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block_session: server-defined payload alignment

Browse Source 
This patch replaces the formerly fixed 2 KiB data alignment within the
packet-stream buffer by a server-defined alignment. This has two
benefits.

First, when using block servers that provide small block sizes like 512
bytes, we avoid fragmenting the packet-stream buffer, which occurs when
aligning 512-byte requests at 2 KiB boundaries. This reduces meta data
costs for the packet-stream allocator and also allows fitting more
requests into the buffer.

Second, block drivers with alignment constraints dictated by the
hardware can now pass those constraints to the client, thereby easing
the use of zero-copy DMA directly into the packet stream.

The alignment is determined by the Block::Session_client at construction
time and applied by the Block::Session_client::alloc_packet method.
Block-session clients should always use this method, not the 'alloc_packet'
method of the packet stream (tx source) directly. The latter merely
applies a default alignment of 2 KiB.

At the server side, the alignment is automatically checked by
block/component.h (old API) and block/request_stream.h (new API).

Issue #3274
This commit is contained in:
Norman Feske 2019-04-04 18:25:54 +02:00 committed by Christian Helmuth
parent 2208220c12
commit bbe3ee8dc5
35 changed files with 68 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
repos/dde_linux/src/lib/usb/storage/storage.cc
View File

@ -148,6 +148,7 @@ class Storage_device : public Genode::List<Storage_device>::Element,
{
return { .block_size = _block_size,
.block_count = _block_count,
.align_log2 = Genode::log2(_block_size),
.writeable = true };
}

2
repos/dde_rump/src/lib/rump/io.cc
View File

@ -57,7 +57,7 @@ class Backend
Packet_descriptor::READ;
/* allocate packet */
try {
Packet_descriptor packet( _session.dma_alloc_packet(length),
Packet_descriptor packet( _session.alloc_packet(length),
opcode, offset / _info.block_size,
length / _info.block_size);

1
repos/gems/src/server/http_block/main.cc
View File

@ -46,6 +46,7 @@ class Driver : public Block::Driver
{
return { .block_size = _block_size,
.block_count = _http.file_size() / _block_size,
.align_log2 = log2(_block_size),
.writeable = false };
}

5
repos/libports/src/lib/fatfs/diskio_block.cc
View File

@ -62,6 +62,7 @@ extern "C" {
using Block::Connection::tx;
using Block::Connection::sync;
using Block::Connection::alloc_packet;
Drive(Platform &platform, char const *label)
: Block::Connection(platform.env, &platform.tx_alloc, 128*1024, label)
@ -125,7 +126,7 @@ extern "C" DRESULT disk_read (BYTE pdrv, BYTE* buff, DWORD sector, UINT count)
Genode::size_t const op_len = drive.info.block_size*count;
/* allocate packet-descriptor for reading */
Block::Packet_descriptor p(drive.tx()->alloc_packet(op_len),
Block::Packet_descriptor p(drive.alloc_packet(op_len),
Block::Packet_descriptor::READ, sector, count);
drive.tx()->submit_packet(p);
p = drive.tx()->get_acked_packet();
@ -155,7 +156,7 @@ extern "C" DRESULT disk_write (BYTE pdrv, const BYTE* buff, DWORD sector, UINT c
Genode::size_t const op_len = drive.info.block_size*count;
/* allocate packet-descriptor for writing */
Block::Packet_descriptor p(drive.tx()->alloc_packet(op_len),
Block::Packet_descriptor p(drive.alloc_packet(op_len),
Block::Packet_descriptor::WRITE, sector, count);
Genode::memcpy(drive.tx()->packet_content(p), buff, op_len);

3
repos/os/include/block/component.h
View File

@ -108,7 +108,8 @@ class Block::Session_component : public Block::Session_component_base,
/* ignore invalid packets */
bool const valid = packet.size() && _range_check(_p_to_handle)
&& tx_sink()->packet_valid(packet);
&& tx_sink()->packet_valid(packet)
&& aligned(packet.offset(), _info.align_log2);
if (!valid) {
_ack_packet(_p_to_handle);
return;

