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Add CacheAllocatorConfig::usePosixShmDirectory() #520

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19 changes: 11 additions & 8 deletions cachelib/allocator/CacheAllocator.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1499,7 +1499,8 @@ class CacheAllocator : public CacheBase {
// and the cache was actually attached.
static bool cleanupStrayShmSegments(const std::string& cacheDir,
bool posix,
const std::string& hugePageMountDir = "");
const std::string& hugePageMountDir = "",
const std::string& posixShmDir = "");

// gives a relative offset to a pointer within the cache.
uint64_t getItemPtrAsOffset(const void* ptr);
Expand Down Expand Up @@ -2949,7 +2950,8 @@ CacheAllocator<CacheTrait>::CacheAllocator(
shmManager_(type != InitMemType::kNone
? std::make_unique<ShmManager>(config_.cacheDir,
config_.isUsingPosixShm(),
config_.hugePageMountDir)
config_.hugePageMountDir,
config_.posixShmDirectory)
: nullptr),
deserializer_(type == InitMemType::kMemAttach ? createDeserializer()
: nullptr),
Expand Down Expand Up @@ -7048,12 +7050,13 @@ template <typename CacheTrait>
bool CacheAllocator<CacheTrait>::cleanupStrayShmSegments(
const std::string& cacheDir,
bool posix,
const std::string& hugePageMountDir) {
const std::string& hugePageMountDir,
const std::string& posixShmDir) {
if (util::getStatIfExists(cacheDir, nullptr) && util::isDir(cacheDir)) {
try {
// cache dir exists. clean up only if there are no other processes
// attached. if another process was attached, the following would fail.
ShmManager::cleanup(cacheDir, posix, hugePageMountDir);
ShmManager::cleanup(cacheDir, posix, hugePageMountDir, posixShmDir);
} catch (const std::exception& e) {
XLOGF(ERR, "Error cleaning up {}. Exception: ", cacheDir, e.what());
return false;
Expand All @@ -7063,13 +7066,13 @@ bool CacheAllocator<CacheTrait>::cleanupStrayShmSegments(
// Any other concurrent process can not be attached to the segments or
// even if it does, we want to mark it for destruction.
ShmManager::removeByName(cacheDir, detail::kShmInfoName, posix,
hugePageMountDir);
hugePageMountDir, posixShmDir);
ShmManager::removeByName(cacheDir, detail::kShmCacheName, posix,
hugePageMountDir);
hugePageMountDir, posixShmDir);
ShmManager::removeByName(cacheDir, detail::kShmHashTableName, posix,
hugePageMountDir);
hugePageMountDir, posixShmDir);
ShmManager::removeByName(cacheDir, detail::kShmChainedItemHashTableName,
posix, hugePageMountDir);
posix, hugePageMountDir, posixShmDir);
}
return true;
}
Expand Down
22 changes: 22 additions & 0 deletions cachelib/allocator/CacheAllocatorConfig.h
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Original file line number Diff line number Diff line change
Expand Up @@ -239,6 +239,13 @@ class CacheAllocatorConfig {
// cachePersistence()
CacheAllocatorConfig& usePosixForShm();

// Like usePosixForShm(), but normal-page segments are files in the given
// directory instead of /dev/shm. Use an existing tmpfs directory. It is not
// saved with the cache: SharedMemAttach with another directory throws.
// @throw std::invalid_argument if the directory is empty or called without
// enabling cachePersistence()
CacheAllocatorConfig& usePosixShmDirectory(std::string directory);

// Requests HugeTLB-backed pages for slab (main cache) memory and access
// container hash tables; persistence metadata stays on normal pages.
// Shorthand for enableSlabHugePages + enableAccessHugePages with the same
Expand Down Expand Up @@ -571,6 +578,9 @@ class CacheAllocatorConfig {
// if true, uses posix shm; if not, uses sys-v (default)
bool usePosixShm{false};

// Directory for normal-page POSIX shm segments; empty means /dev/shm.
std::string posixShmDirectory;

// Huge-page size backing the slab memory segment; default => normal pages.
PageSize slabHugePageSize{};

Expand Down Expand Up @@ -1143,6 +1153,17 @@ CacheAllocatorConfig<T>& CacheAllocatorConfig<T>::usePosixForShm() {
return *this;
}

template <typename T>
CacheAllocatorConfig<T>& CacheAllocatorConfig<T>::usePosixShmDirectory(
std::string directory) {
if (directory.empty()) {
throw std::invalid_argument("usePosixShmDirectory() needs a directory");
}
usePosixForShm();
posixShmDirectory = std::move(directory);
return *this;
}

