > 0) {
         struct fd_bo *bo = first_bo(&bucket->list);
         if (fd_bo_state(bo) == FD_BO_STATE_IDLE)
            state = " (idle)";
      }

      BO_CACHE_LOG(cache, "bucket[%u]: count=%d\thits=%d\tmisses=%d\texpired=%d%s",
                   bucket->size, bucket->count, bucket->hits,
                   bucket->misses, bucket->expired, state);

      size += bucket->size * bucket->count;
      count += bucket->count;
      hits += bucket->hits;
      misses += bucket->misses;
      expired += bucket->expired;
   }

   BO_CACHE_LOG(cache, "size=%d\tcount=%d\thits=%d\tmisses=%d\texpired=%d",
                size, count, hits, misses, expired);
}

static void
add_bucket(struct fd_bo_cache *cache, int size)
{
   unsigned int i = cache->num_buckets;
   struct fd_bo_bucket *bucket = &cache->cache_bucket[i];

   assert(i < ARRAY_SIZE(cache->cache_bucket));

   list_inithead(&bucket->list);
   bucket->size = size;
   bucket->count = 0;
   bucket->hits = 0;
   bucket->misses = 0;
   bucket->expired = 0;
   cache->num_buckets++;
}

/**
 * @coarse: if true, only power-of-two bucket sizes, otherwise
 *    fill in for a bit smoother size curve..
 */
void
fd_bo_cache_init(struct fd_bo_cache *cache, int coarse, const char *name)
{
   unsigned long size, cache_max_size = 64 * 1024 * 1024;

   cache->name = name;
   simple_mtx_init(&cache->lock, mtx_plain);

   /* OK, so power of two buckets was too wasteful of memory.
    * Give 3 other sizes between each power of two, to hopefully
    * cover things accurately enough.  (The alternative is
    * probably to just go for exact matching of sizes, and assume
    * that for things like composited window resize the tiled
    * width/height alignment and rounding of sizes to pages will
    * get us useful cache hit rates anyway)
    */
   add_bucket(cache, os_page_size);
   add_bucket(cache, os_page_size * 2);
   if (!coarse)
      add_bucket(cache, os_page_size * 3);

   /* Initialize the linked lists for BO reuse cache. */
   for (size = 4 * os_page_size; size <= cache_max_size; size *= 2) {
      add_bucket(cache, size);
      if (!coarse) {
         add_bucket(cache, size + size * 1 / 4);
         add_bucket(cache, size + size * 2 / 4);
         add_bucket(cache, size + size * 3 / 4);
      }
   }
}

/* Frees older cached buffers.  Called under table_lock */
void
fd_bo_cache_cleanup(struct fd_bo_cache *cache, time_t time)
{
   int i, cnt = 0;

   if (cache->time == time)
      return;

   struct list_head freelist;

   list_inithead(&freelist);

   simple_mtx_lock(&cache->lock);
   for (i = 0; i < cache->num_buckets; i++) {
      struct fd_bo_bucket *bucket = &cache->cache_bucket[i];
      struct fd_bo *bo;

      while (!list_is_empty(&bucket->list)) {
         bo = first_bo(&bucket->list);

         /* keep things in cache for at least 1 second: */
         if (time && ((time - bo->free_time) <= 1))
            break;

         if (cnt == 0) {
            BO_CACHE_LOG(cache, "cache cleanup");
            dump_cache_stats(cache);
         }

         VG_BO_OBTAIN(bo);
         bo_remove_from_bucket(bucket, bo);
         bucket->expired++;
         list_addtail(&bo->node, &freelist);
         fd_alloc_log(bo, FD_ALLOC_CACHE, FD_ALLOC_NONE);

         cnt++;
      }
   }
   simple_mtx_unlock(&cache->lock);

   fd_bo_del_list_nocache(&freelist);

   if (cnt > 0) {
      BO_CACHE_LOG(cache, "cache cleaned %u BOs", cnt);
      dump_cache_stats(cache);
   }

   cache->time = time;
}

static struct fd_bo_bucket *
get_bucket(struct fd_bo_cache *cache, uint32_t size)
{
   int i;