11
repos/os/include/block/request_stream.h
View File

@ -26,6 +26,9 @@ class Block::Request_stream : Genode::Noncopyable
{
public:
struct Block_size { Genode::uint32_t value; };
struct Align_log2 { Genode::size_t value; };
/**
* Interface for accessing the content of a 'Request'
*
@ -59,7 +62,7 @@ class Block::Request_stream : Genode::Noncopyable
return request.count * _info.block_size;
}
bool _valid_range(Block::Request const &request) const
bool _valid_range_and_alignment(Block::Request const &request) const
{
/* local address of the last byte of the request */
Genode::addr_t const request_end = _base + request.offset
@ -73,6 +76,10 @@ class Block::Request_stream : Genode::Noncopyable
if (request_end > _base + _size - 1)
return false;
/* check for proper alignment */
if (!Genode::aligned(request.offset, _info.align_log2))
return false;
return true;
}
@ -94,7 +101,7 @@ class Block::Request_stream : Genode::Noncopyable
template <typename FN>
void with_content(Block::Request request, FN const &fn) const
{
if (_valid_range(request))
if (_valid_range_and_alignment(request))
fn(_request_ptr(request), _request_size(request));
}
};

13
repos/os/include/block_session/block_session.h
View File

@ -31,7 +31,7 @@ namespace Block {
/**
* Represents an block-operation request
* Representation of an block-operation request
*
* The data associated with the 'Packet_descriptor' is either
* the data read from or written to the block indicated by
@ -42,6 +42,14 @@ class Block::Packet_descriptor : public Genode::Packet_descriptor
public:
enum Opcode { READ, WRITE, END };
/*
* Alignment used when allocating a packet directly via the 'tx'
* packet stream. This is not recommended because it does not
* apply the server's alignment constraints. Instead, the
* 'Block::Session_client::alloc_packet' should be used for
* allocating properly aligned block-request packets.
*/
enum Alignment { PACKET_ALIGNMENT = 11 };
private:
@ -82,7 +90,7 @@ class Block::Packet_descriptor : public Genode::Packet_descriptor
};
/*
/**
* Block session interface
*
* A block session corresponds to a block device that can be used to read
@ -109,6 +117,7 @@ struct Block::Session : public Genode::Session
{
Genode::size_t block_size; /* size of one block in bytes */
sector_t block_count; /* number of blocks */
Genode::size_t align_log2; /* packet alignment within payload buffer */
bool writeable;
};

10
repos/os/include/block_session/client.h
View File

@ -27,6 +27,8 @@ class Block::Session_client : public Genode::Rpc_client<Session>
Packet_stream_tx::Client<Tx> _tx;
Info const _info = info();
public:
/**
@ -59,12 +61,12 @@ class Block::Session_client : public Genode::Rpc_client<Session>
Genode::Capability<Tx> tx_cap() override { return call<Rpc_tx_cap>(); }
/*
* Wrapper for alloc_packet, allocates 2KB aligned packets
/**
* Allocate packet respecting the server's alignment constraints
*/
Packet_descriptor dma_alloc_packet(Genode::size_t size)
Packet_descriptor alloc_packet(Genode::size_t size)
{
return tx()->alloc_packet(size, 11);
return tx()->alloc_packet(size, _info.align_log2);
}
};

2
repos/os/src/app/block_tester/test_ping_pong.h
View File

@ -63,7 +63,7 @@ struct Test::Ping_pong : Test_base
while (_blocks < _length_in_blocks && _block->tx()->ready_to_submit()) {
Block::Packet_descriptor tmp =
_block->tx()->alloc_packet(_size_in_blocks * _info.block_size);
_block->alloc_packet(_size_in_blocks * _info.block_size);
Block::sector_t const lba = _ping ? _start + _blocks
: _end - _blocks;

3
repos/os/src/app/block_tester/test_random.h
View File

@ -127,8 +127,7 @@ struct Test::Random : Test_base
bool next = true;
while (_blocks < _length_in_blocks && _block->tx()->ready_to_submit() && next) {
Block::Packet_descriptor tmp =
_block->tx()->alloc_packet(_size);
Block::Packet_descriptor tmp = _block->alloc_packet(_size);
Block::sector_t lba = _next_block();

