40 messages in org.freebsd.freebsd-archRe: CFR: m_tag patch| From | Sent On | Attachments |
|---|---|---|
| Sam Leffler | Oct 6, 2002 9:38 pm | |
| Nate Lawson | Oct 6, 2002 10:01 pm | |
| Sam Leffler | Oct 6, 2002 10:21 pm | |
| Terry Lambert | Oct 6, 2002 11:09 pm | |
| Julian Elischer | Oct 6, 2002 11:32 pm | |
| Julian Elischer | Oct 7, 2002 12:29 am | |
| Sam Leffler | Oct 7, 2002 9:24 am | |
| Sam Leffler | Oct 7, 2002 9:31 am | |
| Sam Leffler | Oct 7, 2002 9:46 am | |
| Julian Elischer | Oct 7, 2002 2:20 pm | |
| Terry Lambert | Oct 7, 2002 3:34 pm | |
| Sam Leffler | Oct 7, 2002 3:52 pm | |
| Julian Elischer | Oct 7, 2002 4:10 pm | |
| Julian Elischer | Oct 7, 2002 4:22 pm | |
| Luigi Rizzo | Oct 7, 2002 4:30 pm | |
| Julian Elischer | Oct 7, 2002 4:55 pm | |
| Sam Leffler | Oct 7, 2002 5:06 pm | |
| Julian Elischer | Oct 7, 2002 5:10 pm | |
| Julian Elischer | Oct 7, 2002 5:14 pm | |
| Julian Elischer | Oct 7, 2002 5:23 pm | |
| Terry Lambert | Oct 7, 2002 5:31 pm | |
| Terry Lambert | Oct 7, 2002 5:47 pm | |
| Nate Lawson | Oct 7, 2002 10:42 pm | |
| Don Lewis | Oct 7, 2002 11:06 pm | |
| Julian Elischer | Oct 7, 2002 11:28 pm | |
| Julian Elischer | Oct 7, 2002 11:32 pm | |
| Terry Lambert | Oct 8, 2002 12:42 am | |
| Terry Lambert | Oct 8, 2002 12:53 am | |
| Harti Brandt | Oct 8, 2002 1:19 am | |
| Nate Lawson | Oct 8, 2002 11:25 am | |
| Don Lewis | Oct 8, 2002 12:15 pm | |
| Sam Leffler | Oct 8, 2002 6:25 pm | |
| JINMEI Tatuya / 神明達哉 | Oct 10, 2002 7:33 pm | |
| Sam Leffler | Oct 11, 2002 11:11 am | |
| JINMEI Tatuya / 神明達哉 | Oct 16, 2002 3:03 am | |
| Luigi Rizzo | Oct 16, 2002 7:45 am | |
| JINMEI Tatuya / 神明達哉 | Oct 16, 2002 11:06 am | |
| Luigi Rizzo | Oct 16, 2002 11:18 am | |
| Julian Elischer | Oct 16, 2002 11:24 am | |
| Sam Leffler | Oct 16, 2002 11:29 am |
| Subject: | Re: CFR: m_tag patch | |
|---|---|---|
| From: | Don Lewis (dl-f...@catspoiler.org) | |
| Date: | Oct 7, 2002 11:06:02 pm | |
| List: | org.freebsd.freebsd-arch | |
On 7 Oct, Nate Lawson wrote:
On Mon, 7 Oct 2002, Julian Elischer wrote:
it is just working on the principal that there is not going to be a collision in the 32 bit space. Especially when we create them from "time since the epoch", and when teh various authors can see each other's choices of value.
There are deterministic ways to generate them. 1. A counter -- gettag() { return tag++; } 2. A LCRG -- gettag() { return (A * tag) % n; } 3. A global registry -- "Hey, gimme a major"
There are non-deterministic ways as well, i.e. hash functions and PRNGs. And if code can run faster than a given time source, the output of that source or permutation thereof can produce collisions.
What leads you towards the time-based option vs. the others, especially the deterministic ones?
Why not name them? At boot or module load time stuff the name in a table and use the table index as the 16 bit ID. Is there any reason the ID has to be the same each time the system is booted?
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