On 01/07/2010 01:30 AM, Leyendecker, Robert wrote: >>> How about -m (mlockall) as well? >> Hmm, I think that this one is less obvious. Apparently, there are >> a bunch of different opinions on mlockall(). I once heard, for >> example, the opinion that mlockall() may - under some conditions - >> introduce a performance penalty, but I did not verify that. Many >> real-time systems do not have a "swap" line in /etc/fstab; >> mlockall() is not needed in such systems. In addition, most today's >> systems have so much RAM that swapping became a rather rare event. >> I hope some other RT-ers who are more knowledgeable about memory >> management and swapping can comment on this. > I have found mlockall() necessary. I alloc very large buffers for > transmitting and capturing hundreds of voip streams. In my testing, > if I don't mlockall() mostly following the advice on the rt-wiki > (thanks for this life saver) network rt performance is unacceptable, > jitter is 10X - 50X worse on my system. File system activity renders > the system choppy and sluggish. All my memory is nailed up and > preloaded where possible before I pull the trigger. I run on standard > FC distro (with most services turned off). Getting good performance > on a standard distro is amazing to me. > Our test team has discovered that they get good network performance > while simultaneously running wireshark and other apps like VNC. I > think audio guys run huge x apps and full blown distros, while > running 12+ channels of raw audio to disk. I can't see how they do it > without mlock. > [..] Yes, of course. No one wants to drop the -m option. It was only the question whether we include it into the new -S (equals -a -t -n -d plus same priority on all) option which would make it impossible to run -S without -m. In case it is decided not to include -m, you would need to specify it separately, such as, for example cyclictest -Sp99 -m I would guess that this is acceptable, isn't it? Carsten. -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