2
repos/os/src/app/block_tester/test_replay.h
View File

@ -69,7 +69,7 @@ struct Test::Replay : Test_base
more = false;
requests.dequeue([&] (Request &req) {
Block::Packet_descriptor p(
_block->tx()->alloc_packet(req.count * _info.block_size),
_block->alloc_packet(req.count * _info.block_size),
req.op, req.nr, req.count);
bool const write = req.op == Block::Packet_descriptor::WRITE;

3
repos/os/src/app/block_tester/test_sequential.h
View File

@ -66,8 +66,7 @@ struct Test::Sequential : Test_base
bool next = true;
while (_blocks < _length_in_blocks && _block->tx()->ready_to_submit() && next) {
Block::Packet_descriptor tmp =
_block->tx()->alloc_packet(_size);
Block::Packet_descriptor tmp = _block->alloc_packet(_size);
Block::Packet_descriptor p(tmp,
_op, _start, _size_in_blocks);

1
repos/os/src/drivers/ahci/ata_driver.h
View File

@ -377,6 +377,7 @@ struct Ata_driver : Port_driver
{
return { .block_size = block_size(),
.block_count = block_count(),
.align_log2 = log2(block_size()),
.writeable = true };
}

1
repos/os/src/drivers/ahci/atapi_driver.h
View File

@ -162,6 +162,7 @@ struct Atapi_driver : Port_driver
{
return { .block_size = block_size(),
.block_count = block_count(),
.align_log2 = 11,
.writeable = false };
}

1
repos/os/src/drivers/nvme/main.cc
View File

@ -1541,6 +1541,7 @@ class Driver : public Block::Driver
_info = { .block_size = nsinfo.size,
.block_count = nsinfo.count,
.align_log2 = Genode::log2(nsinfo.size),
.writeable = true };
Nvme::Controller::Info const &info = _nvme_ctrlr->info();

1
repos/os/src/drivers/sd_card/driver_base.h
View File

@ -48,6 +48,7 @@ class Sd_card::Driver_base : public Block::Driver,
{
return { .block_size = _block_size(),
.block_count = _block_count(),
.align_log2 = Genode::log2(_block_size()),
.writeable = true };
}
};

1
repos/os/src/drivers/sd_card/spec/pbxa9/driver.h
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@ -129,6 +129,7 @@ class Sd_card::Driver : public Block::Driver, private Attached_mmio
{
return { .block_size = _block_size,
.block_count = _block_count,
.align_log2 = log2(_block_size),
.writeable = true };
}

1
repos/os/src/drivers/usb_block/main.cc
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@ -808,6 +808,7 @@ struct Usb::Block_driver : Usb::Completion,
{
return { .block_size = _block_size,
.block_count = _block_count,
.align_log2 = Genode::log2(_block_size),
.writeable = _writeable };
}

2
repos/os/src/lib/vfs/block_file_system.h
View File

@ -106,7 +106,7 @@ class Vfs::Block_file_system : public Single_file_system
try {
Lock::Guard guard(_lock);
packet = _tx_source->alloc_packet(packet_size);
packet = _block.alloc_packet(packet_size);
break;
} catch (Block::Session::Tx::Source::Packet_alloc_failed) {
if (!_tx_source->ready_to_submit())

2
repos/os/src/server/block_cache/driver.h
View File

@ -244,7 +244,7 @@ class Driver : public Block::Driver
/* construct and send the packet */
p_to_dev =
Block::Packet_descriptor(_blk.dma_alloc_packet(_info.block_size*cnt),
Block::Packet_descriptor(_blk.alloc_packet(_info.block_size*cnt),
Block::Packet_descriptor::READ,
nr, cnt);
_r_list.insert(new (&_r_slab) Request(p_to_dev, packet, buffer));

