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
that size)
> 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.
Mike.
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