Events Tracing infrastructure contains lot of files, directories (internally in terms of inodes, dentries). And ends up by consuming memory in MBs. We can have multiple events of Events Tracing, which further requires more memory.
Instead of creating inodes/dentries, eventfs could keep meta-data and skip the creation of inodes/dentries. As and when require, eventfs will create the inodes/dentries only for required files/directories. Also eventfs would delete the inodes/dentries once no more requires but preserve the meta data.
Tracing events took ~9MB, with this approach it took ~4.5MB for ~10K files/dir.
v3: Patch 3,4,5,7,9: removed all the eventfs_rwsem code and replaced it with an srcu lock for the readers, and a mutex to synchronize the writers of the list.
Patch 2: moved 'tracefs_inode' and 'get_tracefs()' to v4 03/10
Patch 3: moved the struct eventfs_file and eventfs_inode into event_inode.c as it really should not be exposed to all users.
Patch 5: added a recursion check to eventfs_remove_rec() as it is really dangerous to have unchecked recursion in the kernel (we do have a fixed size stack).
have the free use srcu callbacks. After the srcu grace periods are done, it adds the eventfs_file onto a llist (lockless link list) and wakes up a work queue. Then the work queue does the freeing (this needs to be done in task/workqueue context, as srcu callbacks are done in softirq context).
Patch 6: renamed: eventfs_create_file() -> create_file() eventfs_create_dir() -> create_dir()
v2: Patch 01: new patch:'Require all trace events to have a TRACE_SYSTEM' Patch 02: moved from v1 1/9 Patch 03: moved from v1 2/9 As suggested by Zheng Yejian, introduced eventfs_prepare_ef() helper function to add files or directories to eventfs fix WARNING reported by kernel test robot in v1 8/9 Patch 04: moved from v1 3/9 used eventfs_prepare_ef() to add files fix WARNING reported by kernel test robot in v1 8/9 Patch 05: moved from v1 4/9 fix compiling warning reported by kernel test robot in v1 4/9 Patch 06: moved from v1 5/9 Patch 07: moved from v1 6/9 Patch 08: moved from v1 7/9 Patch 09: moved from v1 8/9 rebased because of v3 01/10 Patch 10: moved from v1 9/9
v1: Patch 1: add header file Patch 2: resolved kernel test robot issues protecting eventfs lists using nested eventfs_rwsem Patch 3: protecting eventfs lists using nested eventfs_rwsem Patch 4: improve events cleanup code to fix crashes Patch 5: resolved kernel test robot issues removed d_instantiate_anon() calls Patch 6: resolved kernel test robot issues fix kprobe test in eventfs_root_lookup() protecting eventfs lists using nested eventfs_rwsem Patch 7: remove header file Patch 8: pass eventfs_rwsem as argument to eventfs functions called eventfs_remove_events_dir() instead of tracefs_remove() from event_trace_del_tracer() Patch 9: new patch to fix kprobe test case
Ajay Kaher (9): tracefs: Rename some tracefs function eventfs: Implement eventfs dir creation functions eventfs: Implement eventfs file add functions eventfs: Implement eventfs file, directory remove function eventfs: Implement functions to create eventfs files and directories eventfs: Implement eventfs lookup, read, open functions eventfs: Implement tracefs_inode_cache eventfs: Move tracing/events to eventfs test: ftrace: Fix kprobe test for eventfs
Steven Rostedt (Google) (1): tracing: Require all trace events to have a TRACE_SYSTEM
fs/tracefs/Makefile | 1 + fs/tracefs/event_inode.c | 711 ++++++++++++++++++ fs/tracefs/inode.c | 124 ++- fs/tracefs/internal.h | 25 + include/linux/trace_events.h | 1 + include/linux/tracefs.h | 32 + kernel/trace/trace.h | 2 +- kernel/trace/trace_events.c | 78 +- .../ftrace/test.d/kprobe/kprobe_args_char.tc | 4 +- .../test.d/kprobe/kprobe_args_string.tc | 4 +- 10 files changed, 930 insertions(+), 52 deletions(-) create mode 100644 fs/tracefs/event_inode.c create mode 100644 fs/tracefs/internal.h