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Implement shmem msg zero-copy

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This commit is contained in:
Alexey Rybalchenko
2021-07-14 10:46:12 +02:00
committed by Dennis Klein
parent c57410b820
commit bce380d871
7 changed files with 333 additions and 100 deletions
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99
fairmq/shmem/Manager.h
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@@ -52,29 +52,77 @@
#include <unistd.h> // getuid
#include <sys/types.h> // getuid
#include <sys/mman.h> // mlock
namespace fair::mq::shmem
{
struct ShmPtr
// ShmHeader stores user buffer alignment and the reference count in the following structure:
// [HdrOffset(uint16_t)][Hdr alignment][Hdr][user buffer alignment][user buffer]
// The alignment of Hdr depends on the alignment of std::atomic and is stored in the first entry
struct ShmHeader
{
explicit ShmPtr(char* rPtr)
: realPtr(rPtr)
{}
char* RealPtr()
struct Hdr
{
return realPtr;
uint16_t userOffset;
std::atomic<uint16_t> refCount;
};
static Hdr* HdrPtr(char* ptr)
{
// [HdrOffset(uint16_t)][Hdr alignment][Hdr][user buffer alignment][user buffer]
// ^
return reinterpret_cast<Hdr*>(ptr + sizeof(uint16_t) + *(reinterpret_cast<uint16_t*>(ptr)));
}
char* UserPtr()
static uint16_t HdrPartSize() // [HdrOffset(uint16_t)][Hdr alignment][Hdr]
{
return realPtr + sizeof(uint16_t) + *(reinterpret_cast<uint16_t*>(realPtr));
// [HdrOffset(uint16_t)][Hdr alignment][Hdr][user buffer alignment][user buffer]
// <--------------------------------------->
return sizeof(uint16_t) + alignof(Hdr) + sizeof(Hdr);
}
char* realPtr;
static std::atomic<uint16_t>& RefCountPtr(char* ptr)
{
// get the ref count ptr from the Hdr
return HdrPtr(ptr)->refCount;
}
static char* UserPtr(char* ptr)
{
// [HdrOffset(uint16_t)][Hdr alignment][Hdr][user buffer alignment][user buffer]
// ^
return ptr + HdrPartSize() + HdrPtr(ptr)->userOffset;
}
static uint16_t RefCount(char* ptr) { return RefCountPtr(ptr).load(); }
static uint16_t IncrementRefCount(char* ptr) { return RefCountPtr(ptr).fetch_add(1); }
static uint16_t DecrementRefCount(char* ptr) { return RefCountPtr(ptr).fetch_sub(1); }
static size_t FullSize(size_t size, size_t alignment)
{
// [HdrOffset(uint16_t)][Hdr alignment][Hdr][user buffer alignment][user buffer]
// <--------------------------------------------------------------------------->
return HdrPartSize() + alignment + size;
}
static void Construct(char* ptr, size_t alignment)
{
// place the Hdr in the aligned location, fill it and store its offset to HdrOffset
// the address alignment should be at least 2
assert(reinterpret_cast<uintptr_t>(ptr) % 2 == 0);
// offset to the beginning of the Hdr. store it in the beginning
uint16_t hdrOffset = alignof(Hdr) - ((reinterpret_cast<uintptr_t>(ptr) + sizeof(uint16_t)) % alignof(Hdr));
memcpy(ptr, &hdrOffset, sizeof(hdrOffset));
// offset to the beginning of the user buffer, store in Hdr together with the ref count
uint16_t userOffset = alignment - ((reinterpret_cast<uintptr_t>(ptr) + HdrPartSize()) % alignment);
new(ptr + sizeof(uint16_t) + hdrOffset) Hdr{ userOffset, std::atomic<uint16_t>(1) };
}
static void Destruct(char* ptr) { RefCountPtr(ptr).~atomic(); }
};
class Manager
@@ -635,44 +683,35 @@ class Manager
{
return boost::apply_visitor(SegmentHandleFromAddress(ptr), fSegments.at(segmentId));
