June 2024 - Linux-kselftest-mirror

[PATCH v3 00/13] riscv: Add support for xtheadvector

by Charlie Jenkins

xtheadvector is a custom extension that is based upon riscv vector version 0.7.1 [1]. All of the vector routines have been modified to support this alternative vector version based upon whether xtheadvector was determined to be supported at boot. vlenb is not supported on the existing xtheadvector hardware, so a devicetree property thead,vlenb is added to provide the vlenb to Linux. There is a new hwprobe key RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 that is used to request which thead vendor extensions are supported on the current platform. This allows future vendors to allocate hwprobe keys for their vendor. Support for xtheadvector is also added to the vector kselftests. Signed-off-by: Charlie Jenkins <charlie(a)rivosinc.com> [1] https://github.com/T-head-Semi/thead-extension-spec/blob/95358cb2cca9489361… --- This series is a continuation of a different series that was fragmented into two other series in an attempt to get part of it merged in the 6.10 merge window. The split-off series did not get merged due to a NAK on the series that added the generic riscv,vlenb devicetree entry. This series has converted riscv,vlenb to thead,vlenb to remedy this issue. The original series is titled "riscv: Support vendor extensions and xtheadvector" [3]. The series titled "riscv: Extend cpufeature.c to detect vendor extensions" is still under development and this series is based on that series! [4] I have tested this with an Allwinner Nezha board. I ran into issues booting the board after 6.9-rc1 so I applied these patches to 6.8. There are a couple of minor merge conflicts that do arrise when doing that, so please let me know if you have been able to boot this board with a 6.9 kernel. I used SkiffOS [1] to manage building the image, but upgraded the U-Boot version to Samuel Holland's more up-to-date version [2] and changed out the device tree used by U-Boot with the device trees that are present in upstream linux and this series. Thank you Samuel for all of the work you did to make this task possible. [1] https://github.com/skiffos/SkiffOS/tree/master/configs/allwinner/nezha [2] https://github.com/smaeul/u-boot/commit/2e89b706f5c956a70c989cd31665f1429e9… [3] https://lore.kernel.org/all/20240503-dev-charlie-support_thead_vector_6_9-v… [4] https://lore.kernel.org/linux-riscv/20240609-support_vendor_extensions-v2-0… --- Changes in v3: - Add back Heiko's signed-off-by (Conor) - Mark RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 as a bitmask - Link to v2: https://lore.kernel.org/r/20240610-xtheadvector-v2-0-97a48613ad64@rivosinc.… Changes in v2: - Removed extraneous references to "riscv,vlenb" (Jess) - Moved declaration of "thead,vlenb" into cpus.yaml and added restriction that it's only applicable to thead cores (Conor) - Check CONFIG_RISCV_ISA_XTHEADVECTOR instead of CONFIG_RISCV_ISA_V for thead,vlenb (Jess) - Fix naming of hwprobe variables (Evan) - Link to v1: https://lore.kernel.org/r/20240609-xtheadvector-v1-0-3fe591d7f109@rivosinc.… --- Charlie Jenkins (12): dt-bindings: riscv: Add xtheadvector ISA extension description dt-bindings: cpus: add a thead vlen register length property riscv: dts: allwinner: Add xtheadvector to the D1/D1s devicetree riscv: Add thead and xtheadvector as a vendor extension riscv: vector: Use vlenb from DT for thead riscv: csr: Add CSR encodings for VCSR_VXRM/VCSR_VXSAT riscv: Add xtheadvector instruction definitions riscv: vector: Support xtheadvector save/restore riscv: hwprobe: Add thead vendor extension probing riscv: hwprobe: Document thead vendor extensions and xtheadvector extension selftests: riscv: Fix vector tests selftests: riscv: Support xtheadvector in vector tests Heiko Stuebner (1): RISC-V: define the elements of the VCSR vector CSR Documentation/arch/riscv/hwprobe.rst | 10 + Documentation/devicetree/bindings/riscv/cpus.yaml | 19 ++ .../devicetree/bindings/riscv/extensions.yaml | 10 + arch/riscv/Kconfig.vendor | 26 ++ arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi | 3 +- arch/riscv/include/asm/cpufeature.h | 2 + arch/riscv/include/asm/csr.h | 13 + arch/riscv/include/asm/hwprobe.h | 5 +- arch/riscv/include/asm/switch_to.h | 2 +- arch/riscv/include/asm/vector.h | 249 +++++++++++++---- arch/riscv/include/asm/vendor_extensions/thead.h | 42 +++ .../include/asm/vendor_extensions/thead_hwprobe.h | 18 ++ .../include/asm/vendor_extensions/vendor_hwprobe.h | 37 +++ arch/riscv/include/uapi/asm/hwprobe.h | 3 +- arch/riscv/include/uapi/asm/vendor/thead.h | 3 + arch/riscv/kernel/cpufeature.c | 51 +++- arch/riscv/kernel/kernel_mode_vector.c | 8 +- arch/riscv/kernel/process.c | 4 +- arch/riscv/kernel/signal.c | 6 +- arch/riscv/kernel/sys_hwprobe.c | 5 + arch/riscv/kernel/vector.c | 25 +- arch/riscv/kernel/vendor_extensions.c | 10 + arch/riscv/kernel/vendor_extensions/Makefile | 2 + arch/riscv/kernel/vendor_extensions/thead.c | 18 ++ .../riscv/kernel/vendor_extensions/thead_hwprobe.c | 19 ++ tools/testing/selftests/riscv/vector/.gitignore | 3 +- tools/testing/selftests/riscv/vector/Makefile | 17 +- .../selftests/riscv/vector/v_exec_initval_nolibc.c | 93 +++++++ tools/testing/selftests/riscv/vector/v_helpers.c | 67 +++++ tools/testing/selftests/riscv/vector/v_helpers.h | 7 + tools/testing/selftests/riscv/vector/v_initval.c | 22 ++ .../selftests/riscv/vector/v_initval_nolibc.c | 68 ----- .../selftests/riscv/vector/vstate_exec_nolibc.c | 20 +- .../testing/selftests/riscv/vector/vstate_prctl.c | 295 ++++++++++++--------- 34 files changed, 911 insertions(+), 271 deletions(-) --- base-commit: 11cc01d4d2af304b7288251aad7e03315db8dffc change-id: 20240530-xtheadvector-833d3d17b423 -- - Charlie

