From: Vara Prasad <prasadav@us.ibm.com>
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: systemtap@sources.redhat.com
Subject: Re: [Bug translator/3534] New: support wildcarded linenumber probe syntax
Date: Fri, 17 Nov 2006 06:25:00 -0000 [thread overview]
Message-ID: <455D5208.6060307@us.ibm.com> (raw)
In-Reply-To: <20061117014448.3534.fche@redhat.com>
fche at redhat dot com wrote:
>Idea: probe kernel.function("function@*:*") would put a probe at
>every ~instruction (line record) boundary within the function.
>This would allow a script to collect detailed profile/coverage
>information (albeit at a considerable trapping overhead cost).
>
>
>
I am not sure i followed your idea. For example if I have the following
function
If i specify probe
kernel.statement("get_symbol_offset@kernel.kallsyms.c:*"), the above
feature will place probes for every instruction of an executable
statement in this case line nos 139, 145,146 and 148. Did i get your
proposal correct?
If i got your above idea correct, is this proposal is to support tracing
of a function without tracing other functions it calls. In other words
i am trying to understand what is the underlying motivation for this
proposal.
132
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l132>
static unsigned int get_symbol_offset(unsigned long pos)
133
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l133>
{
134
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l134>
u8 *name;
135
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l135>
int i;
136
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l136>
137
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l137>
/* use the closest marker we have. We have markers every 256 positions,
138
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l138>
* so that should be close enough */
139
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l139>
name = &kallsyms_names[ kallsyms_markers[pos>>8] ];
140
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l140>
141
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l141>
/* sequentially scan all the symbols up to the point we're searching for.
142
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l142>
* Every symbol is stored in a [<len>][<len> bytes of data] format, so we
143
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l143>
* just need to add the len to the current pointer for every symbol we
144
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l144>
* wish to skip */
145
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l145>
for(i = 0; i < (pos&0xFF); i++)
146
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l146>
name = name + (*name) + 1;
147
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l147>
148
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l148>
return name - kallsyms_names;
149
<http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;h=eeac3e313b2bfa41f26a4ccd9235232593fb947c;hb=1b9bb3c14c60324b54645ffefbe6d270f9fd191c;f=kernel/kallsyms.c#l149>
}
bye,
Vara Prasad
next prev parent reply other threads:[~2006-11-17 6:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-17 1:45 fche at redhat dot com
2006-11-17 6:09 ` [Bug translator/3534] " fche at redhat dot com
2006-11-17 6:25 ` Vara Prasad [this message]
2006-11-17 18:25 ` joshua dot i dot stone at intel dot com
2006-11-17 22:27 ` fche at redhat dot com
2008-01-21 14:46 ` fche at redhat dot com
Reply instructions:
You may reply publicly 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=455D5208.6060307@us.ibm.com \
--to=prasadav@us.ibm.com \
--cc=fche@redhat.com \
--cc=systemtap@sources.redhat.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).