kernel/linux.git/tools/perf/util/session.c, branch v7.0-rc7

perf thread: Don't require machine to compute the e_machine

2026-02-03T21:01:27+00:00

The machine can be calculated from a thread via its maps. Don't require the machine argument to simplify callers and also to delay computing the machine until a little later. Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Albert Ou Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Andi Kleen Cc: Andrew Jones Cc: Anubhav Shelat Cc: Anup Patel Cc: Athira Rajeev Cc: Blake Jones Cc: Chun-Tse Shao Cc: Dapeng Mi Cc: Dmitriy Vyukov Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Leo Yan Cc: Namhyung Kim Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Quan Zhou Cc: Shimin Guo Cc: Swapnil Sapkal Cc: Thomas Falcon Cc: Will Deacon Cc: Yunseong Kim Signed-off-by: Arnaldo Carvalho de Melo

perf header: Add e_machine/e_flags to the header

2026-02-03T21:01:27+00:00

Add 64-bits of feature data to record the ELF machine and flags. This allows readers to initialize based on the data. For example, `perf kvm stat` wants to initialize based on the kind of data to be read, but at initialization time there are no threads to base this data upon and using the host means cross platform support won't work. The values in the perf_env also act as a cache for these within the session. Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Albert Ou Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Andi Kleen Cc: Andrew Jones Cc: Anubhav Shelat Cc: Anup Patel Cc: Athira Rajeev Cc: Blake Jones Cc: Chun-Tse Shao Cc: Dapeng Mi Cc: Dmitriy Vyukov Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Leo Yan Cc: Namhyung Kim Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Quan Zhou Cc: Shimin Guo Cc: Swapnil Sapkal Cc: Thomas Falcon Cc: Will Deacon Cc: Yunseong Kim Signed-off-by: Arnaldo Carvalho de Melo

perf session: Add e_flags to the e_machine helper

2026-02-03T21:01:27+00:00

Allow e_flags as well as e_machine to be computed using the e_machine helper. This isn't currently used, the argument is always NULL, but it will be used for a new header feature. Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Albert Ou Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Andi Kleen Cc: Andrew Jones Cc: Anubhav Shelat Cc: Anup Patel Cc: Athira Rajeev Cc: Blake Jones Cc: Chun-Tse Shao Cc: Dapeng Mi Cc: Dmitriy Vyukov Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Leo Yan Cc: Namhyung Kim Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Quan Zhou Cc: Shimin Guo Cc: Swapnil Sapkal Cc: Thomas Falcon Cc: Will Deacon Cc: Yunseong Kim Signed-off-by: Arnaldo Carvalho de Melo

perf session: Don't write to memory pointed to a const pointer

2026-01-27T05:09:37+00:00

Since it is freshly allocated just attribute it to a non-const pointer and then change it via that pointer. That way we avoid const-correctness warnings in recent glibc versions. Signed-off-by: Arnaldo Carvalho de Melo

perf session: Print all machines in session dump

2026-01-26T21:32:10+00:00

perf_session__fprintf() prints only the host. This has been changed to print details of host and all guests, by traversing through the RB-Tree. These are visible when using high verbosity (-vvvv) in KVM environments, during perf report dumps. Testing: - Test 1: Record the local machine and guest VM using 'perf kvm record' and generate the report using 'perf kvm report -vvvv -D'. The dump should show the threads and other details related to local and guest machine. - 1 Ubuntu VM running on Fedora host - VM is running a noisy program => $ dd if=/dev/urandom of=/dev/null - On host run => $ sudo ./perf kvm --guestvmlinux=/tmp/shared/guest_vmlinux \ --guestkallsyms=/tmp/shared/guest_kallsyms \ --guestmodules=/tmp/shared/guest_modules \ record -a -g -o perf.data.guest and exit after a few seconds. [ perf record: Woken up 9 times to write data ] [ perf record: Captured and wrote 3.150 MB perf.data.guest \ (29311 samples) ] - Generate dump => $ sudo ./perf kvm --guestkallsyms /tmp/shared/guest_kallsyms \ report -vvvv -D -i perf.data.guest > output.txt - Check for threads associated with guest machine. $ grep "Thread 0" output.txt Thread 0 swapper Thread 0 [guest/0] PASS - Test 2: Record the local machine and guest VM using 'perf kvm record' and generate the report using 'perf kvm report'. The functions running on guest VM should be seen in the report. - Same setup as Test 1 but the test looks at the performance profile, to check if the function names are visible. - Peek into profile using => $ sudo ./perf kvm --guestkallsyms /tmp/shared/guest_kallsyms \ report -i perf.data.guest - Samples: 29K of event 'cycles', Event count (approx.): 28711693142 Children Self Command Shared Object Symbol 35.69% 35.69% :5820 [guest.kernel.kallsyms] [g] chacha_permute 11.56% 11.56% :5820 [guest.kernel.kallsyms] [g] entry_SYSRETQ_unsXXX 11.12% 11.12% :5820 [guest.kernel.kallsyms] [g] syscall_return_viXXX 7.36% 7.36% :5820 [guest.kernel.kallsyms] [g] entry_SYSCALL_64_XXX 6.07% 6.07% :5820 [guest.kernel.kallsyms] [g] chacha_block_generic 5.40% 5.40% :5820 [guest.kernel.kallsyms] [g] _copy_to_iter .... PASS - Test 3: Record the local and 2 guest VMs using 'perf kvm record' and generate the report using 'perf kvm report -vvvv -D'. The dump should show the threads and other details related to local and guest machines. - 1 Ubuntu and 1 Alpine VMs running on Fedora host. - Find PIDs of qemu instances and use them during record and report $ pgrep qemu 5816 25098 - Record the activity => $ sudo ./perf kvm record -p 5816,25098 -a -g -o perf.data.guests Warning: PID/TID switch overriding SYSTEM [ perf record: Woken up 325927 times to write data ] [ perf record: Captured and wrote 3.692 MB perf.data.guests \ (57389 samples) ] - Generate dump => $ sudo ./perf kvm report -vvvv -D -i perf.data.guests > output.txt - Check if the threads related to the local machine and guest VMs are present => $ grep "Thread 0" output.txt Thread 0 swapper Thread 0 [guest/0] NOTE: Threads from Ubuntu and Alpine VMs are bundled together and appear as one guest machine. Looking into output.txt => Threads: 6 Thread 0 [guest/0] Thread 5816 :5816 Thread 25098 :25098 Thread 5819 :5819 Thread 5820 :5820 Thread 25103 :25103 To conclude, information is collected for both VMs and not listed as two different guest machines. PASS - Test 4: Check if any guest-related information is printed in perf annotate. This test is included because the command calls perf_session__fprintf() in its code path when using -vvvv option. This could be explained by inability / lack of options for 'perf annotate' to look into guest VM from host machine, due to no option to specify the guest's kallsyms or modules. A similar explanation for 'perf mem' could be used, as perf_session__fprintf() is also present in its code path. - Run annotate => $ sudo ./perf annotate -i perf.data.guest -vvvv > output.txt - Check for threads from local machine or guest VM => $ grep "Thread 0" output.txt Thread 0 swapper Threads from local machine are found while threads from guest VM are not found. It is possibly because of a lack of a guest kallsyms option for DSO matching in perf annotate. PASS - Test 5: Run kvm test available on perf path - $ sudo ./perf test kvm 89: perf kvm tests : Ok PASS Signed-off-by: Hrishikesh Suresh Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Blake Jones Cc: Chun-Tse Shao Cc: Dmitriy Vyukov Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Leo Yan Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra [ Declare 'nd' in the 'for' line and and 'pos' inside the loop body, to make it more compact ] Signed-off-by: Arnaldo Carvalho de Melo

perf perf_regs: Accurately compute register names for CSKY

2026-01-26T21:31:16+00:00

CSKY needs the e_flags to determine the ABI level and know whether additional registers are encoded or not. Wire this up now that the e_flags for a thread can be determined. Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Athira Rajeev Cc: Chun-Tse Shao Cc: Guo Ren Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Sergei Trofimovich Cc: Shimin Guo Cc: Stephen Brennan Cc: Swapnil Sapkal Cc: Tianyou Li [ Conditionally define EF_CSKY_ABIMASK and EF_CSKY_ABIV2 for older distros ] Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Add optional e_flags output argument to thread__e_machine

