On Tue, Jul 9, 2013 at 8:37 AM, Sami Kerola <kerolasa@xxxxxx> wrote: > On 8 July 2013 21:21, Kay Sievers <kay@xxxxxxxx> wrote: >> On Sun, Jul 7, 2013 at 9:54 PM, Sami Kerola <kerolasa@xxxxxx> wrote: >>> At the moment util-linux command are not threading, which means they can >>> safely use thread-unsafe IO system calls which should make printing >>> quicker. >> >> Do you have numbers about the assumption that this will produce better >> results on Linux? >> >> Uncontended mutexes/futexes on Linux probably might not really show >> up. Maybe in inner loops, not sure. Would be nice to know ... > > I did not do much testing, and to be honest results were slightly > disappointing. With simple 'time command < big_file' most of the > commands did not show measurable difference, but as a junior > programmer I thought the _unlocked would be beneficial for single > thread programs. As such assumptions are not preferred I will set up > some sort of test, which will try to accomplish what is the difference > of each locked vs _unlocked function call with various output sizes. > Assuming I get the test right it should not be a big deal to run it on > various systems I have access. Here is a bit of the background, which explains a bit why uncontended futexes (which is always the case in single-threaded programs) might not really make a difference on common Linux architectures. They will not even involve the kernel, just a simple instruction: http://lwn.net/Articles/360699/ Kay -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
