Skip to content

Remap thread id to avoid bitmap contention #223

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
zhengyu123 wants to merge 7 commits into from
Closed

Remap thread id to avoid bitmap contention #223

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
4bfccf5
v0
Jun 10, 2025
a9eda77
Remove unnecessary import
Jun 10, 2025
cc95793
Rename
Jun 11, 2025
bb2a116
Added assertion for potential mapped thread id overflow
Jun 11, 2025
a3d2477
Reverse lower 16 bits, instead of swapping lower 2 bytes
zhengyu123 Jun 12, 2025
0b128b5
jbachorik's comment
zhengyu123 Jun 16, 2025
463e8eb
Sign the patch
zhengyu123 Jun 17, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
Rename
  • Loading branch information
zhengyu.gu committed Jun 11, 2025
commit cc957930b34f8358cb4088310f7f56998cb04bd6
12 changes: 6 additions & 6 deletions ddprof-lib/src/main/cpp/threadFilter.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -85,21 +85,21 @@ void ThreadFilter::clear() {
_size = 0;
}

int ThreadFilter::hashThreadId(int thread_id) {
int ThreadFilter::mapThreadId(int thread_id) {
Comment thread
zhengyu123 marked this conversation as resolved.
u16 lower16 = (u16)(thread_id & 0xffff);
lower16 = ((lower16 & 0x00ff) << 8) | ((lower16 & 0xff00) >> 8);
int tid = (thread_id & ~0xffff) | lower16;
return tid;
}

bool ThreadFilter::accept(int thread_id) {
thread_id = hashThreadId(thread_id);
thread_id = mapThreadId(thread_id);
u64 *b = bitmap(thread_id);
return b != NULL && (word(b, thread_id) & (1ULL << (thread_id & 0x3f)));
}

void ThreadFilter::add(int thread_id) {
thread_id = hashThreadId(thread_id);
thread_id = mapThreadId(thread_id);
u64 *b = bitmap(thread_id);
if (b == NULL) {
b = (u64 *)OS::safeAlloc(BITMAP_SIZE);
Expand All @@ -120,7 +120,7 @@ void ThreadFilter::add(int thread_id) {
}

void ThreadFilter::remove(int thread_id) {
thread_id = hashThreadId(thread_id);
thread_id = mapThreadId(thread_id);
u64 *b = bitmap(thread_id);
if (b == NULL) {
return;
Expand All @@ -143,8 +143,8 @@ void ThreadFilter::collect(std::vector<int> &v) {
u64 word = __atomic_load_n(&b[j], __ATOMIC_ACQUIRE);
while (word != 0) {
int tid = start_id + j * 64 + __builtin_ctzl(word);
// restore thread id;
tid = hashThreadId(tid);
// restore thread id
tid = mapThreadId(tid);
v.push_back(tid);
word &= (word - 1);
}
Expand Down
2 changes: 1 addition & 1 deletion ddprof-lib/src/main/cpp/threadFilter.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ class ThreadFilter {
__ATOMIC_ACQUIRE);
}

static int hashThreadId(int thread_id);
static int mapThreadId(int thread_id);

u64 &word(u64 *bitmap, int thread_id) {
// todo: add thread safe APIs
Expand Down
Loading