65 messages in org.freebsd.freebsd-smpRe: SMP meeting summary| From | Sent On | Attachments |
|---|---|---|
| Jason Evans | Jun 24, 2000 11:56 pm | |
| Daniel Eischen | Jun 25, 2000 6:58 am | |
| Terry Lambert | Jun 25, 2000 10:12 am | |
| Terry Lambert | Jun 25, 2000 10:36 am | |
| Julian Elischer | Jun 25, 2000 10:41 am | |
| Poul-Henning Kamp | Jun 25, 2000 11:07 am | |
| Nate Williams | Jun 25, 2000 9:41 pm | |
| Frank Mayhar | Jun 25, 2000 11:27 pm | |
| Frank Mayhar | Jun 25, 2000 11:31 pm | |
| Luoqi Chen | Jun 26, 2000 9:46 am | |
| Arun Sharma | Jun 26, 2000 9:47 am | |
| Jason Evans | Jun 26, 2000 11:06 am | |
| Matthew Dillon | Jun 26, 2000 12:26 pm | |
| Matthew Dillon | Jun 26, 2000 12:48 pm | |
| John Sconiers | Jun 26, 2000 12:56 pm | |
| Matthew Dillon | Jun 26, 2000 1:07 pm | |
| Luoqi Chen | Jun 26, 2000 1:13 pm | |
| Doug Rabson | Jun 26, 2000 1:26 pm | |
| Jason Evans | Jun 26, 2000 2:56 pm | |
| Jason Evans | Jun 26, 2000 3:14 pm | |
| Daniel Eischen | Jun 26, 2000 4:59 pm | |
| Luoqi Chen | Jun 26, 2000 7:14 pm | |
| Jason Evans | Jun 26, 2000 7:55 pm | |
| Joe Eykholt | Jun 26, 2000 8:09 pm | |
| Greg Lehey | Jun 27, 2000 8:00 pm | |
| Jason Evans | Jun 27, 2000 8:25 pm | |
| Daniel Eischen | Jun 27, 2000 8:26 pm | |
| Greg Lehey | Jun 27, 2000 9:59 pm | |
| Greg Lehey | Jun 27, 2000 10:11 pm | |
| Terry Lambert | Jun 28, 2000 4:15 pm | |
| Terry Lambert | Jun 28, 2000 4:18 pm | |
| Terry Lambert | Jun 28, 2000 4:37 pm | |
| Terry Lambert | Jun 28, 2000 4:51 pm | |
| Arun Sharma | Jun 28, 2000 9:43 pm | |
| Greg Lehey | Jul 2, 2000 7:15 pm | |
| Daniel Eischen | Jul 3, 2000 3:23 am | |
| Greg Lehey | Jul 3, 2000 3:30 am | |
| Jeroen C. van Gelderen | Jul 3, 2000 7:55 am | |
| Chuck Paterson | Jul 3, 2000 8:28 am | |
| Chuck Paterson | Jul 3, 2000 8:47 am | |
| Frank Mayhar | Jul 3, 2000 8:49 am | |
| Greg Lehey | Jul 3, 2000 4:08 pm | |
| David Scheidt | Jul 3, 2000 4:35 pm | |
| Joe Eykholt | Jul 3, 2000 4:47 pm | |
| Greg Lehey | Jul 3, 2000 4:52 pm | |
| Joe Eykholt | Jul 3, 2000 4:58 pm | |
| Greg Lehey | Jul 3, 2000 5:26 pm | |
| Joe Eykholt | Jul 3, 2000 5:41 pm | |
| Chuck Paterson | Jul 3, 2000 7:17 pm | |
| Daniel Eischen | Jul 3, 2000 7:25 pm | |
| Daniel Eischen | Jul 3, 2000 7:35 pm | |
| Greg Lehey | Jul 3, 2000 7:39 pm | |
| Daniel Eischen | Jul 3, 2000 7:41 pm | |
| Chuck Paterson | Jul 3, 2000 8:40 pm | |
| Alfred Perlstein | Jul 3, 2000 10:08 pm | |
| Greg Lehey | Jul 3, 2000 10:37 pm | |
| Peter Wemm | Jul 4, 2000 2:43 pm | |
| Greg Lehey | Jul 4, 2000 3:58 pm | |
| Peter Wemm | Jul 4, 2000 4:06 pm | |
| Terry Lambert | Jul 5, 2000 3:38 pm | |
| Terry Lambert | Jul 5, 2000 4:00 pm | |
| Terry Lambert | Jul 5, 2000 4:06 pm | |
| Terry Lambert | Jul 5, 2000 4:10 pm | |
| Alfred Perlstein | Jul 5, 2000 4:29 pm | |
| Terry Lambert | Jul 6, 2000 4:50 pm |
| Subject: | Re: SMP meeting summary | |
|---|---|---|
| From: | Alfred Perlstein (bri...@wintelcom.net) | |
| Date: | Jul 5, 2000 4:29:04 pm | |
| List: | org.freebsd.freebsd-smp | |
* Terry Lambert <tlam...@primenet.com> [000705 16:11] wrote:
The idea is that for spin or spin-then-sleep mutexes (very short hold time) is that since you won't have as many processes as cpus contending (and when you do it's ok) that the mutual exclusion is so short lived that by the time the next 'thundering' process is actually given the CPU, the likelyhood is that other processes have already aquired _and_ released the spinlock making it more than likely that the reasource is free.
The idea is that the a quantum is actually so great that there's little chance of one of the wake_all processes colliding on the lock.
This is a bogus idea, both in the case of a large number of processors, and in quantum ownership case.
You are correct in that it's bogus for _large_ number of processors, but for small numbers it makes a lot of sense. It would work nicely if one could attempt to schedule the processes in order that they were unblocked.
Even on system with a signifigant amount of CPUs, sssuming the system is busy, then between actually scheduling these thundering processes on other CPUs and having them run there will be enough time to avoid another pileup on the mutex.
If the CPUs are not busy and collisions occur, well then the collisions are free because we have cycles to burn. :)
The quantum ownership case is "so long as I have work to do, if the scheduler gave me a quantum, it's my damn quantum!". In other words, the idea of voluntary preemption or semivoluntary preenption, such as one might get when the system makes a process blocke merely because it has made a system call that can't be immediately satisfied. A multithreaded of FSA process doesn't care about a single blocking context: it wants to use the remainder of its quantum.
I'm not sure I understand this nor how it applies.
-- -Alfred Perlstein - [bri...@wintelcom.net|alf...@freebsd.org] "I have the heart of a child; I keep it in a jar on my desk."
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