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Disk: ReadDriver: Add unified cache 

Previously, we had to copy an entire block out of the
old cache every time we wanted to read even a single
byte from it.

This ended up being a fairly significant performance
issue, in addition to the fact that the caching code
was duplicated.
add-device-sharing
Paul Hollinsky 2022-04-14 18:22:13 -04:00
parent d45d708446
commit 103f938d69
10 changed files with 316 additions and 245 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
disk/diskreaddriver.cpp
View File

@ -9,14 +9,25 @@ optional<uint64_t> ReadDriver::readLogicalDisk(Communication& com, device_eventh
if(amount == 0)
return 0;
optional<uint64_t> ret;
pos += vsaOffset;
// First read from the cache
optional<uint64_t> ret = readFromCache(pos, into, amount);
if(ret == amount) // Full cache hit, we're done
return ret;
const uint64_t totalAmount = amount;
if(ret.has_value()) { // Partial cache hit
pos += *ret;
into += *ret;
amount -= *ret;
}
// Read into here if we can't read directly into the user buffer
// That would be the case either if we don't want some at the
// beginning or end of the block.
std::vector<uint8_t> alignedReadBuffer;
pos += vsaOffset;
const uint32_t idealBlockSize = getBlockSizeBounds().second;
const uint64_t startBlock = pos / idealBlockSize;
const uint32_t posWithinFirstBlock = static_cast<uint32_t>(pos % idealBlockSize);
@ -36,7 +47,7 @@ optional<uint64_t> ReadDriver::readLogicalDisk(Communication& com, device_eventh
const uint32_t posWithinCurrentBlock = (blocksProcessed ? 0 : posWithinFirstBlock);
uint32_t curAmt = idealBlockSize - posWithinCurrentBlock;
const auto amountLeft = amount - ret.value_or(0);
const auto amountLeft = totalAmount - ret.value_or(0);
if(curAmt > amountLeft)
curAmt = static_cast<uint32_t>(amountLeft);
@ -65,7 +76,41 @@ optional<uint64_t> ReadDriver::readLogicalDisk(Communication& com, device_eventh
ret.emplace();
*ret += std::min<uint64_t>(*readAmount, curAmt);
blocksProcessed++;
if(blocksProcessed == blocks) {
// Last block, add to the cache
if(useAlignedReadBuffer) {
cache = std::move(alignedReadBuffer);
} else {
if(cache.size() != idealBlockSize)
cache.resize(idealBlockSize);
memcpy(cache.data(), into + intoOffset, idealBlockSize);
}
cachePos = currentBlock * idealBlockSize;
cachedAt = std::chrono::steady_clock::now();
}
}
return ret;
}
void ReadDriver::invalidateCache(uint64_t pos, uint64_t amount) {
if(pos <= cachePos + cache.size() && pos + amount >= cachePos)
cache.clear();
}
optional<uint64_t> ReadDriver::readFromCache(uint64_t pos, uint8_t* into, uint64_t amount, std::chrono::milliseconds staleAfter) {
if(cache.empty())
return nullopt; // Nothing in the cache
if(cachedAt + staleAfter < std::chrono::steady_clock::now())
return nullopt; // Cache is stale
if(pos > cachePos + cache.size() || pos < cachePos)
return nullopt; // Cache miss
const auto cacheOffset = pos - cachePos;
const auto copyAmount = std::min<uint64_t>(cache.size() - cacheOffset, amount);
memcpy(into, cache.data() + cacheOffset, static_cast<size_t>(copyAmount));
return copyAmount;
}

5
disk/diskwritedriver.cpp
View File

@ -75,6 +75,7 @@ optional<uint64_t> WriteDriver::writeLogicalDisk(Communication& com, device_even
if(bytesTransferred == RetryAtomic) {
// The user may want to log these events in order to see how many atomic misses they are getting
report(APIEvent::Type::AtomicOperationRetried, APIEvent::Severity::EventInfo);
readDriver.invalidateCache(currentBlock * idealBlockSize, idealBlockSize);
continue;
}
@ -93,5 +94,9 @@ optional<uint64_t> WriteDriver::writeLogicalDisk(Communication& com, device_even
blocksProcessed++;
}
// No matter how much succeeded, to be safe, we'll invalidate anything
// we may have even tried to write, since it may have succeeded without
// notifying, etc.
readDriver.invalidateCache(pos, amount);
return ret;
}

