Is it worth the effort for 32 bit when most production servers are 64? Or am I missing the point?
Gavin. On 10/19/08, Howard Chu <[EMAIL PROTECTED]> wrote: > Seems like I keep poking at this idea again every couple years. > > If we use a <base,vector> we can cover a much wider range without losing any > precision. For a 32 bit machine, 32 bits per word would cover 5 bits worth > of > entry IDs. So 27 bits would comprise the base, and the next 32 bits would > represent up to 32 entry IDs. > > To avoid wasting those 5 unneeded bits in the base, we could use them as a > run-length counter and use multiple vectors per base. But it might be better > to slide things over and use just a 24 bit base, and use the bottom 8 bits > of > the word as a bitmask to represent which following vectors are present. E.g. > > ......01 means 1 vector follows, representing base+ 0-31. > ......02 means 1 vector follows, representing base+32-63. > ......05 means 2 vectors follow, base+0-31 then base+64-95. > > That allows us to represent up to 256 entryIDs in only 288 bits (instead of > the 16384 bits we currently need). That would allow us to track about 1.86M > entryIDs in the same space we currently use to track only 64K entryIDs. > > It seems we would still need some kind of range representation to handle > IDLs > with more than 1.86M entries. > > -- > -- Howard Chu > CTO, Symas Corp. http://www.symas.com > Director, Highland Sun http://highlandsun.com/hyc/ > Chief Architect, OpenLDAP http://www.openldap.org/project/ > -- Sent from my mobile device http://www.suretecsystems.com/services/openldap/
