gem5/src/mem/physical.cc
Andreas Hansson 88aa7755f4 mem: Avoid explicitly zeroing the memory backing store
This patch removes the explicit memset as it is redundant and causes
the simulator to touch the entire space, forcing the host system to
allocate the pages.

Anonymous pages are mapped on the first access, and the page-fault
handler is responsible for zeroing them. Thus, the pages are still
zeroed, but we avoid touching the entire allocated space which enables
us to use much larger memory sizes as long as not all the memory is
actually used.
2013-05-30 12:53:54 -04:00

449 lines
16 KiB
C++

/*
* Copyright (c) 2012 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Andreas Hansson
*/
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/user.h>
#include <fcntl.h>
#include <unistd.h>
#include <zlib.h>
#include <cerrno>
#include <climits>
#include <cstdio>
#include <iostream>
#include <string>
#include "base/trace.hh"
#include "debug/BusAddrRanges.hh"
#include "debug/Checkpoint.hh"
#include "mem/abstract_mem.hh"
#include "mem/physical.hh"
using namespace std;
PhysicalMemory::PhysicalMemory(const string& _name,
const vector<AbstractMemory*>& _memories) :
_name(_name), size(0)
{
// add the memories from the system to the address map as
// appropriate
for (vector<AbstractMemory*>::const_iterator m = _memories.begin();
m != _memories.end(); ++m) {
// only add the memory if it is part of the global address map
if ((*m)->isInAddrMap()) {
memories.push_back(*m);
// calculate the total size once and for all
size += (*m)->size();
// add the range to our interval tree and make sure it does not
// intersect an existing range
if (addrMap.insert((*m)->getAddrRange(), *m) == addrMap.end())
fatal("Memory address range for %s is overlapping\n",
(*m)->name());
} else {
DPRINTF(BusAddrRanges,
"Skipping memory %s that is not in global address map\n",
(*m)->name());
// this type of memory is used e.g. as reference memory by
// Ruby, and they also needs a backing store, but should
// not be part of the global address map
// simply do it independently, also note that this kind of
// memories are allowed to overlap in the logic address
// map
vector<AbstractMemory*> unmapped_mems;
unmapped_mems.push_back(*m);
createBackingStore((*m)->getAddrRange(), unmapped_mems);
}
}
// iterate over the increasing addresses and chunks of contigous
// space to be mapped to backing store, also remember what
// memories constitute the range so we can go and find out if we
// have to init their parts to zero
vector<AddrRange> intlv_ranges;
vector<AbstractMemory*> curr_memories;
for (AddrRangeMap<AbstractMemory*>::const_iterator r = addrMap.begin();
r != addrMap.end(); ++r) {
// simply skip past all memories that are null and hence do
// not need any backing store
if (!r->second->isNull()) {
// if the range is interleaved then save it for now
if (r->first.interleaved()) {
// if we already got interleaved ranges that are not
// part of the same range, then first do a merge
// before we add the new one
if (!intlv_ranges.empty() &&
!intlv_ranges.back().mergesWith(r->first)) {
AddrRange merged_range(intlv_ranges);
createBackingStore(merged_range, curr_memories);
intlv_ranges.clear();
curr_memories.clear();
}
intlv_ranges.push_back(r->first);
curr_memories.push_back(r->second);
} else {
vector<AbstractMemory*> single_memory;
single_memory.push_back(r->second);
createBackingStore(r->first, single_memory);
}
}
}
// if there is still interleaved ranges waiting to be merged, go
// ahead and do it
if (!intlv_ranges.empty()) {
AddrRange merged_range(intlv_ranges);
createBackingStore(merged_range, curr_memories);
}
}
void
PhysicalMemory::createBackingStore(AddrRange range,
const vector<AbstractMemory*>& _memories)
{
if (range.interleaved())
panic("Cannot create backing store for interleaved range %s\n",
range.to_string());
// perform the actual mmap
DPRINTF(BusAddrRanges, "Creating backing store for range %s with size %d\n",
range.to_string(), range.size());
int map_flags = MAP_ANON | MAP_PRIVATE;
uint8_t* pmem = (uint8_t*) mmap(NULL, range.size(),
PROT_READ | PROT_WRITE,
map_flags, -1, 0);
if (pmem == (uint8_t*) MAP_FAILED) {
perror("mmap");
fatal("Could not mmap %d bytes for range %s!\n", range.size(),
range.to_string());
}
// remember this backing store so we can checkpoint it and unmap
// it appropriately
backingStore.push_back(make_pair(range, pmem));
// point the memories to their backing store, and if requested,
// initialize the memory range to 0
