Date: Fri, 14 Mar 2014 13:07:48 -0400 From: yan cui <ccuiyyan@gmail.com> To: "Wojciech A. Koszek" <wkoszek@freebsd.org> Cc: freebsd-hackers@freebsd.org, freebsd-current@freebsd.org, soc-status@freebsd.org Subject: Re: FreeBSD GSOC proposal in 2014 Message-ID: <CAAVq3rknW1Hry2s_Ztpwp0vNrQbRjjPickdiL1Gb6DAY=PQVyQ@mail.gmail.com> In-Reply-To: <20140314070218.GA37327@FreeBSD.org> References: <CAAVq3rkyqmu6fKL9jFX6NmwaiB794H5fN_Ec79GYG39GHfh2Ow@mail.gmail.com> <CAAVq3rmpXSYDbHUys7JQztYRU1qB2OCF%2Bt8HXoZMBbgXznCG2w@mail.gmail.com> <CAAVq3rmQVZqvmF7bg0=9oHBrUDMegvmREKPe4E2RCfQ=3yxo9w@mail.gmail.com> <20140314070218.GA37327@FreeBSD.org>
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Thanks for the reply! I will get more information about KTR subsystem. 2014-03-14 3:02 GMT-04:00 Wojciech A. Koszek <wkoszek@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@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@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. > > _______________________________________________ > > soc-status@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/soc-status > > To unsubscribe, send any mail to "soc-status-unsubscribe@freebsd.org" > > -- > Wojciech A. Koszek > wkoszek@FreeBSD.czest.pl > http://FreeBSD.czest.pl/~wkoszek/ > -- Think big; Dream impossible; Make it happen.
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