Re: Urgent: Manipulating large libraries
On Aug 19, Nikhil Nair wrote
> Has anyone experience with manipulating (ar, ranlib etc.) large libraries,
> of the order of tens of MB?
Only as part of package generation (and glibc is still nowhere near
> I need to order an Alpha this week. Budget restrictions mean I either get
> a 21164 366MHz / 1MB cache with 128MB SDRAM, or get a slightly faster
> machine with 64MB SDRAM.
My knee-jerk reaction would be to say get more RAM
> I've tried manipulating a large library (^17MB) on an old 60MHz
> Pentium, working on a SCSI-2 Jaz drive (so the disk is not too
> slow). A make, doing lots of ranlib's, takes nearly 30 minutes even
> if there are no changes; on an IBM rs/6000 43P (not a particularly
> fast workstation), it takes just a few seconds!
Well, a Jaz drive isn't all *that* speedy. Where/why are you using
ranlib at all? I am 100% certain GNU ar doesn't need it. Could it be
that ranlib on the rs/6000 is effectively a NOP?
> I'm rather worried. Swapping was not excessive - I have 24MB RAM,
> and at most 2MB of swap was in use. The disk was going most of the
> time, so I think ranlib on my PC was reading the huge lib in each
> time, whereas on the 43P (which has 192 MB), it was held in memory.
Yes, but during that operation, how much was buffered/cached according
to, say, top. I'd suspect not a lot.
> If this is the case, will I have a problem with only 64MB - there
> may be insufficient memory to buffer the whole lib (would it be
> buffered anyway)? A 17MB lib on an i586 would be larger on an
> Alpha, wouldn't it (I've heard that Alpha executables are larger)?
> Maybe I could put the lib in a large ramdisk ... but I'd need a lot
> of memory.
Yep, the lib will be bigger.
> I'd *really* appreciate any advice. I don't have much more than a
> day to make up my mind, so please hurry if you can.
I can summarize my thoughts:
1) Don't bother to use ranlib, with gnu ar you shouldn't need it.
2) The AIX ranlib may not have actually been doing anything.
3) If the AIX ranlib *was* doing something, it may have been caching
(which your machine probably doesn't have a whole lot of memory
for, with only 24MB)
4) Unless you're talking a dramatic difference in processor speed,
always get more memory.
The only way to make sure you're doing the right thing, though, would
be to do some concerted testing.
Don't touch that! It's the History Eraser Button
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