   /* hmm, this is what intel does, but I suppose we could calculate our
    * way to the correct bucket size rather than looping..
    */
   for (i = 0; i < cache->num_buckets; i++) {
      struct fd_bo_bucket *bucket = &cache->cache_bucket[i];
      if (bucket->size >= size) {
         return bucket;
      }
   }

   return NULL;
}

static struct fd_bo *
find_in_bucket(struct fd_bo_bucket *bucket, uint32_t flags)
{
   struct fd_bo *bo = NULL;

   /* TODO .. if we had an ALLOC_FOR_RENDER flag like intel, we could
    * skip the busy check.. if it is only going to be a render target
    * then we probably don't need to stall..
    *
    * NOTE that intel takes ALLOC_FOR_RENDER bo's from the list tail
    * (MRU, since likely to be in GPU cache), rather than head (LRU)..
    */
   foreach_bo (entry, &bucket->list) {
      if (fd_bo_state(entry) != FD_BO_STATE_IDLE) {
         break;
      }
      if (entry->alloc_flags == flags) {
         bo = entry;
         bo_remove_from_bucket(bucket, bo);
         break;
      }
   }

   return bo;
}

/* NOTE: size is potentially rounded up to bucket size: */
struct fd_bo *
fd_bo_cache_alloc(struct fd_bo_cache *cache, uint32_t *size, uint32_t flags)
{
   struct fd_bo *bo = NULL;
   struct fd_bo_bucket *bucket;

   *size = align(*size, os_page_size);
   bucket = get_bucket(cache, *size);

   struct list_head freelist;

   list_inithead(&freelist);

   /* see if we can be green and recycle: */
retry:
   if (bucket) {
      *size = bucket->size;
      simple_mtx_lock(&cache->lock);
      bo = find_in_bucket(bucket, flags);
      simple_mtx_unlock(&cache->lock);
      if (bo) {
         VG_BO_OBTAIN(bo);
         if (bo->funcs->madvise(bo, true) <= 0) {
            /* we've lost the backing pages, delete and try again: */
            list_addtail(&bo->node, &freelist);
            fd_alloc_log(bo, FD_ALLOC_CACHE, FD_ALLOC_NONE);
            goto retry;
         }
         p_atomic_set(&bo->refcnt, 1);
         bo->reloc_flags = FD_RELOC_FLAGS_INIT;
         bucket->hits++;
         fd_alloc_log(bo, FD_ALLOC_CACHE, FD_ALLOC_ACTIVE);
         return bo;
      }
      bucket->misses++;
   }

   fd_bo_del_list_nocache(&freelist);

   BO_CACHE_LOG(cache, "miss on size=%u, flags=0x%x, bucket=%u", *size, flags,
                bucket ? bucket->size : 0);
   dump_cache_stats(cache);

   return NULL;
}

int
fd_bo_cache_free(struct fd_bo_cache *cache, struct fd_bo *bo)
{
   if (bo->alloc_flags & (FD_BO_SHARED | _FD_BO_NOSYNC))
      return -1;

   struct fd_bo_bucket *bucket = get_bucket(cache, bo->size);

   /* see if we can be green and recycle: */
   if (bucket) {
      struct timespec time;

      bo->funcs->madvise(bo, false);

      clock_gettime(CLOCK_MONOTONIC, &time);

      bo->free_time = time.tv_sec;
      VG_BO_RELEASE(bo);

      simple_mtx_lock(&cache->lock);
      list_addtail(&bo->node, &bucket->list);
      bucket->count++;
      simple_mtx_unlock(&cache->lock);

      fd_alloc_log(bo, FD_ALLOC_ACTIVE, FD_ALLOC_CACHE);
      fd_bo_cache_cleanup(cache, time.tv_sec);

      return 0;
   }

   return -1;
}