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[ports, freebsd] use shm_create_largepage(3) with a DEFAULT allocation to exploit defragmented RAM situations

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Signed-off-by: lizzie <lizzie@eden-emu.dev>
This commit is contained in:
lizzie 2026-04-26 09:39:11 +00:00
parent 91058d7383
commit 731e468f31
1 changed files with 31 additions and 0 deletions
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31
src/common/host_memory.cpp
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@ -22,6 +22,7 @@
#include <sys/mman.h>
#include <unistd.h>
#include "common/scope_exit.h"
#include "common/literals.h"
#if defined(__linux__)
#include <sys/random.h>
@ -506,7 +507,32 @@ public:
#elif defined(__OpenBSD__)
fd = shm_open_anon(O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW, 0600);
#elif defined(__FreeBSD__)
int n_page_sizes = getpagesizes(nullptr, 0);
if (n_page_sizes > 0) {
std::vector<size_t> page_sizes(n_page_sizes);
if (getpagesizes(page_sizes.data(), n_page_sizes) > 0) {
size_t max_size = page_sizes[0];
size_t max_index = 0;
for (size_t i = 0; i < page_sizes.size(); ++i) {
using namespace Common::Literals;
if (page_sizes[i] <= 4_GiB) {
max_size = (std::max)(max_size, page_sizes[i]);
max_index = i;
}
}
LOG_WARNING(Common_Memory, "using largepage of size {} #{}", max_size, max_index);
// Do not use SHM_LARGEPAGE_ALLOC_HARD, yknow what will happen when you do?
// the entire Eden process will hang for eternity! that's what will happen
// Want to fuck around and find out? Go ahead, I tempt you change the "default" to "hard"
fd = shm_create_largepage(SHM_ANON, O_RDWR, max_index, SHM_LARGEPAGE_ALLOC_DEFAULT, 0600);
}
}
if (fd >= 0) {
} else {
LOG_WARNING(Common_Memory, "unable to force largepage: {}", strerror(errno));
fd = shm_open(SHM_ANON, O_RDWR, 0600);
}
#elif defined(__APPLE__)
// macOS doesn't have memfd_create, use anonymous temporary file
char template_path[] = "/tmp/eden_mem_XXXXXX";
@ -538,7 +564,12 @@ public:
close(fd);
}
} else {
#ifdef __FreeBSD__
// Prevent dirty tracking of memfd
backing_base = static_cast<u8*>(mmap(nullptr, backing_size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_NOSYNC, fd, 0));
#else
backing_base = static_cast<u8*>(mmap(nullptr, backing_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
#endif
}
ASSERT_MSG(backing_base != MAP_FAILED, "mmap failed: {}", strerror(errno));