Re: [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 was found
> /lib/modules/4.10.0+/build/vmlinux with build id 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.
>
> Signed-off-by: Wang YanQing
Acked-by: Jiri Olsa
thanks,
jirka
> ---
> 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
Re: [PATCH] perf:util:dso: Using O_CLOEXEC in do_open
On Mon, Jan 15, 2018 at 10:45:06AM +0100, Jiri Olsa wrote:
> 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 was found
> > /lib/modules/4.10.0+/build/vmlinux with build id 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?
The problem is "perf report", isn't "perf kmem record",
see the above reproduction steps again.
The problem is "perf report" generates may open fds with
dso:do_open for symbol analysis, and "perf report" uses
popen to run another command "perf script", then the cmd
"perf script" will run out of "max open files".
Thanks.
>
> thanks,
> jirka
>
> >
> > Signed-off-by: Wang YanQing
> > ---
> > 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
Re: [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 was found
> /lib/modules/4.10.0+/build/vmlinux with build id 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
> ---
> 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
[PATCH] perf:util:dso: Using O_CLOEXEC in do_open
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 was found
/lib/modules/4.10.0+/build/vmlinux with build id 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.
Signed-off-by: Wang YanQing
---
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
