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perf data: Increase RLIMIT_NOFILE limit when open too many files in perf_data__create_dir()

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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 <yangjihong1@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20231013075945.698874-1-yangjihong1@huawei.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Yang Jihong 2023-10-13 07:59:45 +00:00 committed by Namhyung Kim
parent 3f8b6e5b11
commit c4a852635e
1 changed files with 12 additions and 0 deletions
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12
tools/perf/util/data.c
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@ -17,6 +17,7 @@
#include "util.h" // rm_rf_perf_data()
#include "debug.h"
#include "header.h"
#include "evsel.h"
#include <internal/lib.h>
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;
}