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Sat, 22 Jul 2023 19:38:05 +0000 From: Ajay Kaher To: rostedt@goodmis.org, shuah@kernel.org, mhiramat@kernel.org Cc: chinglinyu@google.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-kernel@vger.kernel.org, lkp@intel.com, namit@vmware.com, oe-lkp@lists.linux.dev, akaher@vmware.com, amakhalov@vmware.com, er.ajay.kaher@gmail.com, srivatsa@csail.mit.edu, tkundu@vmware.com, vsirnapalli@vmware.com Subject: [PATCH v5 00/10] tracing: introducing eventfs Date: Sun, 23 Jul 2023 01:06:55 +0530 Message-Id: <1690054625-31939-1-git-send-email-akaher@vmware.com> X-Mailer: git-send-email 2.7.4 X-ClientProxiedBy: BY5PR20CA0009.namprd20.prod.outlook.com (2603:10b6:a03:1f4::22) To PH0PR05MB8703.namprd05.prod.outlook.com (2603:10b6:510:bd::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH0PR05MB8703:EE_|MN0PR05MB9005:EE_ X-MS-Office365-Filtering-Correlation-Id: 6d231707-8548-4ac5-bf77-08db8aeb2b67 X-LD-Processed: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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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. Diff from v4: Patch 02: moved from v4 08/10 added fs/tracefs/internal.h Patch 03: moved from v4 02/10 removed fs/tracefs/internal.h Patch 04: moved from v4 03/10 moved out changes of fs/tracefs/internal.h Patch 05: moved from v4 04/10 renamed eventfs_add_top_file() -> eventfs_add_events_file() Patch 06: moved from v4 07/10 implemented create_dentry() helper function added create_file(), create_dir() stub function Patch 07: moved from v4 06/10 Patch 08: moved from v4 05/10 improved eventfs remove functionality Patch 09: removed unwanted if conditions Patch 10: added available_filter_functions check Diff from 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() Diff from 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 Diff from 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 fs/tracefs/Makefile | 1 + fs/tracefs/event_inode.c | 795 ++++++++++++++++++ fs/tracefs/inode.c | 151 +++- fs/tracefs/internal.h | 26 + include/linux/trace_events.h | 1 + include/linux/tracefs.h | 30 + kernel/trace/trace.h | 2 +- kernel/trace/trace_events.c | 76 +- .../ftrace/test.d/kprobe/kprobe_args_char.tc | 9 +- .../test.d/kprobe/kprobe_args_string.tc | 9 +- 10 files changed, 1048 insertions(+), 52 deletions(-) create mode 100644 fs/tracefs/event_inode.c create mode 100644 fs/tracefs/internal.h