[compiler-rt] [profile] Implement a non-mmap path when reading profile files from a non-local filesystem (PR #131177)
Wael Yehia via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 13 11:04:22 PDT 2025
https://github.com/w2yehia created https://github.com/llvm/llvm-project/pull/131177
… non-local filesystem
>From b817019bc77c7f19fb582e00d11331ef9556c65c Mon Sep 17 00:00:00 2001
From: Wael Yehia <wyehia at ca.ibm.com>
Date: Wed, 5 Mar 2025 14:53:24 -0500
Subject: [PATCH] [profile] Implement a non-mmap path when reading profile
files from a non-local filesystem
---
compiler-rt/lib/profile/InstrProfilingFile.c | 29 ++---
compiler-rt/lib/profile/InstrProfilingUtil.c | 116 ++++++++++++++++++
compiler-rt/lib/profile/InstrProfilingUtil.h | 19 +++
.../test/profile/Posix/instrprof-fork.c | 38 +++---
.../instrprof-no-mmap-during-merging.c | 25 ++++
5 files changed, 198 insertions(+), 29 deletions(-)
create mode 100644 compiler-rt/test/profile/instrprof-no-mmap-during-merging.c
diff --git a/compiler-rt/lib/profile/InstrProfilingFile.c b/compiler-rt/lib/profile/InstrProfilingFile.c
index e5eca7947cf9b..6d6d03476a77c 100644
--- a/compiler-rt/lib/profile/InstrProfilingFile.c
+++ b/compiler-rt/lib/profile/InstrProfilingFile.c
@@ -428,17 +428,18 @@ static int getProfileFileSizeForMerging(FILE *ProfileFile,
* \p ProfileBuffer. Returns -1 on failure. On success, the caller is
* responsible for unmapping the mmap'd buffer in \p ProfileBuffer. */
static int mmapProfileForMerging(FILE *ProfileFile, uint64_t ProfileFileSize,
- char **ProfileBuffer) {
- *ProfileBuffer = mmap(NULL, ProfileFileSize, PROT_READ, MAP_SHARED | MAP_FILE,
- fileno(ProfileFile), 0);
- if (*ProfileBuffer == MAP_FAILED) {
+ ManagedMemory *ProfileBuffer) {
+ lprofGetFileContentBuffer(ProfileFile, ProfileFileSize, ProfileBuffer);
+
+ if (ProfileBuffer->Status == MM_INVALID) {
PROF_ERR("Unable to merge profile data, mmap failed: %s\n",
strerror(errno));
return -1;
}
- if (__llvm_profile_check_compatibility(*ProfileBuffer, ProfileFileSize)) {
- (void)munmap(*ProfileBuffer, ProfileFileSize);
+ if (__llvm_profile_check_compatibility(ProfileBuffer->Addr,
+ ProfileFileSize)) {
+ (void)lprofReleaseBuffer(ProfileBuffer, ProfileFileSize);
PROF_WARN("Unable to merge profile data: %s\n",
"source profile file is not compatible.");
return -1;
@@ -453,7 +454,7 @@ static int mmapProfileForMerging(FILE *ProfileFile, uint64_t ProfileFileSize,
*/
static int doProfileMerging(FILE *ProfileFile, int *MergeDone) {
uint64_t ProfileFileSize;
- char *ProfileBuffer;
+ ManagedMemory ProfileBuffer;
/* Get the size of the profile on disk. */
if (getProfileFileSizeForMerging(ProfileFile, &ProfileFileSize) == -1)
@@ -469,9 +470,9 @@ static int doProfileMerging(FILE *ProfileFile, int *MergeDone) {
return -1;
/* Now start merging */
- if (__llvm_profile_merge_from_buffer(ProfileBuffer, ProfileFileSize)) {
+ if (__llvm_profile_merge_from_buffer(ProfileBuffer.Addr, ProfileFileSize)) {
PROF_ERR("%s\n", "Invalid profile data to merge");
- (void)munmap(ProfileBuffer, ProfileFileSize);
+ (void)lprofReleaseBuffer(&ProfileBuffer, ProfileFileSize);
return -1;
}
@@ -480,7 +481,7 @@ static int doProfileMerging(FILE *ProfileFile, int *MergeDone) {
