From c4a852635eddcf4130a93e687bc7b120b19fd1b7 Mon Sep 17 00:00:00 2001 From: Yang Jihong Date: Fri, 13 Oct 2023 07:59:45 +0000 Subject: perf data: Increase RLIMIT_NOFILE limit when open too many files in perf_data__create_dir() If using parallel threads to collect data, perf record needs at least 6 fds per CPU. (one for sys_perf_event_open, four for pipe msg and ack of the pipe, see record__thread_data_open_pipes(), and one for open perf.data.XXX) For an environment with more than 100 cores, if perf record uses both `-a` and `--threads` options, it is easy to exceed the upper limit of the file descriptor number, when we run out of them try to increase the limits. Before: $ ulimit -n 1024 $ lscpu | grep 'On-line CPU(s)' On-line CPU(s) list: 0-159 $ perf record --threads -a sleep 1 Failed to create data directory: Too many open files After: $ ulimit -n 1024 $ lscpu | grep 'On-line CPU(s)' On-line CPU(s) list: 0-159 $ perf record --threads -a sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.394 MB perf.data (1576 samples) ] Signed-off-by: Yang Jihong Acked-by: Namhyung Kim Link: https://lore.kernel.org/r/20231013075945.698874-1-yangjihong1@huawei.com Signed-off-by: Namhyung Kim --- tools/perf/util/data.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'tools') diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c index fc16299c915f..098f9e3bb2e7 100644 --- a/tools/perf/util/data.c +++ b/tools/perf/util/data.c @@ -17,6 +17,7 @@ #include "util.h" // rm_rf_perf_data() #include "debug.h" #include "header.h" +#include "evsel.h" #include static void close_dir(struct perf_data_file *files, int nr) @@ -35,6 +36,7 @@ void perf_data__close_dir(struct perf_data *data) int perf_data__create_dir(struct perf_data *data, int nr) { + enum rlimit_action set_rlimit = NO_CHANGE; struct perf_data_file *files = NULL; int i, ret; @@ -54,11 +56,21 @@ int perf_data__create_dir(struct perf_data *data, int nr) goto out_err; } +retry_open: ret = open(file->path, O_RDWR|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR); if (ret < 0) { + /* + * If using parallel threads to collect data, + * perf record needs at least 6 fds per CPU. + * When we run out of them try to increase the limits. + */ + if (errno == EMFILE && evsel__increase_rlimit(&set_rlimit)) + goto retry_open; + ret = -errno; goto out_err; } + set_rlimit = NO_CHANGE; file->fd = ret; } -- cgit