9
disk/extextractordiskreaddriver.cpp
View File

@ -37,7 +37,6 @@ optional<uint64_t> ExtExtractorDiskReadDriver::attemptReadLogicalDiskAligned(Com
uint64_t pos, uint8_t* into, uint64_t amount, std::chrono::milliseconds timeout) {
static std::shared_ptr<MessageFilter> NeoMemorySDRead = std::make_shared<MessageFilter>(Network::NetID::NeoMemorySDRead);
if(cachePos != pos || std::chrono::steady_clock::now() > cachedAt + CacheTime) {
uint64_t sector = pos / SectorSize;
uint64_t largeSectorCount = amount / SectorSize;
@ -45,7 +44,6 @@ optional<uint64_t> ExtExtractorDiskReadDriver::attemptReadLogicalDiskAligned(Com
if (largeSectorCount != uint64_t(sectorCount))
return nullopt;
// The cache does not have this data, go get it
std::mutex m;
std::condition_variable cv;
uint16_t receiving = 0; // How much are we about to get before another header or completion
@ -146,7 +144,7 @@ optional<uint64_t> ExtExtractorDiskReadDriver::attemptReadLogicalDiskAligned(Com
#ifdef ICSNEO_EXTENDED_EXTRACTOR_DEBUG_PRINTS
std::cout << "With " << int(left) << " bytes " << int(offset) << std::endl;
#endif
memcpy(cache.data() + received, data.data() + offset, count);
memcpy(into + received, data.data() + offset, count);
received += count;
receivedCurrent += count;
offset += count;
@ -204,10 +202,5 @@ optional<uint64_t> ExtExtractorDiskReadDriver::attemptReadLogicalDiskAligned(Com
if(hitTimeout || error)
return nullopt;
cachedAt = std::chrono::steady_clock::now();
cachePos = pos;
}
memcpy(into, cache.data(), size_t(amount));
return amount;
}

13
disk/neomemorydiskdriver.cpp
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@ -15,8 +15,6 @@ optional<uint64_t> NeoMemoryDiskDriver::readLogicalDiskAligned(Communication& co
if(amount != SectorSize)
return nullopt;
if(cachePos != pos || std::chrono::steady_clock::now() > cachedAt + CacheTime) {
// The cache does not have this data, go get it
const uint64_t currentSector = pos / SectorSize;
auto msg = com.waitForMessageSync([&currentSector, &com] {
return com.sendCommand(Command::NeoReadMemory, {
@ -41,12 +39,7 @@ optional<uint64_t> NeoMemoryDiskDriver::readLogicalDiskAligned(Communication& co
return nullopt;
}
memcpy(cache.data(), sdmsg->data.data(), SectorSize);
cachedAt = std::chrono::steady_clock::now();
cachePos = pos;
}
memcpy(into, cache.data(), SectorSize);
memcpy(into, sdmsg->data.data(), SectorSize);
return SectorSize;
}
@ -61,10 +54,6 @@ optional<uint64_t> NeoMemoryDiskDriver::writeLogicalDiskAligned(Communication& c
if(amount != SectorSize)
return nullopt;
// Clear the cache if we're writing to the cached sector
if(pos == cachePos)
cachedAt = std::chrono::time_point<std::chrono::steady_clock>();
// Requesting an atomic operation, but neoMemory does not support it
// Continue on anyway but warn the caller
if(atomicBuf != nullptr)

14
disk/plasiondiskreaddriver.cpp
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@ -19,13 +19,11 @@ optional<uint64_t> PlasionDiskReadDriver::readLogicalDiskAligned(Communication&
if(pos % getBlockSizeBounds().first != 0)
return nullopt;
if(cachePos != pos || std::chrono::steady_clock::now() > cachedAt + CacheTime) {
uint64_t largeSector = pos / SectorSize;
uint32_t sector = uint32_t(largeSector);
if (largeSector != uint64_t(sector))
return nullopt;
// The cache does not have this data, go get it
std::mutex m;
std::condition_variable cv;
uint32_t copied = 0;
@ -35,17 +33,14 @@ optional<uint64_t> PlasionDiskReadDriver::readLogicalDiskAligned(Communication&
std::unique_lock<std::mutex> lk(m);
const auto sdmsg = std::dynamic_pointer_cast<NeoReadMemorySDMessage>(msg);
if(!sdmsg || cache.size() < copied + sdmsg->data.size()) {
if(!sdmsg || amount < copied + sdmsg->data.size()) {
error = true;
lk.unlock();
cv.notify_all();
return;
}
// Invalidate the cache here in case we fail half-way through
cachedAt = std::chrono::steady_clock::time_point();
memcpy(cache.data() + copied, sdmsg->data.data(), sdmsg->data.size());
memcpy(into + copied, sdmsg->data.data(), sdmsg->data.size());
copied += uint32_t(sdmsg->data.size());
if(copied == amount) {
lk.unlock();
@ -69,10 +64,5 @@ optional<uint64_t> PlasionDiskReadDriver::readLogicalDiskAligned(Communication&
if(hitTimeout)
return nullopt;
cachedAt = std::chrono::steady_clock::now();
cachePos = pos;
}
memcpy(into, cache.data(), size_t(amount));
return amount;
}