(void)COMPILER_RT_FTRUNCATE(ProfileFile,
__llvm_profile_get_size_for_buffer());
- (void)munmap(ProfileBuffer, ProfileFileSize);
+ (void)lprofReleaseBuffer(&ProfileBuffer, ProfileFileSize);
*MergeDone = 1;
return 0;
@@ -702,13 +703,13 @@ static void initializeProfileForContinuousMode(void) {
} else {
/* The merged profile has a non-zero length. Check that it is compatible
* with the data in this process. */
- char *ProfileBuffer;
+ ManagedMemory ProfileBuffer;
if (mmapProfileForMerging(File, ProfileFileSize, &ProfileBuffer) == -1) {
lprofUnlockFileHandle(File);
fclose(File);
return;
}
- (void)munmap(ProfileBuffer, ProfileFileSize);
+ (void)lprofReleaseBuffer(&ProfileBuffer, ProfileFileSize);
}
} else {
File = fopen(Filename, FileOpenMode);
@@ -1346,12 +1347,12 @@ COMPILER_RT_VISIBILITY int __llvm_profile_set_file_object(FILE *File,
} else {
/* The merged profile has a non-zero length. Check that it is compatible
* with the data in this process. */
- char *ProfileBuffer;
+ ManagedMemory ProfileBuffer;
if (mmapProfileForMerging(File, ProfileFileSize, &ProfileBuffer) == -1) {
lprofUnlockFileHandle(File);
return 1;
}
- (void)munmap(ProfileBuffer, ProfileFileSize);
+ (void)lprofReleaseBuffer(&ProfileBuffer, ProfileFileSize);
}
mmapForContinuousMode(0, File);
lprofUnlockFileHandle(File);
diff --git a/compiler-rt/lib/profile/InstrProfilingUtil.c b/compiler-rt/lib/profile/InstrProfilingUtil.c
index c637b9d0b893c..4bec5feca823f 100644
--- a/compiler-rt/lib/profile/InstrProfilingUtil.c
+++ b/compiler-rt/lib/profile/InstrProfilingUtil.c
@@ -21,6 +21,15 @@
#include <unistd.h>
#endif
+#ifdef _AIX
+#include <sys/statfs.h>
+// <sys/vmount.h> depends on `uint` to be a typedef from <sys/types.h> to
+// `uint_t`; however, <sys/types.h> does not always declare `uint`. We provide
+// the typedef prior to including <sys/vmount.h> to work around this issue.
+typedef uint_t uint;
+#include <sys/vmount.h>
+#endif
+
#ifdef COMPILER_RT_HAS_UNAME
#include <sys/utsname.h>
#endif
@@ -258,6 +267,113 @@ COMPILER_RT_VISIBILITY FILE *lprofOpenFileEx(const char *ProfileName) {
return f;
}
+// Return 1 (true) if the file descriptor Fd represents a file that is on a
+// local filesystem, otherwise return 0.
+static int is_local_filesystem(int Fd) {
+#if defined(_AIX)
+ struct statfs Vfs;
+ if (fstatfs(Fd, &Vfs) != 0) {
+ PROF_ERR("%s: fstatfs(%d) failed: %s\n", __func__, Fd, strerror(errno));
+ return 0;
+ }
+
+ int Ret;
+ size_t BufSize = 2048u;
+ char *Buf;
+ int Tries = 3;
+ while (Tries--) {
+ Buf = malloc(BufSize);
+ Ret = mntctl(MCTL_QUERY, BufSize, Buf);
+ if (Ret != 0)
+ break;
+ BufSize = *(unsigned int *)Buf;
+ free(Buf);
+ }
+
+ if (Ret != -1) {
+ // Look for the correct vmount entry.
+ char *CurObjPtr = Buf;
+ while (Ret--) {
+ struct vmount *Vp = (struct vmount *)CurObjPtr;
+ _Static_assert(sizeof(Vfs.f_fsid) == sizeof(Vp->vmt_fsid),
+ "fsid length mismatch");
+ if (memcmp(&Vfs.f_fsid, &Vp->vmt_fsid, sizeof Vfs.f_fsid) == 0) {
+ free(Buf);
+ return (Vp->vmt_flags & MNT_REMOTE) == 0;
+ }
+ CurObjPtr += Vp->vmt_length;
+ }
+ }
+
+ free(Buf);
+ // There was an error in mntctl or vmount entry not found; "remote" is the
+ // conservative answer.
