Hi Carsten,
Sorry for late response.
On Thu, Apr 21, 2022 at 06:38:33PM +0100, Carsten Haitzler wrote:
[...]
Very big change... Why squash all patches form previous verion to this
single one big patch? Usually the format with small patches is much
better for reviewing.
I was asked to re-jig the tree and in doing so I also ended up cutting down
the size a lot so this just makes more sense together as a "here are the
tests" as adding infra without any tests makes no sense and the tests
themelves are self-contained in their own directories and source files and
"drivign scripts" thus it's essentially patch 1 appended to patch 2 to patch
3 etc. and still broken up in the patch file by file.
I am not sure if I understand the meaning, seems to me you could
organize the patch series like:
- Patch for common files (e.g. script lib/coresight.sh or some
Makefile changes);
- Patches for enabling test cases, E.g.:
patch for asm_pure_loop;
patch for thread loop (include unroll loop);
patch for memcpy;
- Patch for documentation.
If this is not comfortable for you, at least we can use three patches:
- Patch for common file (e.g. script lib/coresight.sh);
- Patch for test cases;
- Patch for documentation.
[...]
+If you see these above, then your system is tracing coresight data
+correctly.
+
+To compile perf with coresight support in the perf directory do
+
+ make CORESIGHT=1
It is inaccurate that if we don't mention openCSD lib.
Do you mean I need to mention that you need the opencsd library installed
too?
Yes, otherwise, users might directly build perf without opencsd lib,
then finally they cannot use perf with Arm CoreSight.
+This will compile the perf tool with coresight support as well as
+build some small test binaries for perf test. This requires you also
+be compiling for 64bit Arm (ARM64/aarch64). The tools run as part of
+perf coresight tracing are in tests/shell/tools/coresight.
For build perf tool, I think above paragraphs are duplicate with the
document Documentation/trace/coresight/coresight.rst. Can we simply
say:
"The details for building perf tool with support Arm Coresight can be
found in the "HOWTO.md" file of the openCSD gitHub repository:
https://github.com/Linaro/opencsd.
I can. I put this here as I didn't go clone OpencCSD first but used my
distro OpenCSD packages and thus of course didn't have the documentation in
front of me. I spent some time wondering why it wasn't building with
coresight support even though it detected OpenCSD when I compiled... I
didn't expect to have to go to some separate project git repository and read
docs there on how to build the perf tool here in the kernel. I wrote this
because it was an actual problem I hit and it's a lot less frustrating to
"end users" to give them the information they need in the relevant place
they need it instead of sending them around to other project trees. Building
perf with coresight support is handled by the perf tree int he kernel, not
OpenCSD, thus IMHO that is where the documentation belongs - alongside the
thing that determines how to build something.
Understand.
And "HOWTO.md" file gives the information and examples for how to use
perf tool to record and report Coresight trace data. It's the
prerequisite for this perf Coresight test."
+You will also want coresight support enabled in your kernel config.
+Ensure it is enabled with:
+
+ CONFIG_CORESIGHT=y
+
+There are various other coresight options you probably also want
+enabled like:
+
+ CONFIG_CORESIGHT_LINKS_AND_SINKS=y
+ CONFIG_CORESIGHT_LINK_AND_SINK_TMC=y
+ CONFIG_CORESIGHT_CATU=y
+ CONFIG_CORESIGHT_SINK_TPIU=y
+ CONFIG_CORESIGHT_SINK_ETBV10=y
+ CONFIG_CORESIGHT_SOURCE_ETM4X=y
+ CONFIG_CORESIGHT_STM=y
+ CONFIG_CORESIGHT_CPU_DEBUG=y
+ CONFIG_CORESIGHT_CTI=y
+ CONFIG_CORESIGHT_CTI_INTEGRATION_REGS=y
+
+Please refer to the kernel configuration help for more information.
I prefer to remove these kernel configuration since they are not
inconsistent on different platforms (e.g. ETBV10, ETM4X, etc), and
some configurations might not necessary (e.g. CPU_DEBUG).
Certainly there should be some documentation on which kernel configs you
might want to turn on then? Imagine someone new comes along and doesn't have
any idea what to possible enable at all and manages to build perf with
coresight support (as above) then finds it doesn't work because they didn't
enable enough config in the kernel? Sure - could probably trim these down a
bit but the point here is to alert the user to there being a range of
coresight config options that you need to turn on that you likely will find
are not turned on. They certainly are not turned on on distro kernels and a
lot of the time when you have a platform that already boots/works you start
with your distro kernel config file because you want everything enabled so
it actually boots. I've learned the hard way to do this as you manage to
forget to turn on some MMC driver or some other feature and your boot hangs
or doesn't find rootfs etc.