12
include/icsneo/disk/diskreaddriver.h
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@ -22,6 +22,9 @@ public:
virtual optional<uint64_t> readLogicalDisk(Communication& com, device_eventhandler_t report,
uint64_t pos, uint8_t* into, uint64_t amount, std::chrono::milliseconds timeout = DefaultTimeout);
void invalidateCache(uint64_t pos = 0,
uint64_t amount = std::numeric_limits<uint32_t>::max() /* large value, but avoid overflow */);
protected:
/**
* Perform a read which the driver can do in one shot.
@ -31,6 +34,15 @@ protected:
*/
virtual optional<uint64_t> readLogicalDiskAligned(Communication& com, device_eventhandler_t report,
uint64_t pos, uint8_t* into, uint64_t amount, std::chrono::milliseconds timeout) = 0;
private:
std::vector<uint8_t> cache;
uint64_t cachePos = 0;
std::chrono::time_point<std::chrono::steady_clock> cachedAt;
static constexpr const std::chrono::milliseconds CacheTime = std::chrono::milliseconds(1000);
optional<uint64_t> readFromCache(uint64_t pos, uint8_t* into, uint64_t amount, std::chrono::milliseconds staleAfter = CacheTime);
};
} // namespace Disk

5
include/icsneo/disk/extextractordiskreaddriver.h
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@ -24,13 +24,8 @@ public:
private:
static constexpr const uint32_t MaxSize = Disk::SectorSize * 512;
static constexpr const std::chrono::seconds CacheTime = std::chrono::seconds(1);
static constexpr const uint8_t HeaderLength = 7;
std::array<uint8_t, MaxSize> cache;
uint64_t cachePos = 0;
std::chrono::time_point<std::chrono::steady_clock> cachedAt;
Access getPossibleAccess() const override { return Access::EntireCard; }
optional<uint64_t> readLogicalDiskAligned(Communication& com, device_eventhandler_t report,

5
include/icsneo/disk/neomemorydiskdriver.h
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@ -27,11 +27,6 @@ public:
private:
static constexpr const uint8_t MemoryTypeSD = 0x01; // Logical Disk
static constexpr const std::chrono::seconds CacheTime = std::chrono::seconds(1);
std::array<uint8_t, SectorSize> cache;
uint64_t cachePos = 0;
std::chrono::time_point<std::chrono::steady_clock> cachedAt;
Access getPossibleAccess() const override { return Access::VSA; }

5
include/icsneo/disk/plasiondiskreaddriver.h
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@ -24,11 +24,6 @@ public:
private:
static constexpr const uint32_t MaxSize = 65024;
static constexpr const std::chrono::seconds CacheTime = std::chrono::seconds(1);
std::array<uint8_t, MaxSize> cache;
uint64_t cachePos = 0;
std::chrono::time_point<std::chrono::steady_clock> cachedAt;
Access getPossibleAccess() const override { return Access::EntireCard; }

52
test/diskdriverreadtest.cpp
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@ -62,3 +62,55 @@ TEST_F(DiskDriverTest, ReadBadStartingPos) {
EXPECT_FALSE(amountRead.has_value());
EXPECT_EQ(driver->readCalls, 1u); // One to check EOF
}
TEST_F(DiskDriverTest, ReadCache) {
std::array<uint8_t, 128> buf;
buf.fill(0u);
auto amountRead = readLogicalDisk(1, buf.data(), buf.size());
EXPECT_TRUE(amountRead.has_value());
EXPECT_EQ(amountRead, buf.size());
EXPECT_EQ(buf[0], TEST_STRING[1]);
EXPECT_EQ(buf[110], 111u);
EXPECT_EQ(driver->readCalls, 1u);
// Subsequent reads (within the same second) should hit the cache
amountRead = readLogicalDisk(1, buf.data(), buf.size());
EXPECT_EQ(driver->readCalls, 1u);
// The underlying data can be changed
driver->mockDisk[1] = 'J';
// But the same data should be returned from the cache
amountRead = readLogicalDisk(1, buf.data(), buf.size());
EXPECT_TRUE(amountRead.has_value());
EXPECT_EQ(amountRead, buf.size());
EXPECT_EQ(buf[0], TEST_STRING[1]);
EXPECT_EQ(buf[110], 111u);
EXPECT_EQ(driver->readCalls, 1u);
driver->invalidateCache(0, 0xfffff);
// After invalidating the cache (or waiting for it to expire), the underlying data will be read
amountRead = readLogicalDisk(1, buf.data(), buf.size());
EXPECT_TRUE(amountRead.has_value());
EXPECT_EQ(amountRead, buf.size());
EXPECT_EQ(buf[0], 'J');
EXPECT_EQ(buf[110], 111u);
EXPECT_EQ(driver->readCalls, 2u);
}
TEST_F(DiskDriverTest, ReadCacheLong) {
std::array<uint8_t, 500> buf;
buf.fill(0u);
auto amountRead = readLogicalDisk(300, buf.data(), buf.size());
EXPECT_TRUE(amountRead.has_value());
EXPECT_EQ(amountRead, buf.size());
EXPECT_EQ(buf[0], 300 & 0xFF);
EXPECT_EQ(buf[110], 410 & 0xFF);
EXPECT_EQ(driver->readCalls, 3u);
// Re-read the end, it will be in the cache
amountRead = readLogicalDisk(780, buf.data() + 480, buf.size() - 480);
EXPECT_EQ(buf[490], 790 & 0xFF);
EXPECT_EQ(driver->readCalls, 3u);
}