+#endif
+ return 0;
+}
+
+static int isMmapSafe(int Fd) {
+ if (getenv("LLVM_NO_MMAP")) // For testing purposes.
+ return 0;
+ (void)&is_local_filesystem; // a fake reference to satisfy -Wunused-function
+#ifdef _AIX
+ return is_local_filesystem(Fd);
+#endif
+ return 1;
+}
+
+COMPILER_RT_VISIBILITY void lprofGetFileContentBuffer(FILE *F, uint64_t Length,
+ ManagedMemory *Buf) {
+ Buf->Status = MM_INVALID;
+
+ if (!F || isMmapSafe(fileno(F))) {
+ Buf->Addr = mmap(NULL, Length, PROT_READ, MAP_SHARED | MAP_FILE,
+ F ? fileno(F) : -1, 0);
+ if (Buf->Addr != MAP_FAILED)
+ Buf->Status = MM_MMAP;
+ return;
+ }
+
+ if (getenv("LLVM_PROFILE_VERBOSE"))
+ PROF_NOTE("Could not use mmap; using fread instead.%s\n", "");
+
+ void *Buffer = malloc(Length);
+
+ if (!Buffer) {
+ PROF_ERR("%s: malloc failed: %s\n", __func__, strerror(errno));
+ return;
+ }
+ if (fseek(F, 0L, SEEK_SET) != 0) {
+ PROF_ERR("%s: fseek(0, SEEK_SET) failed: %s\n", __func__, strerror(errno));
+ return;
+ }
+
+ // Read the entire file into memory.
+ size_t BytesRead = fread(Buffer, 1, Length, F);
+ if (BytesRead != (size_t)Length || ferror(F)) {
+ PROF_ERR("%s: fread failed: %s\n", __func__, strerror(errno));
+ return;
+ }
+
+ // Reading was successful, record the result in the Buf parameter.
+ Buf->Addr = Buffer;
+ Buf->Status = MM_MALLOC;
+}
+
+void lprofReleaseBuffer(ManagedMemory *Buf, size_t Length) {
+ switch (Buf->Status) {
+ case MM_MALLOC:
+ free(Buf->Addr);
+ break;
+ case MM_MMAP:
+ munmap(Buf->Addr, Length);
+ break;
+ case MM_INVALID:
+ PROF_ERR("%s: Buffer has invalid state: %d", __func__, Buf->Status);
+ break;
+ }
+}
+
COMPILER_RT_VISIBILITY const char *lprofGetPathPrefix(int *PrefixStrip,
size_t *PrefixLen) {
const char *Prefix = getenv("GCOV_PREFIX");
diff --git a/compiler-rt/lib/profile/InstrProfilingUtil.h b/compiler-rt/lib/profile/InstrProfilingUtil.h
index 227c2aa0a7cae..9a7550aad9fab 100644
--- a/compiler-rt/lib/profile/InstrProfilingUtil.h
+++ b/compiler-rt/lib/profile/InstrProfilingUtil.h
@@ -31,6 +31,25 @@ int lprofUnlockFileHandle(FILE *F);
* lock for exclusive access. The caller will block
* if the lock is already held by another process. */
FILE *lprofOpenFileEx(const char *Filename);
+
+enum MemoryStatus {
+ MM_INVALID = 0x1, // Addr is not a valid address
+ MM_MMAP = 0x2, // Addr was mmap'ed
+ MM_MALLOC = 0x4 // Addr was malloc'ed
+};
+typedef struct {
+ void *Addr;
+ enum MemoryStatus Status;
+} ManagedMemory;
+
+/* Read the content of a file using mmap or fread into a buffer.
+ * Certain files (e.g. NFS mounted) cannot be opened reliably with mmap,
+ * so we use fread in those cases. The corresponding lprofReleaseBuffer
+ * will free/munmap the buffer.