So far, we will have two documents in Linux kernel:
- Documentation/trace/coresight/coresight.rst;
- tools/perf/Documentation/arm-coresight.txt.
We need to avoid overlap between these two files. I think we could use
the file Documentation/trace/coresight/coresight.rst to focus on
CoreSight driver module relates stuffs and
tools/perf/Documentation/arm-coresight.txt is more about the perf
usages.
But, the file Documentation/trace/coresight/coresight.rst doesn't give
any info for kernel configs, I think which would be a better place to
give information for building kernel modules.
What would you recommend then as a "turn these on and coresight will almost
certainly work for you on your given hardware " then?
This would be fine. Alternatively, we could add a section in the file
Documentation/trace/coresight/coresight.rst to describe how to build
CoreSight modules.
How you think for this? I also would like to get suggestions from
CoreSight maintainers Suzuki/Mathieu/Mike.
[...]
Please update based on the latest test case names, at my side, I can
see the testing case like:
Coresight / ASM Pure Loop
Coresight / Memcpy 16k 10 Threads
Coresight / Thread Loop 10 Threads - Check TID
Coresight / Thread Loop 2 Threads - Check TID
Coresight / Unroll Loop Thread 10
Oh sorry - yeah. I wrote the docs based on the earlier tests. Will fix.
Thanks.
+
+These perf record tests will not run if the tool binaries do not exist
+in tests/shell/tools/coresight/*/ and will be skipped. If you do not
+have coresight support in hardware then either do not build perf with
+coresight support or remove these binaries in order to not have these
+tests fail and have them skip instead.
+
+These tests will log historical results in the current working
+directory (e.g. tools/perf) and will be named stats-*.csv like:
+
+ stats-asm_pure_loop-out.csv
+ stats-bubble_sort-random.csv
+ ...
+
+These statistic files log some aspects of the AUX data sections in
+the perf data output counting some numbers of certain encodings (a
+good way to know that it's working in a very simple way). One problem
+with coresight is that given a large enough amount of data needing to
+be logged, some of it can be lost due to the processor not waking up
+in time to read out all the data from buffers etc.. You will notice
+that the amount of data collected can vary a lot per run of perf test.
+If you wish to see how this changes over time, simply run perf test
+multiple times and all these csv files will have more and more data
+appended to it that you can later examine, graph and otherwise use to
+figure out if things have become worse or better.
I am confused by this narrative. Does it try to remind that the final
testing result (pass or fail) is not stable? Or should we run for
multiple times so have more chance to capture issues?
That is correct. I thought I was clear that it's lossy. That is actually the
case. I have tests here that actually fail because there is no data
collected from some threads at all (missing CID blocks for some of the
threads that run in the test). The point is to have tests that may be
failing now but in future will improve. I lowered the minimum bar to pass
for most tests to have "at least just a little data" but most tests show
highly variable amount of captured data. the csv files are there to
over-time give you a good idea of the stability of the captured data.
Okay, this would be fine for me. Though I am a bit worry that later if
users report a failure, then how we can tell them this is a bug or it's
just tracing quality issue?
[...]
diff --git a/tools/perf/tests/shell/coresight/asm_pure_loop/.gitignore b/tools/perf/tests/shell/coresight/asm_pure_loop/.gitignore
new file mode 100644
index 000000000000..468673ac32e8
--- /dev/null
+++ b/tools/perf/tests/shell/coresight/asm_pure_loop/.gitignore
@@ -0,0 +1 @@
+asm_pure_loop
Do we really need there '.gitignore' files under the folder
'tools/perf/tests/shell/coresight/'.
Where would you rather have them to ignore the generated binary tools?
It's interesting that I wanted to find a case to object you, so I tried
to check the folder linux/samples/bpf, but it does use .gitignore file
to ignore built binaries :)
Adding .gitignore is in practice and this would be fine for me.
diff --git a/tools/perf/tests/shell/coresight/asm_pure_loop/Makefile b/tools/perf/tests/shell/coresight/asm_pure_loop/Makefile
new file mode 100644
index 000000000000..10c5a60cb71c
--- /dev/null
+++ b/tools/perf/tests/shell/coresight/asm_pure_loop/Makefile
@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: GPL-2.0
+# Carsten Haitzler <carsten.haitzler@xxxxxxx>, 2021
+
+include ../Makefile.miniconfig
+
+BIN=asm_pure_loop
+LIB=
Remove the unused variable 'LIB='.