template <typename T>
void CacheAllocatorConfig<T>::validateHugePageSize(const PageSize& pageSize) {
if (!pageSize.isHugePage()) {
Expand Down Expand Up @@ -1543,6 +1564,7 @@ std::map<std::string, std::string> CacheAllocatorConfig<T>::serialize() const {
configMap["slabHugePageSize"] = pageSizeStr(slabHugePageSize);
configMap["accessHugePageSize"] = pageSizeStr(accessHugePageSize);
configMap["hugePageMountDir"] = hugePageMountDir;
configMap["posixShmDirectory"] = posixShmDirectory;

configMap["defaultAllocSizes"] = "";
// Stringify std::set
Expand Down
7 changes: 5 additions & 2 deletions cachelib/allocator/ReadOnlySharedCacheView.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,17 +48,20 @@ class ReadOnlySharedCacheView {
// address chosen by the kernel
// @param pageSize page size backing the cache's main segment
// @param hugePageMountDir hugetlbfs mount containing a POSIX huge-page cache
// @param posixShmDir the cache's usePosixShmDirectory(), if any
explicit ReadOnlySharedCacheView(const std::string& cacheDir,
bool usePosixShm,
void* addr = nullptr,
const PageSize& pageSize = PageSize(),
const std::string& hugePageMountDir = "")
const std::string& hugePageMountDir = "",
const std::string& posixShmDir = "")
: shm_(ShmManager::attachShmReadOnly(cacheDir,
detail::kShmCacheName,
usePosixShm,
addr,
pageSize,
hugePageMountDir)) {}
hugePageMountDir,
posixShmDir)) {}

// returns the absolute address at which the shared memory mapping is mounted.
// The caller can add a relative offset obtained from
Expand Down
62 changes: 62 additions & 0 deletions cachelib/allocator/tests/CacheAllocatorConfigTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,14 @@
* limitations under the License.
*/

#include <folly/testing/TestUtil.h>

#include <cstring>
#include <filesystem>

#include "cachelib/allocator/CacheAllocatorConfig.h"
#include "cachelib/allocator/MemoryTierCacheConfig.h"
#include "cachelib/allocator/ReadOnlySharedCacheView.h"
#include "cachelib/allocator/memory/Slab.h"
#include "cachelib/allocator/tests/TestBase.h"
#include "cachelib/common/EventSink.h"
Expand Down Expand Up @@ -122,6 +128,62 @@ TEST_F(CacheAllocatorConfigTest, ConflictingHugePageMountDirsThrow) {
EXPECT_EQ("/mnt/hugetlbfs-a", config.hugePageMountDir);
}

TEST_F(CacheAllocatorConfigTest, PosixShmDirectory) {
AllocatorT::Config config;
// Needs cache persistence, as usePosixForShm() does.
EXPECT_THROW(config.usePosixShmDirectory("/segments"), std::invalid_argument);
config.enableCachePersistence("/cache");
EXPECT_THROW(config.usePosixShmDirectory(""), std::invalid_argument);

config.usePosixShmDirectory("/segments");
EXPECT_TRUE(config.isUsingPosixShm());
EXPECT_EQ("/segments", config.posixShmDirectory);
EXPECT_EQ("/segments", config.serialize()["posixShmDirectory"]);
}

TEST_F(CacheAllocatorConfigTest, PosixShmDirectoryWarmRoll) {
folly::test::TemporaryDirectory cacheDir;
folly::test::TemporaryDirectory segmentDir("", "/dev/shm");
const std::string segments = segmentDir.path().string();
const auto makeConfig = [&](const std::string& directory) {
AllocatorT::Config config;
config.setCacheSize(64 * Slab::kSize)
.enableCachePersistence(cacheDir.path().string())
.usePosixShmDirectory(directory);
return config;
};
{
AllocatorT cache(AllocatorT::SharedMemNew, makeConfig(segments));
const auto pool =
cache.addPool("default", cache.getCacheMemoryStats().ramCacheSize);
auto handle = cache.allocate(pool, "key", 100);
ASSERT_NE(nullptr, handle);
std::memset(handle->getMemory(), 'v', 100);
cache.insertOrReplace(handle);
handle.reset();
ASSERT_EQ(AllocatorT::ShutDownStatus::kSuccess, cache.shutDown());
}
ASSERT_FALSE(std::filesystem::is_empty(segments));
{
ReadOnlySharedCacheView view(cacheDir.path().string(), true /* posix */,
nullptr, PageSize(), "", segments);
EXPECT_NE(0u, view.getShmMappingAddress());
}

{
AllocatorT cache(AllocatorT::SharedMemAttach, makeConfig(segments));
auto handle = cache.find("key");
ASSERT_NE(nullptr, handle);
EXPECT_EQ('v', *reinterpret_cast<const char*>(handle->getMemory()));
handle.reset();
ASSERT_EQ(AllocatorT::ShutDownStatus::kSuccess, cache.shutDown());
}

EXPECT_TRUE(AllocatorT::cleanupStrayShmSegments(
cacheDir.path().string(), true /* posix */, "", segments));
EXPECT_TRUE(std::filesystem::is_empty(segments));
}