2
repos/os/src/server/block_cache/main.cc
View File

@ -35,7 +35,7 @@ void Driver<POLICY>::Policy::sync(const typename POLICY::Element *e, char *dst)
throw Write_failed(off);
try {
Block::Packet_descriptor
p(driver->blk()->dma_alloc_packet(Driver::CACHE_BLK_SIZE),
p(driver->blk()->alloc_packet(Driver::CACHE_BLK_SIZE),
Block::Packet_descriptor::WRITE, off / driver->blk_sz(),
Driver::CACHE_BLK_SIZE / driver->blk_sz());
driver->blk()->tx()->submit_packet(p);

2
repos/os/src/server/iso9660/iso9660.cc
View File

@ -56,7 +56,7 @@ class Iso::Sector {
{
try {
_p = Block::Packet_descriptor(
block.dma_alloc_packet(blk_size() * count),
block.alloc_packet(blk_size() * count),
Block::Packet_descriptor::READ,
blk_nr * ((float)blk_size() / BLOCK_SIZE),
count * ((float)blk_size() / BLOCK_SIZE));

1
repos/os/src/server/lx_block/main.cc
View File

@ -73,6 +73,7 @@ class Lx_block_driver : public Block::Driver
return {
.block_size = block_size,
.block_count = st.st_size / block_size,
.align_log2 = Genode::log2(block_size),
.writeable = xml_attr_ok(config, "writeable")
};
}

1
repos/os/src/server/part_block/component.h
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@ -220,6 +220,7 @@ class Block::Session_component : public Block::Session_rpc_object,
{
return Info { .block_size = _driver.blk_size(),
.block_count = _partition->sectors,
.align_log2 = Genode::log2(_driver.blk_size()),
.writeable = _writeable && _driver.writeable() };
}

2
repos/os/src/server/part_block/driver.h
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@ -139,7 +139,7 @@ class Block::Driver
? Block::Packet_descriptor::WRITE
: Block::Packet_descriptor::READ;
Genode::size_t const size = _info.block_size * cnt;
Packet_descriptor p(_session.dma_alloc_packet(size),
Packet_descriptor p(_session.alloc_packet(size),
op, nr, cnt);
Request *r = new (&_r_slab) Request(dispatcher, cli, p);
_r_list.insert(r);

2
repos/os/src/server/part_block/partition_table.h
View File

@ -54,7 +54,7 @@ struct Block::Partition_table : Genode::Interface
unsigned long count,
bool write = false)
: _session(driver.session()),
_p(_session.dma_alloc_packet(driver.blk_size() * count),
_p(_session.alloc_packet(driver.blk_size() * count),
write ? Packet_descriptor::WRITE : Packet_descriptor::READ,
blk_nr, count)
{

1
repos/os/src/server/ram_block/main.cc
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@ -116,6 +116,7 @@ class Ram_block : public Block::Driver
{
return { .block_size = _block_size,
.block_count = _block_count,
.align_log2 = log2(_block_size),
.writeable = true };
}

1
repos/os/src/server/rom_block/main.cc
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@ -48,6 +48,7 @@ class Rom_block : public Block::Driver
{
return { .block_size = _blk_sz,
.block_count = _blk_cnt,
.align_log2 = log2(_blk_sz),
.writeable = false };
}

2
repos/os/src/server/tz_vmm/block_driver.cc
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@ -175,7 +175,7 @@ void Block_driver::_new_request(Vm_base &vm)
size_t const size = vm.smc_arg_3();
void *const req = (void*)vm.smc_arg_4();
Packet_descriptor pkt = dev.session().tx()->alloc_packet(size);
Packet_descriptor pkt = dev.session().alloc_packet(size);
void *addr = dev.session().tx()->packet_content(pkt);
dev.cache().insert(addr, req);
vm.smc_ret((long)addr, pkt.offset());

2
repos/os/src/test/block/bench/main.cc
View File

@ -67,7 +67,7 @@ class Throughput
try {
while (_session.tx()->ready_to_submit()) {
Block::Packet_descriptor p(
_session.tx()->alloc_packet(REQUEST_SIZE),
_session.alloc_packet(REQUEST_SIZE),
!_read_done ? Block::Packet_descriptor::READ : Block::Packet_descriptor::WRITE,
_current, count);