5 months, 2 weeks

6
26
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[RFC] ktap_v2: KTAP specification transition method

by Frank Rowand

In the middle of the thread about a patch to add the skip test result, I suggested documenting the process of deprecating the KTAP v1 Specification method of marking a skipped test: https://lore.kernel.org/all/490271eb-1429-2217-6e38-837c6e5e328b@gmail.com/… In a reply to that email I suggested that we ought to have a process to transition the KTAP Specification from v1 to v2, and possibly v3 and future. This email is meant to be the root of that discussion. My initial thinking is that there are at least three different types of project and/or community that may have different needs in this area. Type 1 - project controls both the test output generation and the test output parsing tool. Both generation and parsing code are in the same repository and/or synchronized versions are distributed together. Devicetree unittests are an example of Type 1. I plan to maintain changes of test output to KTAP v2 format in coordination with updating the parser to process KTAP v2 data. Type 2 - project controls both the test output generation and the test output parsing tool. The test output generation and a parser modifications may be controlled by the project BUT there are one or more external testing projects that (1) may have their own parsers, and (2) may have a single framework that tests multiple versions of the tests. I think that kselftest and kunit tests are probably examples of Type 2. I also think that DT unittests will become a Type 2 project as a result of converting to KTAP v2 data. Type 3 - project may create and maintain some tests, but is primarily a consumer of tests created by other projects. Type 3 projects typically have a single framework that is able to execute and process multiple versions of the tests. The Fuego test project is an example of Type 3. Maybe adding all of this complexity of different Types in my initial thinking was silly -- maybe everything in this topic is governed by the more complex Type 3. My thinking was that the three different Types of project would be impacted in different ways by transition plans. Type 3 would be the most impacted, so I wanted to be sure that any transition plan especially considered their needs. There is an important aspect of the KTAP format that might ease the transition from one version to another: All KTAP formatted results begin with a "version line", so as soon as a parser has processed the first line of a test, it can apply the appropriate KTAP Specification version to all subsequent lines of test output. A parser implementation could choose to process all versions, could choose to invoke a version specific parser, or some other approach all together. In the "add skip test results" thread, I suggested deprecating the v1 method of marking a skipped test in v2, with a scheduled removal of the v1 method in v3. But since the KTAP format version is available in the very first line of test output, is it necessary to do a slow deprecation and removal over two versions? One argument to doing a two version deprecation/removal process is that a parser that is one version older the the test output _might_ be able to process the test output without error, but would not be able to take advantage of features added in the newer version of the Specification. My opinion is that a two version deprecation/removal process will slow the Specification update process and lead to more versions of the Specification over a given time interval. A one version deprecation/removal process puts more of a burden on Type 3 projects and external parsers for Type 2 projects to implement parsers that can process the newer Specification more quickly and puts a burden on test maintainers to delay a move to the newer Specification, or possibly pressure to support selection of more than one Specification version format for output data. One additional item... On the KTAP Specification version 2 process wiki page, I suggested that it is "desirable for test result parsers that understand the KTAP Specification version 2 data also be able to parse version 1 data." With the implication "Converting version 1 compliant data to version 2 compliant data should not require a "flag day" switch of test result parsers." If this thread discussion results in a different decision, I will update the wiki. Thoughts? -Frank