TEST_F(CacheAllocatorConfigTest, SerializeEvictionPolicyLru) {
LruAllocator::Config config;
auto serialized = config.serialize();
Expand Down
2 changes: 2 additions & 0 deletions cachelib/persistence/PersistenceManager.h
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Expand Up @@ -119,6 +119,8 @@ class PersistenceManager {
CACHELIB_CHECK_THROW(!config.slabHugePageSize.isHugePage() &&
!config.accessHugePageSize.isHugePage(),
"Huge pages are not supported to persist");
CACHELIB_CHECK_THROW(config.posixShmDirectory.empty(),
"usePosixShmDirectory() is not supported to persist");

if (config.nvmConfig.has_value()) {
const auto& navyConfig = config.nvmConfig->navyConfig;
Expand Down
5 changes: 3 additions & 2 deletions cachelib/shm/PosixShmSegment.cpp
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Expand Up @@ -223,11 +223,12 @@ int shmOpenForPageSize(const std::string& name,
int flags,
const PageSize& pageSize,
const std::string& hugePageMountDir) {
if (!pageSize.isHugePage()) {
if (!pageSize.isHugePage() && hugePageMountDir.empty()) {
return detail::shmOpenImpl(name.c_str(), flags);
}
// HugeTLB segments must use a different mount from /dev/shm (which is
// hardcoded by shm_open)
// hardcoded by shm_open). Normal-page segments get a directory only from
// usePosixShmDirectory().
if (hugePageMountDir.empty()) {
util::throwSystemError(
EINVAL,
Expand Down
16 changes: 8 additions & 8 deletions cachelib/shm/PosixShmSegment.h
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Expand Up @@ -49,8 +49,8 @@ class PosixShmSegment : public ShmBase {
//
// @param name Name of the segment
// @param opts the options for attaching to the segment.
// @param hugePageMountDir hugetlbfs mount backing the segment when it uses
// huge pages; empty for normal (tmpfs) segments.
// @param hugePageMountDir directory of the segment: the hugetlbfs mount for
// huge pages; for normal pages "" means /dev/shm.
PosixShmSegment(ShmAttachT,
const std::string& name,
ShmSegmentOpts opts = {},
Expand All @@ -60,8 +60,8 @@ class PosixShmSegment : public ShmBase {
// @param name The name of the segment
// @param size The size of the segment. This will be rounded up to the
// nearest page size.
// @param hugePageMountDir hugetlbfs mount to back the segment on when it
// uses huge pages; empty for normal (tmpfs) segments.
// @param hugePageMountDir directory of the segment: the hugetlbfs mount for
// huge pages; for normal pages "" means /dev/shm.
PosixShmSegment(ShmNewT,
const std::string& name,
size_t size,
Expand Down Expand Up @@ -98,8 +98,8 @@ class PosixShmSegment : public ShmBase {

// useful for removing without attaching
// @param name Name of the segment
// @param hugePageMountDir hugetlbfs mount backing the segment if it uses
// huge pages; empty for normal (tmpfs) segments.
// @param hugePageMountDir directory to remove the segment from in addition
// to /dev/shm, if not empty.
// @return true if the segment existed. false otherwise
static bool removeByName(const std::string& name,
const std::string& hugePageMountDir = "");
Expand All @@ -126,8 +126,8 @@ class PosixShmSegment : public ShmBase {

void memBind(void* addr) const;

// hugetlbfs mount backing this segment when it uses huge pages ("" for
// normal/tmpfs segments). Needed to locate the file for removal.
// Directory of the segment file ("" for /dev/shm). Needed to locate the
// file for removal.
const std::string hugePageMountDir_;

// file descriptor associated with the shm. This has FD_CLOEXEC set
Expand Down
8 changes: 4 additions & 4 deletions cachelib/shm/Shm.h
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Expand Up @@ -47,8 +47,8 @@ class ShmSegment {
// @param name name of the segment
// @param size size of the segment.
// @param opts the options for the segment.
// @param hugePageMountDir hugetlbfs mount for a huge-page POSIX segment;
// ignored for SysV and normal-page segments.
// @param hugePageMountDir directory of a POSIX segment: the hugetlbfs mount
// for huge pages; for normal pages "" means /dev/shm. Unused by SysV.
ShmSegment(ShmNewT,
std::string name,
size_t size,
Expand All @@ -67,8 +67,8 @@ class ShmSegment {
// attach to an existing segment with the given key
// @param name name of the segment
// @param opts the options for the segment.
// @param hugePageMountDir hugetlbfs mount for a huge-page POSIX segment;
// ignored for SysV and normal-page segments.
// @param hugePageMountDir directory of a POSIX segment: the hugetlbfs mount
// for huge pages; for normal pages "" means /dev/shm. Unused by SysV.
ShmSegment(ShmAttachT,
std::string name,
bool usePosix,
Expand Down
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