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From:   Ajay Kaher <akaher@vmware.com>
To:     Steven Rostedt <rostedt@goodmis.org>,
        "mhiramat@kernel.org" <mhiramat@kernel.org>,
        "shuah@kernel.org" <shuah@kernel.org>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-trace-kernel@vger.kernel.org" 
        <linux-trace-kernel@vger.kernel.org>,
        "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>,
        Ching-lin Yu <chinglinyu@google.com>,
        Nadav Amit <namit@vmware.com>,
        "srivatsa@csail.mit.edu" <srivatsa@csail.mit.edu>,
        Alexey Makhalov <amakhalov@vmware.com>,
        Vasavi Sirnapalli <vsirnapalli@vmware.com>,
        Tapas Kundu <tkundu@vmware.com>,
        "er.ajay.kaher@gmail.com" <er.ajay.kaher@gmail.com>
Subject: Re: [PATCH v3 00/10] tracing: introducing eventfs
Thread-Topic: [PATCH v3 00/10] tracing: introducing eventfs
Thread-Index: AQHZlGeSoCEyu7THQ0iKwxE3Uhr81a+Rt6wA
Date:   Mon, 19 Jun 2023 05:38:25 +0000
Message-ID: <34E6364B-2B3D-4597-8143-1EEA645B6CDD@vmware.com>
References: <1685610013-33478-1-git-send-email-akaher@vmware.com>
In-Reply-To: <1685610013-33478-1-git-send-email-akaher@vmware.com>
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> On 01-Jun-2023, at 2:30 PM, Ajay Kaher <akaher@vmware.com> wrote:
>=20
> 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.
>=20
> 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.
>=20
> Tracing events took ~9MB, with this approach it took ~4.5MB
> for ~10K files/dir.
>=20
> 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
>=20
> 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
>=20
> fs/tracefs/Makefile                           |   1 +
> fs/tracefs/event_inode.c                      | 757 ++++++++++++++++++
> fs/tracefs/inode.c                            | 124 ++-
> fs/tracefs/internal.h                         |  25 +
> include/linux/trace_events.h                  |   1 +
> include/linux/tracefs.h                       |  49 ++
> kernel/trace/trace.h                          |   3 +-
> 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, 994 insertions(+), 52 deletions(-)
> create mode 100644 fs/tracefs/event_inode.c
> create mode 100644 fs/tracefs/internal.h
>=20


Hi Steve, below is the ftracetest results with v3 of eventfs:

root@photon-6 [ ~/linux-6.3-rc5/tools/testing/selftests/ftrace ]# ./ftracet=
est
=3D=3D=3D Ftrace unit tests =3D=3D=3D
[1] Basic trace file check [PASS]
[2] Basic test for tracers [PASS]
[3] Basic trace clock test [PASS]
[4] Basic event tracing check [PASS]
[5] Change the ringbuffer size [PASS]
[6] Snapshot and tracing setting [UNSUPPORTED]
[7] trace_pipe and trace_marker [PASS]
[8] Test ftrace direct functions against tracers [UNRESOLVED]
[9] Test ftrace direct functions against kprobes [UNRESOLVED]
[10] Generic dynamic event - add/remove eprobe events [PASS]
[11] Generic dynamic event - add/remove kprobe events [PASS]
[12] Generic dynamic event - add/remove synthetic events [UNSUPPORTED]
[13] Generic dynamic event - selective clear (compatibility) [UNSUPPORTED]
[14] Event probe event parser error log check [PASS]
[15] Generic dynamic event - generic clear event [UNSUPPORTED]
[16] Generic dynamic event - check if duplicate events are caught [PASS]
[17] event tracing - enable/disable with event level files [PASS]
[18] event tracing - restricts events based on pid notrace filtering [PASS]
[19] event tracing - restricts events based on pid [PASS]
[20] event tracing - enable/disable with subsystem level files [PASS]
[21] event tracing - enable/disable with top level files [PASS]
[22] Test trace_printk from module [UNRESOLVED]
[23] event filter function - test event filtering on functions [FAIL]
[24] ftrace - function graph filters with stack tracer [UNSUPPORTED]
[25] ftrace - function graph filters [PASS]
[26] ftrace - function trace with cpumask [PASS]
[27] ftrace - test for function event triggers [PASS]
[28] ftrace - function glob filters [PASS]
[29] ftrace - function pid notrace filters [PASS]
[30] ftrace - function pid filters [PASS]
[31] ftrace - stacktrace filter command [PASS]
[32] ftrace - function trace on module [UNRESOLVED]
[33] ftrace - function profiler with function tracing [UNSUPPORTED]
[34] ftrace - function profiling [UNSUPPORTED]
[35] ftrace - test reading of set_ftrace_filter [PASS]
[36] ftrace - Max stack tracer [UNSUPPORTED]
[37] ftrace - test for function traceon/off triggers [PASS]
[38] ftrace - test tracing error log support [PASS]
[39] Test creation and deletion of trace instances while setting an event [=
PASS]
[40] Test creation and deletion of trace instances [PASS]
[41] Kprobe dynamic event - adding and removing [PASS]
[42] Kprobe dynamic event - busy event check [PASS]
[43] Kprobe event char type argument [PASS]
[44] Kprobe event with comm arguments [PASS]
[45] Kprobe event string type argument [PASS]
[46] Kprobe event symbol argument [PASS]
[47] Kprobe event argument syntax [PASS]
[48] Kprobe dynamic event with arguments [PASS]
[49] Kprobes event arguments with types [PASS]
[50] Kprobe event user-memory access [PASS]
[51] Kprobe event auto/manual naming [PASS]
[52] Kprobe dynamic event with function tracer [UNSUPPORTED]
[53] Kprobe dynamic event - probing module [UNRESOLVED]
[54] Create/delete multiprobe on kprobe event [PASS]
[55] Kprobe event parser error log check [PASS]
[56] Kretprobe dynamic event with arguments [PASS]
[57] Kretprobe dynamic event with maxactive [PASS]
[58] Kretprobe %return suffix test [PASS]
[59] Register/unregister many kprobe events [PASS]
[60] Kprobe events - probe points [FAIL]
[61] Kprobe profile [PASS]
[62] Uprobe event parser error log check [PASS]
[63] test for the preemptirqsoff tracer [UNSUPPORTED]
[64] Meta-selftest: Checkbashisms [UNRESOLVED]
[65] Test wakeup RT tracer [UNSUPPORTED]
[66] Test wakeup tracer [UNSUPPORTED]
[67] event trigger - test inter-event histogram trigger expected fail actio=
ns [UNSUPPORTED]
[68] event trigger - test field variable support [UNSUPPORTED]
[69] event trigger - test inter-event combined histogram trigger [UNSUPPORT=
ED]
[70] event trigger - test multiple actions on hist trigger [UNSUPPORTED]
[71] event trigger - test inter-event histogram trigger onchange action [UN=
SUPPORTED]
[72] event trigger - test inter-event histogram trigger onmatch action [UNS=
UPPORTED]
[73] event trigger - test inter-event histogram trigger onmatch-onmax actio=
n [UNSUPPORTED]
[74] event trigger - test inter-event histogram trigger onmax action [UNSUP=
PORTED]
[75] event trigger - test inter-event histogram trigger snapshot action [UN=
SUPPORTED]
[76] event trigger - test inter-event histogram trigger eprobe on synthetic=
 event [UNSUPPORTED]
[77] event trigger - test synthetic event create remove [UNSUPPORTED]
[78] event trigger - test inter-event histogram trigger trace action with d=
ynamic string param [UNSUPPORTED]
[79] event trigger - test inter-event histogram trigger trace action with d=
ynamic string param [UNSUPPORTED]
[80] event trigger - test synthetic_events syntax parser errors [UNSUPPORTE=
D]
[81] event trigger - test synthetic_events syntax parser [UNSUPPORTED]
[82] event trigger - test inter-event histogram trigger trace action [UNSUP=
PORTED]
[83] event trigger - test event enable/disable trigger [PASS]
[84] event trigger - test trigger filter [PASS]
[85] event trigger - test histogram expression parsing [UNSUPPORTED]
[86] event trigger - test histogram modifiers [UNSUPPORTED]
[87] event trigger - test histogram parser errors [UNSUPPORTED]
[88] event trigger - test histogram trigger [UNSUPPORTED]
[89] event trigger - test multiple histogram triggers [UNSUPPORTED]
[90] event trigger - test snapshot-trigger [UNSUPPORTED]
[91] event trigger - test stacktrace-trigger [PASS]
[92] trace_marker trigger - test histogram trigger [UNSUPPORTED]
[93] trace_marker trigger - test snapshot trigger [UNSUPPORTED]
[94] trace_marker trigger - test histogram with synthetic event against ker=
nel event [UNSUPPORTED]
[95] trace_marker trigger - test histogram with synthetic event [UNSUPPORTE=
D]
[96] event trigger - test traceon/off trigger [PASS]
[97] (instance)  Basic test for tracers [PASS]
[98] (instance)  Basic trace clock test [PASS]
[99] (instance)  Change the ringbuffer size [PASS]
[100] (instance)  Snapshot and tracing setting [UNSUPPORTED]
[101] (instance)  trace_pipe and trace_marker [PASS]
[102] (instance)  event tracing - enable/disable with event level files [PA=
SS]
[103] (instance)  event tracing - restricts events based on pid notrace fil=
tering [PASS]
[104] (instance)  event tracing - restricts events based on pid [PASS]
[105] (instance)  event tracing - enable/disable with subsystem level files=
 [PASS]
[106] (instance)  event filter function - test event filtering on functions=
 [FAIL]
[107] (instance)  ftrace - test for function event triggers [PASS]
[108] (instance)  ftrace - function pid notrace filters [PASS]
[109] (instance)  ftrace - function pid filters [PASS]
[110] (instance)  ftrace - stacktrace filter command [PASS]
[111] (instance)  ftrace - test for function traceon/off triggers [PASS]
[112] (instance)  event trigger - test event enable/disable trigger [PASS]
[113] (instance)  event trigger - test trigger filter [PASS]
[114] (instance)  event trigger - test histogram modifiers [UNSUPPORTED]
[115] (instance)  event trigger - test histogram trigger [UNSUPPORTED]
[116] (instance)  event trigger - test multiple histogram triggers [UNSUPPO=
RTED]
[117] (instance)  trace_marker trigger - test histogram trigger [UNSUPPORTE=
D]
[118] (instance)  trace_marker trigger - test snapshot trigger [UNSUPPORTED=
]


# of passed:  65
# of failed:  3
# of unresolved:  6
# of untested:  0
# of unsupported:  44
# of xfailed:  0
# of undefined(test bug):  0

These results are same with/without eventfs.

-Ajay