for (vector<AbstractMemory*>::const_iterator m = _memories.begin();
m != _memories.end(); ++m) {
DPRINTF(BusAddrRanges, "Mapping memory %s to backing store\n",
(*m)->name());
(*m)->setBackingStore(pmem);
}
}
PhysicalMemory::~PhysicalMemory()
{
// unmap the backing store
for (vector<pair<AddrRange, uint8_t*> >::iterator s = backingStore.begin();
s != backingStore.end(); ++s)
munmap((char*)s->second, s->first.size());
}
bool
PhysicalMemory::isMemAddr(Addr addr) const
{
// see if the address is within the last matched range
if (!rangeCache.contains(addr)) {
// lookup in the interval tree
AddrRangeMap<AbstractMemory*>::const_iterator r = addrMap.find(addr);
if (r == addrMap.end()) {
// not in the cache, and not in the tree
return false;
}
// the range is in the tree, update the cache
rangeCache = r->first;
}
assert(addrMap.find(addr) != addrMap.end());
// either matched the cache or found in the tree
return true;
}
AddrRangeList
PhysicalMemory::getConfAddrRanges() const
{
// this could be done once in the constructor, but since it is unlikely to
// be called more than once the iteration should not be a problem
AddrRangeList ranges;
vector<AddrRange> intlv_ranges;
for (AddrRangeMap<AbstractMemory*>::const_iterator r = addrMap.begin();
r != addrMap.end(); ++r) {
if (r->second->isConfReported()) {
// if the range is interleaved then save it for now
if (r->first.interleaved()) {
// if we already got interleaved ranges that are not
// part of the same range, then first do a merge
// before we add the new one
if (!intlv_ranges.empty() &&
!intlv_ranges.back().mergesWith(r->first)) {
ranges.push_back(AddrRange(intlv_ranges));
intlv_ranges.clear();
}
intlv_ranges.push_back(r->first);
} else {
// keep the current range
ranges.push_back(r->first);
}
}
}
// if there is still interleaved ranges waiting to be merged,
// go ahead and do it
if (!intlv_ranges.empty()) {
ranges.push_back(AddrRange(intlv_ranges));
}
return ranges;
}
void
PhysicalMemory::access(PacketPtr pkt)
{
assert(pkt->isRequest());
Addr addr = pkt->getAddr();
AddrRangeMap<AbstractMemory*>::const_iterator m = addrMap.find(addr);
assert(m != addrMap.end());
m->second->access(pkt);
}
void
PhysicalMemory::functionalAccess(PacketPtr pkt)
{
assert(pkt->isRequest());
Addr addr = pkt->getAddr();
AddrRangeMap<AbstractMemory*>::const_iterator m = addrMap.find(addr);
assert(m != addrMap.end());
m->second->functionalAccess(pkt);
}
void
PhysicalMemory::serialize(ostream& os)
{
// serialize all the locked addresses and their context ids
vector<Addr> lal_addr;
vector<int> lal_cid;
for (vector<AbstractMemory*>::iterator m = memories.begin();
m != memories.end(); ++m) {
const list<LockedAddr>& locked_addrs = (*m)->getLockedAddrList();
for (list<LockedAddr>::const_iterator l = locked_addrs.begin();
l != locked_addrs.end(); ++l) {
lal_addr.push_back(l->addr);
lal_cid.push_back(l->contextId);
}
}
arrayParamOut(os, "lal_addr", lal_addr);
arrayParamOut(os, "lal_cid", lal_cid);
// serialize the backing stores
unsigned int nbr_of_stores = backingStore.size();
SERIALIZE_SCALAR(nbr_of_stores);
unsigned int store_id = 0;
// store each backing store memory segment in a file
for (vector<pair<AddrRange, uint8_t*> >::iterator s = backingStore.begin();
s != backingStore.end(); ++s) {
nameOut(os, csprintf("%s.store%d", name(), store_id));
serializeStore(os, store_id++, s->first, s->second);
}
}
void
PhysicalMemory::serializeStore(ostream& os, unsigned int store_id,
AddrRange range, uint8_t* pmem)
{
// we cannot use the address range for the name as the
// memories that are not part of the address map can overlap
string filename = name() + ".store" + to_string(store_id) + ".pmem";
long range_size = range.size();
DPRINTF(Checkpoint, "Serializing physical memory %s with size %d\n",
filename, range_size);
SERIALIZE_SCALAR(store_id);
SERIALIZE_SCALAR(filename);
SERIALIZE_SCALAR(range_size);
// write memory file
string filepath = Checkpoint::dir() + "/" + filename.c_str();
int fd = creat(filepath.c_str(), 0664);
if (fd < 0) {
perror("creat");
fatal("Can't open physical memory checkpoint file '%s'\n",
filename);
}
gzFile compressed_mem = gzdopen(fd, "wb");
if (compressed_mem == NULL)
fatal("Insufficient memory to allocate compression state for %s\n",
filename);
uint64_t pass_size = 0;
// gzwrite fails if (int)len < 0 (gzwrite returns int)
for (uint64_t written = 0; written < range.size();
written += pass_size) {
pass_size = (uint64_t)INT_MAX < (range.size() - written) ?