5 months, 2 weeks

3
2
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[PATCH v2 0/4] kselftests: vdso: conform tests to TAP output

by Muhammad Usama Anjum

Conform individual tests to TAP output. One patch conform one test. With this series, all vDSO tests become TAP conformant. First patch conform the test by using kselftest_harness.h. Other patches are conforming using default kselftest.h helpers. All tests have been tested multiple times before and after these patches. They are working correctly and outputting TAP messaging to find failures quikly when they happen. --- Changes since v1: - Update cover letter - Update commit message of first patch Muhammad Usama Anjum (4): kselftests: vdso: vdso_test_clock_getres: conform test to TAP output kselftests: vdso: vdso_test_correctness: conform test to TAP output kselftests: vdso: vdso_test_getcpu: conform test to TAP output kselftests: vdso: vdso_test_gettimeofday: conform test to TAP output .../selftests/vDSO/vdso_test_clock_getres.c | 68 ++++---- .../selftests/vDSO/vdso_test_correctness.c | 146 +++++++++--------- .../testing/selftests/vDSO/vdso_test_getcpu.c | 16 +- .../selftests/vDSO/vdso_test_gettimeofday.c | 23 +-- 4 files changed, 126 insertions(+), 127 deletions(-) -- 2.39.2

5 months, 2 weeks

2
10
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[PATCH 0/6] defconfig: drop RT_GROUP_SCHED=y

by Celeste Liu

For cgroup v1, if turned on, and there's any cgroup in the "cpu" hierarchy it needs an RT budget assigned, otherwise the processes in it will not be able to get RT at all. The problem with RT group scheduling is that it requires the budget assigned but there's no way we could assign a default budget, since the values to assign are both upper and lower time limits, are absolute, and need to be sum up to < 1 for each individal cgroup. That means we cannot really come up with values that would work by default in the general case.[1] For cgroup v2, it's almost unusable as well. If it turned on, the cpu controller can only be enabled when all RT processes are in the root cgroup. But it will lose the benefits of cgroup v2 if all RT process were placed in the same cgroup. Red Hat, Gentoo, Arch Linux and Debian all disable it. systemd also doesn't support it.[2] I leave tools/testing/selftests/bpf/config.{s390x,aarch64} untouched because I don't whether bpf testing requires it. [1]: https://bugzilla.redhat.com/show_bug.cgi?id=1229700 [2]: https://github.com/systemd/systemd/issues/13781#issuecomment-549164383 Celeste Liu (6): riscv: defconfig: drop RT_GROUP_SCHED=y loongarch: defconfig: drop RT_GROUP_SCHED=y mips: defconfig: drop RT_GROUP_SCHED=y from generic/db1xxx/eyeq5 powerpc: defconfig: drop RT_GROUP_SCHED=y from ppc6xx_defconfig sh: defconfig: drop RT_GROUP_SCHED=y from sdk7786/urquell arm: defconfig: drop RT_GROUP_SCHED=y from bcm2855/tegra/omap2plus arch/arm/configs/bcm2835_defconfig | 1 - arch/arm/configs/omap2plus_defconfig | 1 - arch/arm/configs/tegra_defconfig | 1 - arch/loongarch/configs/loongson3_defconfig | 1 - arch/mips/configs/db1xxx_defconfig | 1 - arch/mips/configs/eyeq5_defconfig | 1 - arch/mips/configs/generic_defconfig | 1 - arch/powerpc/configs/ppc6xx_defconfig | 1 - arch/riscv/configs/defconfig | 1 - arch/sh/configs/sdk7786_defconfig | 1 - arch/sh/configs/urquell_defconfig | 1 - 11 files changed, 11 deletions(-) -- 2.45.1

