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Fix thread contention in Cache #145

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merged 1 commit into from
Nov 30, 2021
Merged

Fix thread contention in Cache #145

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21 changes: 20 additions & 1 deletion cpp/include/cucim/cache/image_cache_config.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,26 @@ constexpr uint64_t kOneMiB = 1024UL * 1024;
constexpr std::string_view kDefaultCacheTypeStr = "nocache";
constexpr CacheType kDefaultCacheType = cucim::cache::CacheType::kNoCache;
constexpr uint64_t kDefaultCacheMemoryCapacity = 1024UL;
constexpr uint32_t kDefaultCacheMutexPoolCapacity = 11117;
/**
* @brief Mutex Pool size
*
* >>> from functools import reduce
* >>> def calc(pool_size, thread_size):
* >>> a = reduce(lambda x,y: x*y, range(pool_size, pool_size - thread_size, -1))
* >>> print(1 - (a / (pool_size**thread_size)))
*
* >>> calc(100003, 128)
* 0.07809410393222294
* >>> calc(100003, 256)
* 0.2786772006302005
*
* See https://godbolt.org/z/Tvx8179xK
* Creating a pool of 100000 mutexes takes only about 4 MB which is not big.
* I believe that making the mutex size biggger enough helps to the reduce the thread contention.
* For systems with more than 256 threads, the pool size should be larger.
* Choose a prime number for the pool size (https://primes.utm.edu/lists/small/100000.txt).
*/
constexpr uint32_t kDefaultCacheMutexPoolCapacity = 100003;
constexpr uint32_t kDefaultCacheListPadding = 10000;
constexpr uint32_t kDefaultCacheExtraSharedMemorySize = 100;
constexpr bool kDefaultCacheRecordStat = false;
Expand Down
16 changes: 10 additions & 6 deletions cpp/plugins/cucim.kit.cuslide/src/cuslide/tiff/ifd.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -501,6 +501,8 @@ bool IFD::read_region_tiles(const TIFF* tiff,
uint32_t dest_pixel_index_x = 0;

uint32_t index = index_y + offset_sx;
// Calculate a simple hash value for the tile index
uint64_t index_hash = ifd_hash_value ^ (static_cast<uint64_t>(index) | (static_cast<uint64_t>(index) << 32));
for (uint32_t offset_x = offset_sx; offset_x <= offset_ex; ++offset_x, ++index)
{
auto tiledata_offset = static_cast<uint64_t>(ifd->image_piece_offsets_[index]);
Expand All @@ -519,11 +521,11 @@ bool IFD::read_region_tiles(const TIFF* tiff,
if (tiledata_size > 0)
{
auto key = image_cache.create_key(ifd_hash_value, index);
image_cache.lock(index);
image_cache.lock(index_hash);
auto value = image_cache.find(key);
if (value)
{
image_cache.unlock(index);
image_cache.unlock(index_hash);
tile_data = static_cast<uint8_t*>(value->data);
}
else
Expand Down Expand Up @@ -577,7 +579,7 @@ bool IFD::read_region_tiles(const TIFF* tiff,

value = image_cache.create_value(tile_data, tile_raster_nbytes);
image_cache.insert(key, value);
image_cache.unlock(index);
image_cache.unlock(index_hash);
}

for (uint32_t ty = tile_pixel_offset_sy; ty <= tile_pixel_offset_ey;
Expand Down Expand Up @@ -743,6 +745,8 @@ bool IFD::read_region_tiles_boundary(const TIFF* tiff,
uint32_t dest_pixel_index_x = 0;

int64_t index = index_y + offset_sx;
// Calculate a simple hash value for the tile index
uint64_t index_hash = ifd_hash_value ^ (static_cast<uint64_t>(index) | (static_cast<uint64_t>(index) << 32));
for (int64_t offset_x = offset_sx; offset_x <= offset_ex; ++offset_x, ++index)
{
uint64_t tiledata_offset = 0;
Expand Down Expand Up @@ -798,11 +802,11 @@ bool IFD::read_region_tiles_boundary(const TIFF* tiff,
uint8_t* tile_data = tile_raster;

auto key = image_cache.create_key(ifd_hash_value, index);
image_cache.lock(index);
image_cache.lock(index_hash);
auto value = image_cache.find(key);
if (value)
{
image_cache.unlock(index);
image_cache.unlock(index_hash);
tile_data = static_cast<uint8_t*>(value->data);
}
else
Expand Down Expand Up @@ -855,7 +859,7 @@ bool IFD::read_region_tiles_boundary(const TIFF* tiff,
}
value = image_cache.create_value(tile_data, tile_raster_nbytes);
image_cache.insert(key, value);
image_cache.unlock(index);
image_cache.unlock(index_hash);
}
if (copy_partial)
{
Expand Down