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: | Terry Lambert (tlam...@mindspring.com) | |
| Date: | Oct 7, 2002 5:47:40 pm | |
| List: | org.freebsd.freebsd-arch | |
Luigi Rizzo wrote:
i wonder what do we gain by moving to 32 bit m_tag_id -- because there is is still no strict guarantee that we have no conflicts if people randomly choose "cookies", and also, using the same reasoning for allocations one could argue that having the cookie chosen as the number of _days_ since the epoch, will still give low conflict probability while still fitting in 16 bits.
Julian wants to use "32 bit seconds since epoch" as the "random" value, and then rely on statistical protection. This wasn't clear to me, either. It depends on knowing netgraph developement well enough, and following the recommended approach well enough that you use the seconds-since-epoch method of obtaining interface IDs.
Also, those modules that require one or a very small number of different annotations (e.g. all the ones currently using m_tags) would just need the "cookie", whereas others with a large set of subfields could as well consider the field_id as part of the opaque data.
That's why I suggested a void *, and that it would not be good enough for 64 bit machines.
If everyone followed the seconds-since-epoch assignment methodology, though, Julian's approach would provide statistical protection (I worry about "the birthday paradox" making the likelihood much higher; for example, I'd expect the space to be smaller almost instantly, due to time zones...).
-- Terry
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