Min Sys Req's and CPU
rofthorax at gmail.com
Sat Sep 5 11:40:40 BST 2009
I second this.. BTW, is hyper-threading being on a bad idea?
I'm visiting my brother who works for Hughes Research lab, and does work
with linux and FreeBSD all the time. He says that one of the problems with
realtime kernels is the potential to have cores competing for resources,
resulting in dead lock. I read that this happens in processors such as the
Pentium 4 with hyper threading, as it tends to starve one thread of
resources (in the interest of making maximum use of both processors, also
termed as cache thrashing. Also there is some concern that such things can
happen in cores where memory is shared. I've thought, if the memory can be
locked by a processor in the L2 cache, could this improve performance. BTW
Intel discourages the use of hyper threading in applications not optimized
for it, which makes me wonder if there is a way to get a realtime kernel
either optimized for hyper-threading, or designed not avoid hyper-threading.
I'm thinking that in the case of the pentium-D's that it would be better to
avoid hyper-threading to guarantee that operations complete in a expected
amount of time.
Also, if I have a motherboard with APIC interrupt controllers, is the added
support for better interrupt scheduling going to help avoid a form of
resource starving/lock that leads to kernel freeze or deadlock.
I recall in my CS classes that if you force processes to allocate resources
by the same method that is used in post offices to order people into lines
without literally forming a line (by taking a number), you can avoid greedy
resource allocation that leads to deadlock by resource holding. I don't know
what this method is, but it seemed convincing to me as a way of avoiding
these lock-ups at the time.
I know this sounds like I'm searching for a answer to this Xrun problem, but
the solution may be better to suggest a way of working when making
compositions with Jack and the other audio applications, like say being able
to layer (or automate the layering) of tracks using rosegarden and ardour. I
know some people care more about performance with Jack, but with the use of
ardour, it would be possible to complete work with poorly performing audio
applications, like ZynAddSubFx which can bring a CPU to it's knees quite
easily. I'm personally stuck on trying to get rosegarden to play and ardour
to record in synchronization. I've tried lots of things with no success.. If
I find the solution, I'll post it on youtube where others can get the answer
without having to come here and plug the listserv for information. One way
to reduce questions is to make information resources more accessible. A
listserv is nice in one way of providing help but it isn't very effective at
reducing the frequency of common questions, a FAQ isn't very helpful, how
about a video FAQ?
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