5 months, 2 weeks

6
12
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[PATCH v2] selftest: acct: Add selftest for the acct() syscall

by Abdulrasaq Lawani

Noticed that there was no selftest for the acct() syscall which enables the kernel to record terminated processes into a specified file. The acct() system call enables or disables process accounting. If accounting is turned on, records for each terminating process are appended to a specified filename as it terminates. An argument of NULL causes accounting to be turned off. This patch provides a test for the acct() syscall. References: https://man7.org/linux/man-pages/man2/acct.2.html Signed-off-by: Abdulrasaq Lawani <abdulrasaqolawani(a)gmail.com> --- Changes in v2: Add testcases to test error conditions. Add kselftest function for reporting results. - Link to v1: https://lore.kernel.org/r/20240622-kselftest-acct-syscall-v1-1-d270b5be8d37… --- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/acct/.gitignore | 2 + tools/testing/selftests/acct/Makefile | 4 ++ tools/testing/selftests/acct/acct_syscall.c | 89 +++++++++++++++++++++++++++++ 4 files changed, 96 insertions(+) diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 9039f3709aff..45a58ef5ad92 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -1,4 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 +TARGETS += acct TARGETS += alsa TARGETS += amd-pstate TARGETS += arm64 diff --git a/tools/testing/selftests/acct/.gitignore b/tools/testing/selftests/acct/.gitignore new file mode 100644 index 000000000000..8ab358d81bd2 --- /dev/null +++ b/tools/testing/selftests/acct/.gitignore @@ -0,0 +1,2 @@ +acct_syscall +config \ No newline at end of file diff --git a/tools/testing/selftests/acct/Makefile b/tools/testing/selftests/acct/Makefile new file mode 100644 index 000000000000..ff3e238c5634 --- /dev/null +++ b/tools/testing/selftests/acct/Makefile @@ -0,0 +1,4 @@ +TEST_GEN_PROGS := acct_syscall +CFLAGS += -Wall + +include ../lib.mk \ No newline at end of file diff --git a/tools/testing/selftests/acct/acct_syscall.c b/tools/testing/selftests/acct/acct_syscall.c new file mode 100644 index 000000000000..4fa00a88a1bd --- /dev/null +++ b/tools/testing/selftests/acct/acct_syscall.c @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* kselftest for acct() system call + * The acct() system call enables or disables process accounting. + */ + +#include <stdio.h> +#include <errno.h> +#include <string.h> +#include <sys/wait.h> + +#include "../kselftest.h" + +int main(void) +{ + // Setting up kselftest framework + ksft_print_header(); + ksft_set_plan(1); + + // Create file to log closed processes + char filename[] = "process_log"; + FILE *fp; + + fp = fopen(filename, "w"); + + int i = acct(filename); + + // Handle error conditions + if (i) { + switch (errno) { + case EPERM: + ksft_test_result_error("%s. Please run the test as root.\n", + strerror(errno)); + break; + + case EACCES: + ksft_test_result_error("Insufficient privilege.\n"); + break; + + case EIO: + ksft_test_result_error("Error writing to the file: %s.\n", filename); + break; + + default: + ksft_test_result_error("%s.\n", strerror(errno)); + break; + } + + remove(filename); + fclose(fp); + ksft_finished(); + return 1; + } + + // Create child process and wait for it to terminate. + pid_t child_pid; + + child_pid = fork(); + + if (child_pid < 0) { + ksft_test_result_error("Process failed\n"); + ksft_finished(); + return 1; + } else if (child_pid == 0) { + ksft_print_msg("Child process successfully created!\n"); + } else { + wait(NULL); + fseek(fp, 0L, SEEK_END); + int sz = ftell(fp); + + ksft_print_msg("Parent process successfully created!\n"); + + i = acct(NULL); + + if (sz <= 0) { + ksft_test_result_fail("Terminated child process not logged"); + ksft_exit_fail(); + return 1; + } + + ksft_test_result_pass("Successfully logged terminated process.\n"); + remove(filename); + fclose(fp); + ksft_exit_pass(); + return 0; + } + + return 1; +} --- base-commit: 50736169ecc8387247fe6a00932852ce7b057083 change-id: 20240622-kselftest-acct-syscall-2d90f7666b1e Best regards, -- Abdulrasaq Lawani <abdulrasaqolawani(a)gmail.com>

5 months, 2 weeks

2
1
0 0

[PATCH 0/1] KVM: selftests: pmu_counters_test: increase robustness of LLC cache misses

by Maxim Levitsky

Recent CI failures brought my attention to the fact that pmu_counters_test sometimes fails because it doesn't get any LLC cache misses. It apparently happens because CLFLUSH can race with CPU prediction. To attempt to fix this, implement a more aggressive cache flushing - now it is flushed on each iteration of the measured loop which should at least reduce by order of magnitude the chance of this happening. This patch survived more that a day of running in a loop on a Comet Lake machine, where the test used to fail after about 10-20 minites. Best regards, Maxim Levitsky Maxim Levitsky (1): KVM: selftests: pmu_counters_test: increase robustness of LLC cache misses .../selftests/kvm/x86_64/pmu_counters_test.c | 20 +++++++++---------- 1 file changed, 9 insertions(+), 11 deletions(-) -- 2.26.3

5 months, 2 weeks

2
4
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[PATCH v3 0/7] selftests/x86: fix build errors and warnings found via clang

by John Hubbard

Hi, Dave Hansen, Muhammad Usama Anjum, here is the combined series that we discussed yesterday [1]. As I mentioned then, this is a bit intrusive--but no more than necessary, IMHO. Specifically, it moves some clang-un-inlineable things out to "pure" assembly code files. I've tested this by building with clang, then running each binary on my x86_64 test system with today's 6.10-rc1, and comparing the console and dmesg output to a gcc-based build without these patches applied. Aside from timestamps and virtual addresses, it looks identical. Earlier cover letter: Just a bunch of build and warnings fixes that show up when building with clang. Some of these depend on each other, so I'm sending them as a series. Changes since v2: 1) Dropped my test_FISTTP.c patch, and picked up Muhammad's fix instead, seeing as how that was posted first. 2) Updated patch descriptions to reflect that Valentin Obst's build fix for LLVM [1] has already been merged into Linux main. 3) Minor wording and typo corrections in the commit logs throughout. Changes since the first version: 1) Rebased onto Linux 6.10-rc1 Enjoy! [1] https://lore.kernel.org/44428518-4d21-4de7-8587-04eceefb330d@nvidia.com thanks, John Hubbard John Hubbard (6): selftests/x86: fix Makefile dependencies to work with clang selftests/x86: build fsgsbase_restore.c with clang selftests/x86: build sysret_rip.c with clang selftests/x86: avoid -no-pie warnings from clang during compilation selftests/x86: remove (or use) unused variables and functions selftests/x86: fix printk warnings reported by clang Muhammad Usama Anjum (1): selftests: x86: test_FISTTP: use fisttps instead of ambiguous fisttp tools/testing/selftests/x86/Makefile | 31 +++++++++++++++---- tools/testing/selftests/x86/amx.c | 16 ---------- .../testing/selftests/x86/clang_helpers_32.S | 11 +++++++ .../testing/selftests/x86/clang_helpers_64.S | 28 +++++++++++++++++ tools/testing/selftests/x86/fsgsbase.c | 6 ---- .../testing/selftests/x86/fsgsbase_restore.c | 11 +++---- tools/testing/selftests/x86/sigreturn.c | 2 +- .../testing/selftests/x86/syscall_arg_fault.c | 1 - tools/testing/selftests/x86/sysret_rip.c | 20 ++++-------- tools/testing/selftests/x86/test_FISTTP.c | 8 ++--- tools/testing/selftests/x86/test_vsyscall.c | 15 +++------ tools/testing/selftests/x86/vdso_restorer.c | 2 ++ 12 files changed, 87 insertions(+), 64 deletions(-) create mode 100644 tools/testing/selftests/x86/clang_helpers_32.S create mode 100644 tools/testing/selftests/x86/clang_helpers_64.S base-commit: 4a4be1ad3a6efea16c56615f31117590fd881358 -- 2.45.1

5 months, 2 weeks

2
12
0 0

[PATCH 0/2] Modify the watchdog selftest for execution with kselftest runner

by Laura Nao

The watchdog selftest script supports various parameters for testing different IOCTLs. The watchdog ping functionality is validated by starting a loop where the watchdog device is periodically pet, which can only be stopped by the user interrupting the script. This results in a timeout when running this test using the kselftest runner with no non-oneshot parameters (or no parameters at all): TAP version 13 1..1 # timeout set to 45 # selftests: watchdog: watchdog-test # Watchdog Ticking Away! # .............................................# not ok 1 selftests: watchdog: watchdog-test # TIMEOUT 45 seconds To address this issue, the first patch in this series limits the loop to 5 iterations by default and adds support for a new '-c' option to customize the number of pings as required. The second patch conforms the test output to the KTAP format. Laura Nao (2): selftests/watchdog: limit ping loop and allow configuring the number of pings selftests/watchdog: convert the test output to KTAP format .../selftests/watchdog/watchdog-test.c | 166 +++++++++++------- 1 file changed, 101 insertions(+), 65 deletions(-) -- 2.30.2

