RE: Fwd: Systemtap support for disk i/o per pid

["Nguyen, Thang P" <thang.p.nguyen@intel.com>]

As for disk I/O, currently I am also adding more hooks into ioscheduler
tapset to track disk activities such as block I/O location and estimate
disk seek time.  Li, I can send you what I have, and see where to fit
(or perhaps consolidate) them if necessary.

Thang

-----Original Message-----
From: systemtap-owner@sourceware.org
[mailto:systemtap-owner@sourceware.org] On Behalf Of Li Guanglei
Sent: Sunday, May 28, 2006 11:39 PM
To: James Dickens
Cc: systemtap@sourceware.org
Subject: Re: Fwd: Systemtap support for disk i/o per pid

James Dickens ??:
> resending due to improper mime type on the original
> 
> it would be simpler in most cases to probe syscalls that are easily
> trackable to pid's though this won't give a totally accurate of IO
> because of caching, but it is the easiest, and safest. When you go to
> lower level kernel interfaces it becomes difficult to attiribute
> actions with the pid that caused them.
> 
> James Dickens
> uadmin.blogspot.com

Currently Systemtap could make you able to trace all syscalls by pid,
e.g:
   stap -e "probe addevent.syscall {} " -x pid
to trace both entry & return of all syscalls
or:
   stap -e "probe addevent.syscall {}" -c command

I am getting started with Jose to implement new hooks about IO system 
calls which could give more details other than the syscall name. And 
we are also trying to map systemcall to the io scheduler and scsi hooks.

- Li Guanglei