Systemtap support for disk i/o per pid

Systemtap support for disk i/o per pid

[R Blundell]

Hello, this is my first post to the mailing list. Does or will systemtap 
support "per pid" disk i/o accounting/details?  I could not find any 
mention of this specifically on the website, papers, etc.

Thank you
Rick

Re: Systemtap support for disk i/o per pid

[Li Guanglei]

R Blundell ??:
> Hello, this is my first post to the mailing list. Does or will systemtap 
> support "per pid" disk i/o accounting/details?  I could not find any 
> mention of this specifically on the website, papers, etc.
> 
> Thank you
> Rick
Currently systemtap could be able to trace the io scheduler activities 
and scsi activities. You could use "man lket" to get more details.

Some event hooks in these two categories could be filtered by pid. But 
  you can just trace all of them and later filter by pid in user space.

Fwd: Systemtap support for disk i/o per pid

[James Dickens]

resending due to improper mime type on the original


---------- Forwarded message ----------
From: James Dickens <jamesd.wi@gmail.com>
Date: May 28, 2006 2:08 PM
Subject: Re: Systemtap support for disk i/o per pid
To: Li Guanglei <guanglei@cn.ibm.com>
Cc: R Blundell <rickb@rapidvps.com>, systemtap@sourceware.org



On 5/27/06, Li Guanglei <guanglei@cn.ibm.com> wrote:
>  R Blundell ??:
> > Hello, this is my first post to the mailing list. Does or will systemtap
> > support "per pid" disk i/o accounting/details?  I could not find any
> > mention of this specifically on the website, papers, etc.
> >
> > Thank you
> > Rick
> Currently systemtap could be able to trace the io scheduler activities
> and scsi activities. You could use "man lket" to get more details.
>
> Some event hooks in these two categories could be filtered by pid. But
>   you can just trace all of them and later filter by pid in user space.
>
>

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

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

[Li Guanglei]

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

Systemtap support for disk i/o per pid

[R Blundell]

Hello, this is my first post to the mailing list. Does or will systemtap 
support "per pid" disk i/o accounting/details?  I could not find any 
mention of this specifically on the website, papers, etc.

Thank you
Rick