15
repos/os/src/test/block/client/main.cc
View File

@ -140,7 +140,7 @@ struct Read_test : Test
try {
Block::Packet_descriptor p(
_session.dma_alloc_packet(cnt*blk_sz),
_session.alloc_packet(cnt*blk_sz),
Block::Packet_descriptor::READ, nr, cnt);
_session.tx()->submit_packet(p);
} catch(Block::Session::Tx::Source::Packet_alloc_failed) {
@ -241,8 +241,7 @@ struct Write_test : Test
{
while (!read_packets.empty()) {
Block::Packet_descriptor r = read_packets.get();
Block::Packet_descriptor w(_session.dma_alloc_packet(r.block_count()
*blk_sz),
Block::Packet_descriptor w(_session.alloc_packet(r.block_count()*blk_sz),
Block::Packet_descriptor::WRITE,
r.block_number(), r.block_count());
signed char *dst = (signed char*)_session.tx()->packet_content(w),
@ -263,7 +262,7 @@ struct Write_test : Test
for (sector_t nr = start, cnt = Genode::min(NR_PER_REQ, end - start); nr < end;
nr += cnt,
cnt = Genode::min<sector_t>(NR_PER_REQ, end-nr)) {
Block::Packet_descriptor p(_session.dma_alloc_packet(cnt*blk_sz),
Block::Packet_descriptor p(_session.alloc_packet(cnt*blk_sz),
Block::Packet_descriptor::READ, nr, cnt);
_session.tx()->submit_packet(p);
}
@ -338,10 +337,10 @@ struct Violation_test : Test
void req(Block::sector_t nr, Genode::size_t cnt, bool write)
{
Block::Packet_descriptor p(_session.dma_alloc_packet(blk_sz),
write ? Block::Packet_descriptor::WRITE
: Block::Packet_descriptor::READ,
nr, cnt);
Block::Packet_descriptor p(_session.alloc_packet(blk_sz),
write ? Block::Packet_descriptor::WRITE
: Block::Packet_descriptor::READ,
nr, cnt);
_session.tx()->submit_packet(p);
p_in_fly++;
}

1
repos/os/src/test/block/server/main.cc
View File

@ -67,6 +67,7 @@ class Driver : public Block::Driver
{
return { .block_size = _size,
.block_count = _number,
.align_log2 = Genode::log2(_size),
.writeable = true };
}

1
repos/os/src/test/block_request_stream/main.cc
View File

@ -44,6 +44,7 @@ struct Test::Block_session_component : Rpc_object<Block::Session>,
Request_stream(rm, ds, ep, sigh,
Info { .block_size = BLOCK_SIZE,
.block_count = NUM_BLOCKS,
.align_log2 = log2(BLOCK_SIZE),
.writeable = true }),
_ep(ep)
{

2
repos/os/src/test/rom_block/main.cc
View File

@ -56,7 +56,7 @@ struct Main
size_t const cnt = (info.block_count - i > REQ_PARALLEL)
? REQ_PARALLEL : info.block_count - i;
Packet_descriptor pkt(src.alloc_packet(cnt * info.block_size),
Packet_descriptor pkt(block.alloc_packet(cnt * info.block_size),
Packet_descriptor::READ, i, cnt);
log("Check blocks ", i, "..", i + cnt - 1);

4
repos/ports/src/app/seoul/disk.cc
View File

@ -260,7 +260,7 @@ bool Seoul::Disk::restart(struct disk_session const &disk,
Genode::Lock::Guard lock_guard(_alloc_lock);
packet = Block::Packet_descriptor(
source->alloc_packet(blocks * blk_size),
disk.blk_con->alloc_packet(blocks * blk_size),
(write) ? Block::Packet_descriptor::WRITE
: Block::Packet_descriptor::READ,
msg->sector, blocks);
@ -317,7 +317,7 @@ bool Seoul::Disk::execute(bool const write, struct disk_session const &disk,
Genode::Lock::Guard lock_guard(_alloc_lock);
packet = Block::Packet_descriptor(
source->alloc_packet(blocks * blk_size),
disk.blk_con->alloc_packet(blocks * blk_size),
(write) ? Block::Packet_descriptor::WRITE
: Block::Packet_descriptor::READ,
sector, blocks);