Em Mon, Mar 13, 2023 at 01:48:21PM -0700, Namhyung Kim escreveu: > Hello, > > This patchset improves the symbolization of locks for -l/--lock-addr mode. > As of now it only shows global lock symbols present in the kallsyms. But > we can add some more lock symbols by traversing pointers in the BPF program. > > For example, mmap_lock can be reached from the mm_struct of the current task > (task_struct->mm->mmap_lock) and we can compare the address of the give lock > with it. Similarly I've added 'siglock' for current->sighand->siglock. > > On the other hand, we can traverse some of semi-global locks like per-cpu, > per-device, per-filesystem and so on. I've added 'rqlock' for each cpu's > runqueue lock. > > It cannot cover all types of locks in the system but it'd be fairly usefule > if we can add many of often contended locks. I tried to add futex locks > but it failed to find the __futex_data symbol from BTF. I'm not sure why but > I guess it's because the struct doesn't have a tag name. > > Those locks are added just because they got caught during my test. > It'd be nice if you suggest which locks to add and how to do that. :) > I'm thinking if there's a way to track file-based locks (like epoll, etc). > > Finally I also added a lock type name after the symbols (if any) so that we > can get some idea even though it has no symbol. The example output looks > like below: > > $ sudo ./perf lock con -abl -- sleep 1 > contended total wait max wait avg wait address symbol > > 44 6.13 ms 284.49 us 139.28 us ffffffff92e06080 tasklist_lock (rwlock) > 159 983.38 us 12.38 us 6.18 us ffff8cc717c90000 siglock (spinlock) > 10 679.90 us 153.35 us 67.99 us ffff8cdc2872aaf8 mmap_lock (rwsem) > 9 558.11 us 180.67 us 62.01 us ffff8cd647914038 mmap_lock (rwsem) > 78 228.56 us 7.82 us 2.93 us ffff8cc700061c00 (spinlock) > 5 41.60 us 16.93 us 8.32 us ffffd853acb41468 (spinlock) > 10 37.24 us 5.87 us 3.72 us ffff8cd560b5c200 siglock (spinlock) > 4 11.17 us 3.97 us 2.79 us ffff8d053ddf0c80 rq_lock (spinlock) > 1 7.86 us 7.86 us 7.86 us ffff8cd64791404c (spinlock) > 1 4.13 us 4.13 us 4.13 us ffff8d053d930c80 rq_lock (spinlock) > 7 3.98 us 1.67 us 568 ns ffff8ccb92479440 (mutex) > 2 2.62 us 2.33 us 1.31 us ffff8cc702e6ede0 (rwlock) > > The tasklist_lock is global so it's from the kallsyms. But others like > siglock, mmap_lock and rq_lock are from the BPF. Beautiful :-) And the csets are _so_ small and demonstrate techniques that should be used in more and more tools. Applied, testing. - Arnaldo > You get get the code at 'perf/lock-symbol-v1' branch in > > git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > Thanks, > Namhyung > > Namhyung Kim (4): > perf lock contention: Track and show mmap_lock with address > perf lock contention: Track and show siglock with address > perf lock contention: Show per-cpu rq_lock with address > perf lock contention: Show lock type with address > > tools/perf/builtin-lock.c | 46 +++++++---- > tools/perf/util/bpf_lock_contention.c | 35 ++++++++- > .../perf/util/bpf_skel/lock_contention.bpf.c | 77 +++++++++++++++++++ > tools/perf/util/bpf_skel/lock_data.h | 14 ++++ > 4 files changed, 152 insertions(+), 20 deletions(-) > > > base-commit: b8fa3e3833c14151a47ebebbc5427dcfe94bb407 > -- > 2.40.0.rc1.284.g88254d51c5-goog > -- - Arnaldo
