[lkml]   [2001]   [Dec]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: SMP/cc Cluster description
At 06:36 PM 12/4/01 -0800, David S. Miller wrote:
>What is the difference between your messages and spin locks?
>Both seem to shuffle between cpus anytime anything interesting
>In the spinlock case, I can thread out the locks in the page cache
>hash table so that the shuffling is reduced. In the message case, I
>always have to talk to someone.

While what I'm about to say has little bearing on the SMP/cc case: one
significant advantage of messages over spinlocks is being able to assign
priority with low overhead in the quick-response real-time multi-CPU
arena. I worked with a cluster of up to 14 CPUs using something very much
like NUMA in which task scheduling used a set of prioritized message
queues. The system I worked on was designed to break transaction-oriented
tasks into a string of "work units" each of which could be processed very
quickly -- on the order of three milliseconds or less. (The limit of 14
CPUs was set by the hardware used to implement the main system bus.)

I bring this up only because I have never seen a spinlock system that dealt
with priority issues very well when under heavy load.

OK, I've said my piece, now I'll sit back and continue to watch your


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:13    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean