kernel/linux.git/tools/tracing/rtla/src/timerlat_hist.c, branch linux-6.9.y

rtla/timerlat: Fix histogram report when a cpu count is 0

2024-06-16T11:51:07+00:00

commit 01b05fc0e5f3aec443a9a8ffa0022cbca2fd3608 upstream. On short runs it is possible to get no samples on a cpu, like this: # rtla timerlat hist -u -T50 Index IRQ-001 Thr-001 Usr-001 IRQ-002 Thr-002 Usr-002 2 1 0 0 0 0 0 33 0 1 0 0 0 0 36 0 0 1 0 0 0 49 0 0 0 1 0 0 52 0 0 0 0 1 0 over: 0 0 0 0 0 0 count: 1 1 1 1 1 0 min: 2 33 36 49 52 18446744073709551615 avg: 2 33 36 49 52 - max: 2 33 36 49 52 0 rtla timerlat hit stop tracing IRQ handler delay: (exit from idle) 48.21 us (91.09 %) IRQ latency: 49.11 us Timerlat IRQ duration: 2.17 us (4.09 %) Blocking thread: 1.01 us (1.90 %) swapper/2:0 1.01 us ------------------------------------------------------------------------ Thread latency: 52.93 us (100%) Max timerlat IRQ latency from idle: 49.11 us in cpu 2 Note, the value 18446744073709551615 is the same as ~0. Fix this by reporting no results for the min, avg and max if the count is 0. Link: https://lkml.kernel.org/r/20240510190318.44295-1-jkacur@redhat.com Cc: stable@vger.kernel.org Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode") Suggested-by: Daniel Bristot de Oliveria Signed-off-by: John Kacur Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Greg Kroah-Hartman

tools/rtla: Add -U/--user-load option to timerlat

2024-03-20T04:39:06+00:00

The timerlat tracer provides an interface for any application to wait for the timerlat's periodic wakeup. Currently, rtla timerlat uses it to dispatch its user-space workload (-u option). But as the tracer interface is generic, rtla timerlat can also be used to monitor any workload that uses it. For example, a user might place their own workload to wait on the tracer interface, and monitor the results with rtla timerlat. Add the -U option to rtla timerlat top and hist. With this option, rtla timerlat will not dispatch its workload but only setting up the system, waiting for a user to dispatch its workload. The sample code in this patch is an example of python application that loops in the timerlat tracer fd. To use it, dispatch: # rtla timerlat -U In a terminal, then run the python program on another terminal, specifying the CPU to run it. For example, setting on CPU 1: #./timerlat_load.py 1 Then rtla timerlat will start printing the statistics of the ./timerlat_load.py app. An interesting point is that the "Ret user Timer Latency" value is the overall response time of the load. The sample load does a memory copy to exemplify that. The stop tracing options on rtla timerlat works in this setup as well, including auto analysis. Link: https://lkml.kernel.org/r/36e6bcf18fe15c7601048fd4c65aeb193c502cc8.1707229706.git.bristot@kernel.org Cc: Jonathan Corbet Cc: Masami Hiramatsu Signed-off-by: Daniel Bristot de Oliveira

tools/rtla: Exit with EXIT_SUCCESS when help is invoked

2024-02-12T09:59:09+00:00

Fix rtla so that the following commands exit with 0 when help is invoked rtla osnoise top -h rtla osnoise hist -h rtla timerlat top -h rtla timerlat hist -h Link: https://lore.kernel.org/linux-trace-devel/20240203001607.69703-1-jkacur@redhat.com Cc: stable@vger.kernel.org Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode") Signed-off-by: John Kacur Signed-off-by: Daniel Bristot de Oliveira

tools/rtla: Fix uninitialized bucket/data->bucket_size warning

2024-02-12T08:56:22+00:00

When compiling rtla with clang, I am getting the following warnings: $ make HOSTCC=clang CC=clang LLVM_IAS=1 [..] clang -O -g -DVERSION=\"6.8.0-rc3\" -flto=auto -fexceptions -fstack-protector-strong -fasynchronous-unwind-tables -fstack-clash-protection -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS $(pkg-config --cflags libtracefs) -c -o src/osnoise_hist.o src/osnoise_hist.c src/osnoise_hist.c:138:6: warning: variable 'bucket' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] 138 | if (data->bucket_size) | ^~~~~~~~~~~~~~~~~ src/osnoise_hist.c:149:6: note: uninitialized use occurs here 149 | if (bucket < entries) | ^~~~~~ src/osnoise_hist.c:138:2: note: remove the 'if' if its condition is always true 138 | if (data->bucket_size) | ^~~~~~~~~~~~~~~~~~~~~~ 139 | bucket = duration / data->bucket_size; src/osnoise_hist.c:132:12: note: initialize the variable 'bucket' to silence this warning 132 | int bucket; | ^ | = 0 1 warning generated. [...] clang -O -g -DVERSION=\"6.8.0-rc3\" -flto=auto -fexceptions -fstack-protector-strong -fasynchronous-unwind-tables -fstack-clash-protection -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS $(pkg-config --cflags libtracefs) -c -o src/timerlat_hist.o src/timerlat_hist.c src/timerlat_hist.c:181:6: warning: variable 'bucket' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] 181 | if (data->bucket_size) | ^~~~~~~~~~~~~~~~~ src/timerlat_hist.c:204:6: note: uninitialized use occurs here 204 | if (bucket < entries) | ^~~~~~ src/timerlat_hist.c:181:2: note: remove the 'if' if its condition is always true 181 | if (data->bucket_size) | ^~~~~~~~~~~~~~~~~~~~~~ 182 | bucket = latency / data->bucket_size; src/timerlat_hist.c:175:12: note: initialize the variable 'bucket' to silence this warning 175 | int bucket; | ^ | = 0 1 warning generated. This is a legit warning, but data->bucket_size is always > 0 (see timerlat_hist_parse_args()), so the if is not necessary. Remove the unneeded if (data->bucket_size) to avoid the warning. Link: https://lkml.kernel.org/r/6e1b1665cd99042ae705b3e0fc410858c4c42346.1707217097.git.bristot@kernel.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Bill Wendling Cc: Justin Stitt Cc: Donald Zickus Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode") Fixes: 829a6c0b5698 ("rtla/osnoise: Add the hist mode") Signed-off-by: Daniel Bristot de Oliveira

