So I am stuck Grrr
Anyone with ideas on how I can understand why "my packages" are causing issues, while apparently, "perl-provided" packages such as LWP::UserAgent dont? On Tue, Sep 8, 2009 at 5:58 PM, Shachar Shemesh <[email protected]> wrote: > Noam Rathaus wrote: > > The only obvious one is that read() shown under strace, takes a significant > more time on the new machine than the old one > > You can split the difference between the platforms into three groups: > Time spent in the kernel (0.032 seconds) > Time spent in userspace (7.761 seconds) > Time spent sleeping or otherwise scheduled out (7.287 seconds) > > strace -c goes a long way, and works very hard, to show us information that > is not useful to us. It counts CPU time spent in system calls, not actual > wall time. What may provide a more useful output in this case is -T, which > will also count time in which the process was sleeping inside a system call > (which accounts for about half the slowdown). > > The second half of the slowdown, the one done in user space, is more > difficult to trace without the sources (i.e. - the perl sources). valgrind > has a module for detecting what causes a slowdown, but I doubt Noam wants to > start analyzing perl to figure out what the different areas actually mean. > > > Shachar > > > On Tue, Sep 8, 2009 at 5:43 PM, Shachar Shemesh <[email protected]>wrote: > >> Noam Meltzer wrote: >> >> the time output does looks like you have higher cpu usage for some reason, >> so i agree with Shachar on this. >> >> you can also try to pinpoint the place the cpu is spent. >> strace and/or ltrace with the '-f -c' flags can help. >> >> I'm not sure about ltrace, but strace will not help. Most of the time is >> spent in user space, not in the kernel. >> >> Strace may help if the problem is time spent in another process (i.e. - >> while the main process is sleeping), but it seems Noam has already tried >> that one and failed to spot any obvious candidates. >> >> Shachar >> >> >> >> >> On Tue, Sep 8, 2009 at 5:24 PM, Shachar Shemesh <[email protected]>wrote: >> >>> Noam Rathaus wrote: >>> >>> I know the time difference doesn't look too bad, but take a bigger code >>> set: >>> >>> Fast: >>> real 0m1.682s >>> user 0m1.584s >>> sys 0m0.064s >>> >>> Slow: >>> real 0m16.730s >>> user 0m9.345s >>> sys 0m0.096s >>> >>> These times spell "CPU intensive". Does your library do anything >>> special? If you try to import a dummy library, does this still happen? >>> >>> Shachar >>> >>> -- >>> Shachar Shemesh >>> Lingnu Open Source Consulting Ltd.http://www.lingnu.com >>> >>> >> >> >> -- >> Shachar Shemesh >> Lingnu Open Source Consulting Ltd.http://www.lingnu.com >> >> > > > -- > Shachar Shemesh > Lingnu Open Source Consulting Ltd.http://www.lingnu.com > >
_______________________________________________ Linux-il mailing list [email protected] http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