}
void* GetAddressFromHandle(const boost::interprocess::managed_shared_memory::handle_t handle, uint16_t segmentId) const
char* GetAddressFromHandle(const boost::interprocess::managed_shared_memory::handle_t handle, uint16_t segmentId) const
{
return boost::apply_visitor(SegmentAddressFromHandle(handle), fSegments.at(segmentId));
}
ShmPtr Allocate(size_t size, size_t alignment = 0)
char* Allocate(size_t size, size_t alignment = 0)
{
alignment = std::max(alignment, alignof(std::max_align_t));
char* ptr = nullptr;
// [offset(uint16_t)][alignment][buffer]
size_t fullSize = sizeof(uint16_t) + alignment + size;
// tools::RateLimiter rateLimiter(20);
size_t fullSize = ShmHeader::FullSize(size, alignment);
while (ptr == nullptr) {
try {
// boost::interprocess::managed_shared_memory::size_type actualSize = size;
// char* hint = 0; // unused for boost::interprocess::allocate_new
// ptr = fSegments.at(fSegmentId).allocation_command<char>(boost::interprocess::allocate_new, size, actualSize, hint);
size_t segmentSize = boost::apply_visitor(SegmentSize(), fSegments.at(fSegmentId));
if (fullSize > segmentSize) {
throw MessageBadAlloc(tools::ToString("Requested message size (", fullSize, ") exceeds segment size (", segmentSize, ")"));
}
ptr = reinterpret_cast<char*>(boost::apply_visitor(SegmentAllocate{fullSize}, fSegments.at(fSegmentId)));
assert(reinterpret_cast<uintptr_t>(ptr) % 2 == 0);
uint16_t offset = 0;
offset = alignment - ((reinterpret_cast<uintptr_t>(ptr) + sizeof(uint16_t)) % alignment);
std::memcpy(ptr, &offset, sizeof(offset));
ptr = boost::apply_visitor(SegmentAllocate{fullSize}, fSegments.at(fSegmentId));
ShmHeader::Construct(ptr, alignment);
} catch (boost::interprocess::bad_alloc& ba) {
// LOG(warn) << "Shared memory full...";
if (ThrowingOnBadAlloc()) {
throw MessageBadAlloc(tools::ToString("shmem: could not create a message of size ", size, ", alignment: ", (alignment != 0) ? std::to_string(alignment) : "default", ", free memory: ", boost::apply_visitor(SegmentFreeMemory(), fSegments.at(fSegmentId))));
}
// rateLimiter.maybe_sleep();
std::this_thread::sleep_for(std::chrono::milliseconds(50));
if (Interrupted()) {
return ShmPtr(ptr);
throw MessageBadAlloc(tools::ToString("shmem: could not create a message of size ", size, ", alignment: ", (alignment != 0) ? std::to_string(alignment) : "default", ", free memory: ", boost::apply_visitor(SegmentFreeMemory(), fSegments.at(fSegmentId))));
} else {
continue;
}
@@ -684,18 +723,20 @@ class Manager
(*fMsgDebug).emplace(fSegmentId, fShmVoidAlloc);
}
(*fMsgDebug).at(fSegmentId).emplace(
static_cast<size_t>(GetHandleFromAddress(ShmPtr(ptr).UserPtr(), fSegmentId)),
static_cast<size_t>(GetHandleFromAddress(ShmHeader::UserPtr(ptr), fSegmentId)),
MsgDebug(getpid(), size, std::chrono::system_clock::now().time_since_epoch().count())
);
#endif
}
return ShmPtr(ptr);
return ptr;
}
void Deallocate(boost::interprocess::managed_shared_memory::handle_t handle, uint16_t segmentId)
{
boost::apply_visitor(SegmentDeallocate(GetAddressFromHandle(handle, segmentId)), fSegments.at(segmentId));
char* ptr = GetAddressFromHandle(handle, segmentId);
ShmHeader::Destruct(ptr);
boost::apply_visitor(SegmentDeallocate(ptr), fSegments.at(segmentId));
#ifdef FAIRMQ_DEBUG_MODE
boost::interprocess::scoped_lock<boost::interprocess::named_mutex> lock(fShmMtx);
DecrementShmMsgCounter(segmentId);