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From: Aniruddha S. <sh...@cs...> - 2005-11-11 04:05:14
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On Wed, 9 Nov 2005, Josef Weidendorfer wrote: Hi, I am running Callgrind with the options -v --log-file=summary --simulate-cache=yes --simulate-hwpref=yes --cacheuse=yes. The summary log file contains the lines: Prefetch Up: 0 Prefetch Down: 0 What do these lines mean? From what I understand, --simulate-hwpref=yes simulates a hardware prefetcher, as is found in the Intel Pentium 4 processor. Also, does --cacheuse=yes collect cache line utilization statistics i.e. what percentage of a line is utilized after being brought into cache and before being evicted from the cache? Where can this information viewed? Thanks, Aniruddha > On Wednesday 09 November 2005 04:03, you wrote: > > I want to speedup the simulation by specifying that a certain code segment > > not be profiled while the remainder of the code be profiled. > > Ah, you always should say what you want to achieve when asking a question > on the mailing list. > > A speedup can only be achieved by simplified instrumentation. In > Cachegrind/Callgrind, this would mean that the cache simulator is not > feeded with the memory access stream. And this would make the whole > cache simulation go wrong. > > So you do not want to change instrumentation with Cachegrind/Callgrind, > if you are interested in any cache misses/hits. > > With Callgrind, the default is to not to do cache simulation. But Callgrind > has an additional slowdown because of call graph tracing. So this is not > the way for a speedup. > > But you can temporarily switch of instrumentation for all the code which is > run. Then, if you switch it on later on, you have to prepared that there > will be cache misses which would not happen in reality. But an approximation > of the real cache state usually should be reached a few million memory accesses > later (depending on the application). Thus, depending on cache size, you will > have a fixed number of cache misses more, but this number disappears in > noise level after some time. > > To start without instrumentation (same as valgrind --tool=none...), start > callgrind with "callgrind --instr-atstart=no ...", and run > a "callgrind_control -i on" afterwards, or use CALLGRIND_START_INSTRUMENTATION() > from $prefix/include/valgrind/callgrind.h to switch instrumentation on > programatically. > > Josef > > > > > Will this > > really speedup the simulation? Does the --toggle-collect=<func> option > > ensure that functions called from within <func> are not profiled? > > > > Cheers, > > Aniruddha > > > > ----- Original Message ----- > > From: "Josef Weidendorfer" <Jos...@gm...> > > To: <val...@li...> > > Sent: Saturday, November 05, 2005 5:04 PM > > Subject: [SPAM] Re: [Valgrind-users] Selective profiling with Cachegrind > > > > > > > On Saturday 05 November 2005 21:19, Aniruddha Shet wrote: > > >> Hi, > > >> > > >> Does Cachegrind allow you to specify that certain functions not be > > >> profiled? > > >> In other words, is there a way to turn on and off profiling in certain > > >> code > > >> segments? > > > > > > Cachegrind gives you self cost of functions, so why not simply ignore the > > > functions in the output you do not want to be profiled? > > > > > > Or check out the callgrind tool and the --toggle-collect=<func> option. > > > It will toggle the collection state when entering or leaving a given > > > function. > > > > > > Josef > > > > > > > > > > > > ------------------------------------------------------- > > > SF.Net email is sponsored by: > > > Tame your development challenges with Apache's Geronimo App Server. > > > Download > > > it for free - -and be entered to win a 42" plasma tv or your very own > > > Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php > > > _______________________________________________ > > > Valgrind-users mailing list > > > Val...@li... > > > https://lists.sourceforge.net/lists/listinfo/valgrind-users > > > > > > > > > > ------------------------------------------------------- > SF.Net email is sponsored by: > Tame your development challenges with Apache's Geronimo App Server. Download > it for free - -and be entered to win a 42" plasma tv or your very own > Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php > _______________________________________________ > Valgrind-users mailing list > Val...@li... > https://lists.sourceforge.net/lists/listinfo/valgrind-users > -- ----------------------------------------------------------------------------------------- Aniruddha G. Shet | Project webpage: http://forge-fre.ornl.gov/molar/index.html Graduate Research Associate | Project webpage: http://www.cs.unm.edu/~fastos Dept. of Comp. Sci. & Engg | Personal webpage: http://www.cse.ohio-state.edu/~shet The Ohio State University | Office: DL 474 2015 Neil Avenue | Phone: +1 (614) 292 7036 Columbus OH 43210-1277 | Cell: +1 (614) 446 1630 ----------------------------------------------------------------------------------------- |