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SubjectRe: [PATCH] perf:util:dso: Using O_CLOEXEC in do_open
On Mon, Jan 15, 2018 at 01:04:48PM +0800, Wang YanQing wrote:
> I meet strange behavior with below commands on my gentoo box:
> 1:perf kmem record
> 2:CTRL-C to stop 1
> 3:perf report
> 4:"Enter", "Enter", "Run scripts for all samples",
> "event_analyzing_sample".
>
> Then perf report:
> "
> No kallsyms or vmlinux with build-id xxxx was found
> /lib/modules/4.10.0+/build/vmlinux with build id xxxx not found,
> continuing without symbols
> ".
>
> It is strange because I am sure /lib/modules/4.10.0+/build/vmlinux
> is right for perf.data.
>
> After digging, I find out the reason is "perf report" generates many
> open fds, then "script_browse" uses popen to run "perf script" which
> run out of open files. The gentoo box has a small default value for
> "max open files", 1024. Yes, "ulimit -n " with a bigger number could
> fix it, but I think that using O_CLOEXEC in do_open is a better way.

that seems right.. so why does kmem record open those
files before calling cmd_record? should that be fixed?

thanks,
jirka

>
> Signed-off-by: Wang YanQing <udknight@gmail.com>
> ---
> tools/perf/util/dso.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
> index d5b6f7f..36ef45b 100644
> --- a/tools/perf/util/dso.c
> +++ b/tools/perf/util/dso.c
> @@ -446,7 +446,7 @@ static int do_open(char *name)
> char sbuf[STRERR_BUFSIZE];
>
> do {
> - fd = open(name, O_RDONLY);
> + fd = open(name, O_RDONLY|O_CLOEXEC);
> if (fd >= 0)
> return fd;
>
> --
> 1.8.5.6.2.g3d8a54e.dirty

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