Linux-Trace-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Vincent Donnefort <vincent.donnefort@arm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: <linux-trace-devel@vger.kernel.org>
Subject: Re: [PATCH 2/2] trace-cmd: Add an option to set saved_cmdlines_size
Date: Tue, 12 Nov 2019 12:03:15 +0000
Message-ID: <20191112120314.GA41032@e120877-lin.cambridge.arm.com> (raw)
In-Reply-To: <20191111175203.252cc439@gandalf.local.home>

On Mon, Nov 11, 2019 at 05:52:03PM -0500, Steven Rostedt wrote:
> On Thu,  7 Nov 2019 10:51:06 +0000
> vincent.donnefort@arm.com wrote:
>
> > From: Vincent Donnefort <vincent.donnefort@arm.com>
> >
> > The tracing file saved_cmdlines_size allows setting the number of entries
> > that saved_cmdlines will contain. The latter is then dumped into the
> > trace.dat file to map PIDs with comm. The default value is 128.
> >
> > Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
> >
> > diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> > index 7260d27..a4e10a4 100644
> > --- a/tracecmd/trace-record.c
> > +++ b/tracecmd/trace-record.c
> > @@ -229,6 +229,7 @@ struct common_record_context {
> >     int topt;
> >     int do_child;
> >     int run_command;
> > +   int saved_cmdlines_size;
> >  };
> >
> >  static void add_reset_file(const char *file, const char *val, int prio)
> > @@ -1810,6 +1811,39 @@ static void set_options(void)
> >     }
> >  }
> >
> > +static void set_saved_cmdlines_size(struct common_record_context *ctx)
> > +{
> > +   char *path, *str;
> > +   int fd, len, ret;
> > +
> > +   if (!ctx->saved_cmdlines_size)
> > +           return;
> > +
> > +   path = tracecmd_get_tracing_file("saved_cmdlines_size");
> > +   if (!path)
> > +           goto err;
> > +
> > +   reset_save_file(path, RESET_DEFAULT_PRIO);
> > +
> > +   fd = open(path, O_WRONLY);
> > +   tracecmd_put_tracing_file(path);
> > +   if (fd < 0)
> > +           goto err;
> > +
> > +   len = asprintf(&str, "%d", ctx->saved_cmdlines_size);
> > +   if (len < 0)
> > +           die("%s couldn't allocate memory", __func__);
> > +
> > +   if (write(fd, str, len) > 0)
> > +           ret = 0;
> > +
> > +   close(fd);
> > +   free(str);
> > +err:
> > +   if (ret)
> > +           warning("Couldn't set saved_cmdlines_size");
> > +}
> > +
> >  static int trace_check_file_exists(struct buffer_instance *instance, char *file)
> >  {
> >     struct stat st;
> > @@ -5480,7 +5514,7 @@ static void parse_record_options(int argc,
> >             if (IS_EXTRACT(ctx))
> >                     opts = "+haf:Fp:co:O:sr:g:l:n:P:N:tb:B:ksiT";
> >             else
> > -                   opts = "+hae:f:FA:p:cC:dDGo:O:s:r:vg:l:n:P:N:tb:R:B:ksSiTm:M:H:q";
> > +                   opts = "+hae:f:FA:p:cC:dDGo:O:s:r:vg:l:n:P:N:tb:R:B:kK:sSiTm:M:H:qK";
> >             c = getopt_long (argc-1, argv+1, opts, long_options, &option_index);
> >             if (c == -1)
> >                     break;
> > @@ -5741,6 +5775,9 @@ static void parse_record_options(int argc,
> >             case 'k':
> >                     keep = 1;
> >                     break;
> > +           case 'K':
> > +                   ctx->saved_cmdlines_size = atoi(optarg);
> > +                   break;
>
> Perhaps we should make this a long variable --cmdline-size(?), and not
> yet give it a short option.

Hi Steve,

Thank you for your review. I also thought that we could avoid having a new
option and try to write /proc/sys/kernel/threads-max into saved_cmdlines_size,
before recording the trace. Do you think that would be a more suitable
solution?

--
Vincent

>
> >             case 'i':
> >                     ignore_event_not_found = 1;
> >                     break;
> > @@ -5990,6 +6027,7 @@ static void record_trace(int argc, char **argv,
> >                     enable_events(instance);
> >     }
> >
> > +   set_saved_cmdlines_size(ctx);
> >     set_buffer_size();
> >     update_plugins(type);
> >     set_options();
> > diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
> > index b5788f7..ddfb480 100644
> > --- a/tracecmd/trace-usage.c
> > +++ b/tracecmd/trace-usage.c
> > @@ -47,6 +47,7 @@ static struct usage_help usage_help[] = {
> >             "          -b change kernel buffersize (in kilobytes per CPU)\n"
> >             "          -B create sub buffer and following events will be enabled here\n"
> >             "          -k do not reset the buffers after tracing.\n"
> > +           "          -K change kernel saved_cmdlines_size\n"
>
> We would also want to update the man pages too.
>
> Thanks!
>
> -- Steve
>
> >             "          -i do not fail if an event is not found\n"
> >             "          -q print no output to the screen\n"
> >             "          --quiet print no output to the screen\n"
>
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

  reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-07 10:51 [PATCH 1/2] trace-cmd: Enable kptr_restrict vincent.donnefort
2019-11-07 10:51 ` [PATCH 2/2] trace-cmd: Add an option to set saved_cmdlines_size vincent.donnefort
2019-11-11 22:52   ` Steven Rostedt
2019-11-12 12:03     ` Vincent Donnefort [this message]
2019-11-12 14:40       ` Steven Rostedt
2019-11-12 19:01         ` Vincent Donnefort
2019-11-12 19:09           ` Steven Rostedt
2019-11-13 12:14             ` [PATCH v2 1/2] trace-cmd: Enable kptr_restrict vincent.donnefort
2019-11-13 12:14               ` [PATCH v2 2/2] trace-cmd: Add an option to set saved_cmdlines_size vincent.donnefort
2019-11-13 12:27             ` [PATCH " Vincent Donnefort
2019-11-13 15:08               ` Steven Rostedt
2019-11-12 12:03     ` [PATCH v2 1/2] trace-cmd: Enable kptr_restrict vincent.donnefort
2019-11-12 12:03       ` [PATCH v2 2/2] trace-cmd: Add an option to set saved_cmdlines_size vincent.donnefort
2019-11-11 22:47 ` [PATCH 1/2] trace-cmd: Enable kptr_restrict Steven Rostedt

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191112120314.GA41032@e120877-lin.cambridge.arm.com \
    --to=vincent.donnefort@arm.com \
    --cc=linux-trace-devel@vger.kernel.org \
    --cc=rostedt@goodmis.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Trace-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-trace-devel/0 linux-trace-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-trace-devel linux-trace-devel/ https://lore.kernel.org/linux-trace-devel \
		linux-trace-devel@vger.kernel.org
	public-inbox-index linux-trace-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-trace-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git