5 months, 3 weeks

2
14
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[PATCH bpf-next v6 0/9] use network helpers, part 8

by Geliang Tang

From: Geliang Tang <tanggeliang(a)kylinos.cn> v6: - update patch 6 as Daniel suggested. (thanks) v5: - keep make_server and make_client as Eduard suggested. v4: - a new patch to use make_sockaddr in sockmap_ktls. - a new patch to close fd in error path in drop_on_reuseport. - drop make_server() in patch 7. - drop make_client() too in patch 9. v3: - a new patch to add backlog for network_helper_opts. - use start_server_str in sockmap_ktls now, not start_server. v2: - address Eduard's comments in v1. (thanks) - fix errors reported by CI. This patch set uses network helpers in sockmap_ktls and sk_lookup, and drop three local helpers tcp_server(), inetaddr_len() and make_socket() in them. Geliang Tang (9): selftests/bpf: Add backlog for network_helper_opts selftests/bpf: Use start_server_str in sockmap_ktls selftests/bpf: Use connect_to_fd in sockmap_ktls selftests/bpf: Use make_sockaddr in sockmap_ktls selftests/bpf: Close fd in error path in drop_on_reuseport selftests/bpf: Use start_server_str in sk_lookup selftests/bpf: Use connect_to_fd in sk_lookup selftests/bpf: Use connect_to_addr in sk_lookup selftests/bpf: Drop make_socket in sk_lookup tools/testing/selftests/bpf/network_helpers.c | 2 +- tools/testing/selftests/bpf/network_helpers.h | 1 + .../selftests/bpf/prog_tests/sk_lookup.c | 141 +++++++----------- .../selftests/bpf/prog_tests/sockmap_ktls.c | 51 ++----- 4 files changed, 61 insertions(+), 134 deletions(-) -- 2.43.0

5 months, 3 weeks

2
14
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[RFC PATCH 0/3] tracing: Support poll on event hist file

by Masami Hiramatsu (Google)

Hi, Here is an RFC patch to support polling on event 'hist' file. There has been interest in allowing user programs to monitor kernel events in real time. Ftrace provides `trace_pipe` interface to wait on events in the ring buffer, but it is needed to wait until filling up a page with events in the ring buffer. We can also peek the `trace` file periodically, but that is inefficient way to monitor a randomely happening event. This patch set allows user to `poll`(or `select`, `epoll`) on event histogram interface. As you know each event has its own `hist` file which shows histograms generated by trigger action. So user can set a new hist trigger on any event you want to monitor, and poll on the `hist` file until it is updated. There are 2 poll events are supported, POLLIN and POLLPRI. POLLIN means that there are any readable update on `hist` file and this event will be flashed only when you call read(). So, this is useful if you want to read the histogram periodically. The other POLLPRI event is for monitoring trace event. Like the POLLIN, this will be returned when the histogram is updated, but you don't need to read() the file and use poll() again. Note that this waits for histogram update (not event arrival), thus you must set a histogram on the event at first. Here is an example usage: ---- TRACEFS=/sys/kernel/tracing EVENT=$TRACEFS/events/sched/sched_process_free # setup histogram trigger and enable event echo "hist:key=comm" >> $EVENT/trigger echo 1 > $EVENT/enable # Wait for update poll $EVENT/hist # Event arrived. echo "process free event is comming" tail $TRACEFS/trace ---- The 'poll' command is in the selftest patch. You can take this series also from here; https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/log/?h=t… Thank you, --- Masami Hiramatsu (Google) (3): tracing/hist: Add poll(POLLIN) support on hist file tracing/hist: Support POLLPRI event for poll on histogram selftests/tracing: Add hist poll() support test include/linux/trace_events.h | 5 + kernel/trace/trace_events.c | 18 ++++ kernel/trace/trace_events_hist.c | 101 +++++++++++++++++++- tools/testing/selftests/ftrace/Makefile | 3 + tools/testing/selftests/ftrace/poll.c | 34 +++++++ .../ftrace/test.d/trigger/trigger-hist-poll.tc | 46 +++++++++ 6 files changed, 204 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/ftrace/poll.c create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc -- Masami Hiramatsu (Google) <mhiramat(a)kernel.org>

5 months, 3 weeks

3
5
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Linux-kselftest-mirror June 2024