2026-01-26T21:21:20+00:00

The e_flags are needed to accurately compute complete perf register information for CSKY. Add the ability to read and have this value associated with a thread. This change doesn't wire up the use of the e_flags except in disasm where use already exists but just wasn't set up yet. Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Athira Rajeev Cc: Chun-Tse Shao Cc: Guo Ren Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Sergei Trofimovich Cc: Shimin Guo Cc: Stephen Brennan Cc: Swapnil Sapkal Cc: Tianyou Li Signed-off-by: Arnaldo Carvalho de Melo

perf sched stats: Add record and rawdump support

2026-01-22T15:29:28+00:00

Define new, perf tool only, sample types and their layouts. Add logic to parse /proc/schedstat, convert it to perf sample format and save samples to perf.data file with `perf sched stats record` command. Also add logic to read perf.data file, interpret schedstat samples and print rawdump of samples with `perf script -D`. Note that, /proc/schedstat file output is standardized with version number. The patch supports v15 but older or newer version can be added easily. Co-developed-by: Ravi Bangoria Signed-off-by: Ravi Bangoria Signed-off-by: Swapnil Sapkal Tested-by: Chen Yu Tested-by: James Clark Acked-by: Ian Rogers Acked-by: Peter Zijlstra Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Anubhav Shelat Cc: Ben Gainey Cc: Blake Jones Cc: Chun-Tse Shao Cc: David Vernet Cc: Dmitriy Vyukov Cc: Dr. David Alan Gilbert Cc: Gautham Shenoy Cc: Graham Woodward Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Juri Lelli Cc: K Prateek Nayak Cc: Kan Liang Cc: Leo Yan Cc: Madadi Vineeth Reddy Cc: Mark Rutland Cc: Namhyung Kim Cc: Sandipan Das Cc: Santosh Shukla Cc: Shrikanth Hegde Cc: Steven Rostedt (VMware) Cc: Tejun Heo Cc: Thomas Falcon Cc: Tim Chen Cc: Vincent Guittot Cc: Yang Jihong Cc: Yujie Liu Cc: Zhongqiu Han [ PRIu64 needs uint64_t, not 'unsigned long' to work on both 32-bit and 64-bit ] Signed-off-by: Arnaldo Carvalho de Melo

perf perf_regs: Switch from arch string to int e_machine

2026-01-20T18:43:04+00:00

The arch string requires multiple strcmp to identify things like the IP and SP. Switch to passing in an e_machine that in the bulk of cases is computed using a current thread load. The e_machine also allows identification of 32-bit vs 64-bit processes. Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Albert Ou Cc: Alexandre Ghiti Cc: Andi Kleen Cc: Athira Rajeev Cc: Chun-Tse Shao Cc: Dmitriy Vyukov Cc: Dr. David Alan Gilbert Cc: Guo Ren Cc: Haibo Xu Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Krzysztof Łopatowski Cc: Leo Yan Cc: Mark Wielaard Cc: Namhyung Kim Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Sergei Trofimovich Cc: Shimin Guo Cc: Stephen Brennan Cc: Thomas Falcon Cc: Will Deacon [ Include dwarf-regs.h to get conditional defines for EM_CSKY and EM_LOONGARCH, not available in old distros ] Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Switch printf("...%s", strerror(errno)) to printf("...%m")

2026-01-14T20:22:50+00:00

strerror() has thread safety issues, strerror_r() requires stack allocated buffers. Code in perf has already been using the "%m" formatting flag that is a widely support glibc extension to print the current errno's description. Expand the usage of this formatting flag and remove usage of strerror()/strerror_r(). Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Blake Jones Cc: Chun-Tse Shao Cc: Dmitriy Vyukov Cc: Dr. David Alan Gilbert Cc: Haibo Xu Cc: Howard Chu Cc: Ingo Molnar Cc: Jiri Olsa Cc: Leo Yan Cc: Peter Zijlstra Cc: Stephen Brennan Cc: Thomas Falcon Cc: Yunseong Kim Cc: Zhongqiu Han Signed-off-by: Arnaldo Carvalho de Melo