(uint64_t)INT_MAX : (range.size() - written);
if (gzwrite(compressed_mem, pmem + written,
(unsigned int) pass_size) != (int) pass_size) {
fatal("Write failed on physical memory checkpoint file '%s'\n",
filename);
}
}
// close the compressed stream and check that the exit status
// is zero
if (gzclose(compressed_mem))
fatal("Close failed on physical memory checkpoint file '%s'\n",
filename);
}
void
PhysicalMemory::unserialize(Checkpoint* cp, const string& section)
{
// unserialize the locked addresses and map them to the
// appropriate memory controller
vector<Addr> lal_addr;
vector<int> lal_cid;
arrayParamIn(cp, section, "lal_addr", lal_addr);
arrayParamIn(cp, section, "lal_cid", lal_cid);
for(size_t i = 0; i < lal_addr.size(); ++i) {
AddrRangeMap<AbstractMemory*>::const_iterator m =
addrMap.find(lal_addr[i]);
m->second->addLockedAddr(LockedAddr(lal_addr[i], lal_cid[i]));
}
// unserialize the backing stores
unsigned int nbr_of_stores;
UNSERIALIZE_SCALAR(nbr_of_stores);
for (unsigned int i = 0; i < nbr_of_stores; ++i) {
unserializeStore(cp, csprintf("%s.store%d", section, i));
}
}
void
PhysicalMemory::unserializeStore(Checkpoint* cp, const string& section)
{
const uint32_t chunk_size = 16384;
unsigned int store_id;
UNSERIALIZE_SCALAR(store_id);
string filename;
UNSERIALIZE_SCALAR(filename);
string filepath = cp->cptDir + "/" + filename;
// mmap memoryfile
int fd = open(filepath.c_str(), O_RDONLY);
if (fd < 0) {
perror("open");
fatal("Can't open physical memory checkpoint file '%s'", filename);
}
gzFile compressed_mem = gzdopen(fd, "rb");
if (compressed_mem == NULL)
fatal("Insufficient memory to allocate compression state for %s\n",
filename);
uint8_t* pmem = backingStore[store_id].second;
AddrRange range = backingStore[store_id].first;
// unmap file that was mmapped in the constructor, this is
// done here to make sure that gzip and open don't muck with
// our nice large space of memory before we reallocate it
munmap((char*) pmem, range.size());
long range_size;
UNSERIALIZE_SCALAR(range_size);
DPRINTF(Checkpoint, "Unserializing physical memory %s with size %d\n",
filename, range_size);
if (range_size != range.size())
fatal("Memory range size has changed! Saw %lld, expected %lld\n",
range_size, range.size());
pmem = (uint8_t*) mmap(NULL, range.size(), PROT_READ | PROT_WRITE,
MAP_ANON | MAP_PRIVATE, -1, 0);
if (pmem == (void*) MAP_FAILED) {
perror("mmap");
fatal("Could not mmap physical memory!\n");
}
uint64_t curr_size = 0;
long* temp_page = new long[chunk_size];
long* pmem_current;
uint32_t bytes_read;
while (curr_size < range.size()) {
bytes_read = gzread(compressed_mem, temp_page, chunk_size);
if (bytes_read == 0)
break;
assert(bytes_read % sizeof(long) == 0);
for (uint32_t x = 0; x < bytes_read / sizeof(long); x++) {
// Only copy bytes that are non-zero, so we don't give
// the VM system hell
if (*(temp_page + x) != 0) {
pmem_current = (long*)(pmem + curr_size + x * sizeof(long));
*pmem_current = *(temp_page + x);
}
}
curr_size += bytes_read;
}
delete[] temp_page;
if (gzclose(compressed_mem))
fatal("Close failed on physical memory checkpoint file '%s'\n",
filename);
}