I have this because I wanted to have a simple template to be able to re-use
for more tests over time. It's so much easier to maintain and extend if
every makefile and tool follow a similar pattern and you can almost copy &
paste between them as they don't have "exceptions". You really want me to
remove this?
It's fine to keep it. Could you add a comment for this?
To be honest, I am not experienced for bash shell script, so I have no
idea why write like this way. If you think this is very common usage
in shell, then you could keep it and don't need to add comment.
[...]
There have four sub folders under tools/perf/tests/shell/coresight:
asm_pure_loop
memcpy_thread
thread_loop
unroll_loop_thread
And every folder has its own Makefile and every Makefile is quite
close to each other. I am just wandering if it's possible to
remove the 4 Makefiles in these four sub folders, and simply use
tools/perf/tests/shell/coresight/Makefile as the central place to
build these assistant programs.
I did this so it's easier to etxent over time. having a single parent
makefile that over time accumulates little ugly "if's" and exceptions makes
longer-term maintenance and extending harder. I did it this way to make this
easy - make a copy of a dir - add that dir to a parent makefile then modify
the makefile as needed (but only as needed).
Okay, let's keep the saperate makefiles.
diff --git a/tools/perf/tests/shell/coresight/asm_pure_loop/asm_pure_loop.S b/tools/perf/tests/shell/coresight/asm_pure_loop/asm_pure_loop.S
new file mode 100644
index 000000000000..75cf084a927d
--- /dev/null
+++ b/tools/perf/tests/shell/coresight/asm_pure_loop/asm_pure_loop.S
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Tamas Zsoldos <tamas.zsoldos@xxxxxxx>, 2021 */
+
+.globl _start
+_start:
+ mov x0, 0x0000ffff
+ mov x1, xzr
+loop:
+ nop
+ nop
+ cbnz x1, noskip
+ nop
+ nop
+ adrp x2, skip
+ add x2, x2, :lo12:skip
+ br x2
+ nop
+ nop
+noskip:
+ nop
+ nop
+skip:
+ sub x0, x0, 1
+ cbnz x0, loop
+
+ mov x0, #0
+ mov x8, #93 // __NR_exit syscall
+ svc #0
I tested the case "ASM Pure Loop" on my Juno board, and it complaints:
root@debian:/mnt/export/arm-linux-kernel/tools/perf# ./perf test -v 76
76: Coresight / ASM Pure Loop :
--- start ---
test child forked, pid 9063
failed to mmap with 12 (Cannot allocate memory)
test child finished with -1
---- end ----
Coresight / ASM Pure Loop: FAILED!
Since I only setup the 1GB memory for the Linux kernel, it fails to
allocate AUX ring buffer with the size 256MB. So I manully change
the buffer size to 8MB in tools/perf/tests/shell/lib/coresight.sh:
PERFRECMEM="-m ,8M"
So finally I can see the test case is passed:
This is artificial isn't it? limiting to 1GB. You certainly have far more
memory than that available. My testse were on a system with 4GB and I had no
issues.
Please see below comment.
root@debian:/mnt/export/arm-linux-kernel/tools/perf# ./perf test -v 76
76: Coresight / ASM Pure Loop :
--- start ---
test child forked, pid 9481
-m ,8M -e cs_etm//u
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.681 MB ./perf-asm_pure_loop-out.data ]
test child finished with 0
---- end ----
Coresight / ASM Pure Loop: Ok
Do you think we really need to use 256MiB as the AUX buffer size?
IIRC, it means we allocate 256MiB per CPU for this case, on the other
hand, you could see the final perf data file size is small (0.681
MiB).
Seems to me, it's not necessary to allocate so big buffer for
the test, and I tried to run below 4 cases with 8MiB, all of them can
pass the testing :)
I didn't think anyone with a system with coresight support that would be
running perf record locally would only have 1GB of ram... I knew junos had
8GB and my dragonboard has 4GB ... so I know I was on the smaller side. I
thought a larger buffer == safer results (less chance of needing to write
out the buffer during capture). Admittdly I used 256Mb when my tests ran for
much longer and collected more data. I can try drop to 8 or 16gb and see.
