Re: FreeBSD GSOC proposal in 2014

On Fri, Mar 14, 2014 at 01:07:48PM -0400, yan cui wrote:
> Thanks for the reply! I will get more information about KTR subsystem.
>

You can also look here:

http://people.freebsd.org/~kris/scaling/Help_my_system_is_slow.pdf

Wojciech

> 
> 
> 
> 
> 2014-03-14 3:02 GMT-04:00 Wojciech A. Koszek <wkoszek_at_freebsd.org>:
> 
> > On Thu, Mar 13, 2014 at 09:56:35PM -0400, yan cui wrote:
> > > Hi all,
> > >
> > >     I write this mail to make my question clear. I know witness can be
> > used
> > > to detect wrong lock order in the kernel. However, can it be used to do
> > > lock profiling (what I mean is to report the information such as which
> > > locks are most contended and print some related statistics such as
> > calling
> > > graph, etc)?
> > > In other words, is it enough to finish the task by porting witness to the
> > > pthread library?
> > >
> >
> > Yan,
> >
> > To my knowledge WITNESS is the only tool for lock order verification.
> >
> > For lock profiling in the FreeBSD kernel there's a KTR subsystem. KTR
> > mechanism is basically like syslog() in the user-space, but for the kernel.
> > KTR subsystem will receive messages from KTR API that is placed in the
> > FreeBSD kernel. Messages get stored on the list of some sort. List can be
> > exported to a file. File you can later analyze.
> >
> > Jeff wrote a Python app which can be used for pre-processing the KTR logs
> > from scheduler and protting them visually. Link:
> >
> > http://svnweb.freebsd.org/base/head/tools/sched/schedgraph.py
> >
> > Instead of porting witness to pthreads, maybe we could evaluate expanding
> > WITNESS to cover kern_umtx? This could prove to be more universal.
> >
> > Wojciech
> >
> > >
> > > 2014-03-13 19:19 GMT-04:00 yan cui <ccuiyyan_at_gmail.com>:
> > >
> > > > Hi all,
> > > >
> > > >     I have downloaded the newest FreeBSD-release kernel and scanned
> > some
> > > > codes.
> > > > Wonder to know whether the lock order verification and lock profiling
> > tool
> > > > mentioned in
> > > > the GSoC idea list is witness? Are there any other tools that needs to
> > > > look at in the FreeBSD kernel?
> > > >
> > > > Thanks, Yan
> > > >
> > > >
> > > > 2014-03-09 15:46 GMT-04:00 yan cui <ccuiyyan_at_gmail.com>:
> > > >
> > > > Hi All,
> > > >>
> > > >>      I am a student in Columbia University (Yan Cui), and want to join
> > > >> the FreeBSD GSOC 2014. After scanned the idea list posted online, I
> > think I
> > > >> am interested in
> > > >>  the idea titled "user space pthread mutex lock contention profiling
> > and
> > > >> lock order verification tools". I have several year experiences in
> > kernel
> > > >> and user locking and believe I can complete the task in time.
> > Currently, I
> > > >> wonder to know, before submitting an application on GSOC home page,
> > do I
> > > >> need to submit some documents in the community (to review?)
> > > >>
> > > >> Best Wishes!
> > > >> Yan
> > > >>
> > > >> --
> > > >> Think big; Dream impossible; Make it happen.
> > > >>
> > > >
> > > >
> > > >
> > > > --
> > > > Think big; Dream impossible; Make it happen.
> > > >
> > >
> > >
> > >
> > > --
> > > Think big; Dream impossible; Make it happen.
> > > _______________________________________________
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> > > http://lists.freebsd.org/mailman/listinfo/soc-status
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> >
> > --
> > Wojciech A. Koszek
> > wkoszek_at_FreeBSD.czest.pl
> > http://FreeBSD.czest.pl/~wkoszek/
> >
> 
> 
> 
> -- 
> Think big; Dream impossible; Make it happen.
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-- 
Wojciech A. Koszek
wkoszek_at_FreeBSD.czest.pl
http://FreeBSD.czest.pl/~wkoszek/