+ */
+void lprofGetFileContentBuffer(FILE *F, uint64_t FileSize, ManagedMemory *Buf);
+void lprofReleaseBuffer(ManagedMemory *FileBuffer, size_t Length);
+
/* PS4 doesn't have setenv/getenv/fork. Define a shim. */
#if __ORBIS__
#include <sys/types.h>
diff --git a/compiler-rt/test/profile/Posix/instrprof-fork.c b/compiler-rt/test/profile/Posix/instrprof-fork.c
index 8df0abd73c4c3..6724efa30a2f6 100644
--- a/compiler-rt/test/profile/Posix/instrprof-fork.c
+++ b/compiler-rt/test/profile/Posix/instrprof-fork.c
@@ -3,11 +3,15 @@
// RUN: %clang_pgogen=%t.profdir -o %t -O2 %s
// RUN: %run %t
// RUN: llvm-profdata show --all-functions --counts %t.profdir/default_*.profraw | FileCheck %s
+// RUN: rm -fr %t.profdir
+// RUN: env LLVM_NO_MMAP=1 %run %t
+// RUN: llvm-profdata show --all-functions --counts %t.profdir/default_*.profraw | FileCheck %s
+
//
// CHECK: func1:
-// CHECK: Block counts: [4]
+// CHECK: Block counts: [21]
// CHECK: func2:
-// CHECK: Block counts: [1]
+// CHECK: Block counts: [10]
#include <sys/wait.h>
#include <unistd.h>
@@ -16,17 +20,21 @@ __attribute__((noinline)) void func1() {}
__attribute__((noinline)) void func2() {}
int main(void) {
- // child | parent
- int status; // func1 func2 | func1 func2
- func1(); // +1 | +1 (*)
- pid_t pid = fork(); // |
- if (pid == -1) // |
- return 1; // |
- if (pid == 0) // |
- func2(); // +1 |
- func1(); // +1 | +1
- if (pid) // ------------+------------
- wait(&status); // 2 1 | 2 0
- return 0; // (*) the child inherits counter values prior to fork
- // from the parent in non-continuous mode.
+ // child | parent
+ // func1 func2 | func1 func2
+ func1(); // +10 | +1 (*)
+ int i = 10; // |
+ while (i-- > 0) { // |
+ pid_t pid = fork(); // |
+ if (pid == -1) // |
+ return 1; // |
+ if (pid == 0) { // |
+ func2(); // +10 |
+ func1(); // +10 |
+ return 0; // |
+ } // |
+ } // ------------+------------
+ int status; // 20 10 | 1 0
+ wait(&status); // (*) the child inherits counter values prior to fork
+ return 0; // from the parent in non-continuous mode.
}
diff --git a/compiler-rt/test/profile/instrprof-no-mmap-during-merging.c b/compiler-rt/test/profile/instrprof-no-mmap-during-merging.c
new file mode 100644
index 0000000000000..ee74b158a78a4
--- /dev/null
+++ b/compiler-rt/test/profile/instrprof-no-mmap-during-merging.c
@@ -0,0 +1,25 @@
+// RUN: mkdir -p %t.d && cd %t.d
+// RUN: rm -f *.profraw
+// RUN: %clang_pgogen %s -o a.out
+
+// Need to run a.out twice, the second time a merge will occur which will trigger an mmap.
+// RUN: ./a.out
+// RUN: llvm-profdata show default_*.profraw --all-functions --counts --memop-sizes 2>&1 | FileCheck %s -check-prefix=PROFDATA
+// RUN: env LLVM_NO_MMAP=1 LLVM_PROFILE_VERBOSE=1 ./a.out 2>&1 | FileCheck %s
+// RUN: llvm-profdata show default_*.profraw --all-functions --counts --memop-sizes 2>&1 | FileCheck %s -check-prefix=PROFDATA2
+
+// CHECK: Could not use mmap; using fread instead.
+// PROFDATA: Block counts: [1]
+// PROFDATA: [ 0, 0, 1 ]
+// PROFDATA: Maximum function count: 1
+// PROFDATA2: Block counts: [2]
+// PROFDATA2: [ 0, 0, 2 ]
+// PROFDATA2: Maximum function count: 2
+
+#include <string.h>
+int ar[8];
+int main() {
+ memcpy(ar, ar + 2, ar[0]);
+ memcpy(ar, ar + 2, ar[2]);
+ return ar[2];
+}
More information about the llvm-commits
mailing list