Yes, my Juno board has 8GB but I also have DB410c with 1GB with quad
coes [1]. I am still concern for 256MB buffer size, it's not friendly for
embedded system, and even not good for server. For example, if we run
this testing on Arm server with 96 cores (like Hisilicon D06 board),
then we need the buffer size is:
256MiB * 96 = 16GiB
I agree usually 16GiB is not a problem for server, but seems to me
it doesn't make much sense to consume huge memory resource for the
testing.
In other words, if set 8MiB (or 16MiB, 32MiB) buffer size and doesn't
see testing result regression, I think this would be good to decrease
the buffer size.
[1] https://www.96boards.org/product/dragonboard410c/
[...]
diff --git a/tools/perf/tests/shell/coresight_asm_pure_loop.sh b/tools/perf/tests/shell/coresight_asm_pure_loop.sh
new file mode 100755
index 000000000000..3f0dbefcad50
--- /dev/null
+++ b/tools/perf/tests/shell/coresight_asm_pure_loop.sh
@@ -0,0 +1,18 @@
+#!/bin/sh -e
+# Coresight / ASM Pure Loop
+
+# SPDX-License-Identifier: GPL-2.0
+# Carsten Haitzler <carsten.haitzler@xxxxxxx>, 2021
+
+TEST="asm_pure_loop"
+. $(dirname $0)/lib/coresight.sh
+ARGS=""
+DATV="out"
+DATA="$DATD/perf-$TEST-$DATV.data"
+
+perf record $PERFRECOPT -o "$DATA" "$BIN" $ARGS
+
+perf_dump_aux_verify "$DATA" 10 10 10
+
+err=$?
+exit $err
Can we organize the shell scripts by moving them into the folder
tools/perf/tests/shell/coresight?
We can - but it comes with a fair few more changes.
coresight_asm_pure_loop.sh
coresight_memcpy_thread_16k_10.sh
coresight_thread_loop_check_tid_10.sh
coresight_thread_loop_check_tid_2.sh
coresight_unroll_loop_thread_10.sh
And we even can consider to move script test_arm_coresight.sh into
the folder tools/perf/tests/shell/coresight and change its
name as 'coresight_smoke_test.sh'.
Indeed these other tests I left alone for now and had not thought about how
to marry these together yet - leaving this for another day and another patch
set rather than this patch set itself. That was my thoguht. I was trying to
make an "Easier to extend by just dropping a test into a dir" setup here to
make maintenance and expansion easier over time (and thus encourage testing
by having a simple repeatable test infra to duplicate). I ended up with a
dir per test tool you need to build and a driver script in the tests/shell
dir. I think this is certainly worth considering but perhaps as a separate
set of work to marry these?
Okay, it would be fine to use separate set for moving the script
test_arm_coresight.sh, which is a simple case.
I piggybacked on the existing shell test infra but added a fair few more
scripts. To do what you suggest I'd need to modify the core shell test code
to walk subdirs recursively then looking for child scripts. The problem is
how does perf test's shell handling know about the coresight subdir vs the
lib subdir?
Yeah, now I understand your point. How about file layout like below?
tools/perf/tests/shell/coresight_test_hub.sh
tools/perf/tests/shell/coresight/coresight_asm_pure_loop.sh
tools/perf/tests/shell/coresight/coresight_memcpy_thread_16k_10.sh
tools/perf/tests/shell/coresight/coresight_thread_loop_check_tid_10.sh
tools/perf/tests/shell/coresight/coresight_thread_loop_check_tid_2.sh
tools/perf/tests/shell/coresight/coresight_unroll_loop_thread_10.sh
So we use tools/perf/tests/shell/coresight_test_hub.sh as an interface
to hook with Perf test infrastructure, and then hub.sh file calls
testing scripts under the sub folder. Seems to me, this is also
friendly for later's extension.
Both contain *.sh shell scripts - the difference is the ones in
lib are not executable. Is this sufficiently different? I could also open
them to check the have #!/bin/... as the first line. Hardcoding just a
single coresight subdir just feels wrong and hacky to me, thus the generic
recursion solution I suggest here.
Agreed. I also don't prefer this way.
I can definitely see how extending to subdirs would make supporting testing
cleaner and divide things into their own domains (dirs).
Thanks a lot for the work! The test cases are good for me (but I would
say Mike is the best person for reviewing testing trace data quaility),
I just want to make sure it's not hard for later maintenance.