rtla/timerlat_hist: Add timerlat user-space support

2023-06-13T20:41:14+00:00

Add the support for running timerlat threads in user-space. In this mode, enabled with -u/--user-threads, timerlat dispatches user-space processes that will loop in the timerlat_fd, measuring the overhead for going to user-space and then returning to the kernel - in addition to the existing measurements. Here is one example of the tool's output with -u enabled: $ sudo timerlat hist -u -c 1-3 -d 600 # RTLA timerlat histogram # Time unit is microseconds (us) # Duration: 0 00:10:01 Index IRQ-001 Thr-001 Usr-001 IRQ-002 Thr-002 Usr-002 IRQ-003 Thr-003 Usr-003 0 477555 0 0 425287 0 0 474357 0 0 1 122385 7998 0 174616 1921 0 125412 3138 0 2 47 587376 492150 89 594717 447830 147 593463 454872 3 11 2549 101930 7 2682 145580 64 2530 138680 4 3 1954 2833 1 463 4917 11 548 4656 5 0 60 1037 0 138 1117 6 179 1130 6 0 26 1837 0 38 277 1 76 339 7 0 15 143 0 28 147 2 37 156 8 0 10 23 0 11 75 0 12 80 9 0 7 17 0 0 26 0 11 42 10 0 2 11 0 0 18 0 2 20 11 0 0 7 0 1 8 0 2 12 12 0 0 6 0 1 4 0 2 8 13 0 1 3 0 0 0 0 0 1 14 0 1 0 0 0 1 0 0 2 15 0 1 0 0 0 0 0 0 2 16 0 1 2 0 0 0 0 0 0 17 0 0 1 0 0 0 0 0 0 19 0 0 1 0 0 0 0 0 0 over: 0 0 0 0 0 0 0 0 0 count: 600001 600001 600001 600000 600000 600000 600000 600000 600000 min: 0 1 2 0 1 2 0 1 2 avg: 0 1 2 0 2 2 0 2 2 max: 4 16 19 4 12 14 7 12 15 The tuning setup like -p or -C work for the user-space threads as well. Link: https://lkml.kernel.org/r/b6a042d55003c4a67ff7dce28d96044b7044f00d.1686066600.git.bristot@kernel.org Cc: William White Cc: Jonathan Corbet Tested-by: Juri Lelli Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)

rtla: Start the tracers after creating all instances

2023-06-13T20:37:05+00:00

Group all start tracing after finishing creating all instances. The tracing instance starts first for the case of hitting a stop tracing while enabling other instances. The trace instance is the one with most valuable information. Link: https://lkml.kernel.org/r/67da7a703a56f75d7cd46568525145a65501a7e8.1686066600.git.bristot@kernel.org Cc: William White Cc: Jonathan Corbet Tested-by: Juri Lelli Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)

rtla/timerlat_hist: Add auto-analysis support

2023-06-13T20:35:46+00:00

Add auto-analysis to timerlat hist, including the --no-aa option to reduce overhead and --dump-task. --aa-only was not added as it is already on timerlat top. Link: https://lkml.kernel.org/r/c2693f47ee83e659a7723fed8035f5d2534f528e.1686066600.git.bristot@kernel.org Cc: William White Cc: Jonathan Corbet Tested-by: Juri Lelli Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)

rtla: Automatically move rtla to a house-keeping cpu

2023-06-13T20:30:13+00:00

When the user sets -c try to move rtla out of the , even without an -H option. This is useful to avoid having rtla interfering with the workload. This works by removing from rtla's current affinity. If rtla fails to move itself away it is not that of a problem as this is an automatic measure. Link: https://lkml.kernel.org/r/c54304d90c777310fb85a3e658d1449173759aab.1686066600.git.bristot@kernel.org Cc: William White Cc: Jonathan Corbet Tested-by: Juri Lelli Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)

rtla: Change monitored_cpus from char * to cpu_set_t

2023-06-13T20:28:56+00:00

Use a cpumask instead of a char *, reducing memory footprint and code. No functional change, and in preparation for auto house-keeping. Link: https://lkml.kernel.org/r/54c46293261d13cb1042d0314486539eeb45fe5d.1686066600.git.bristot@kernel.org Cc: William White Cc: Jonathan Corbet Tested-by: Juri Lelli Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)

rtla: Add --house-keeping option

2023-06-13T20:26:03+00:00

To avoid having rtla interfering with the measurement threads, add an option for the user to set the CPUs in which rtla should run. For instance: # rtla timerlat top -H 0 -c 1-7 Will place rtla in the CPU 0, while running the measurement threads in the CPU 1-7. Link: https://lkml.kernel.org/r/6a6c78a579a96ba8b02ae67ee1e0ba2cb5e03c4a.1686066600.git.bristot@kernel.org Cc: William White Cc: Jonathan Corbet Tested-by: Juri Lelli Suggested-by: Juri Lelli Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google)