From: dkf@chem.ucsd.edu (David Knight French) Subject: Re: NT vs Linux (was: Re: truth or dare) Date: 10 Jul 1993 09:30:37 GMT
In article <GTHAKER.93Jul9081940@trantor.atl.ge.com> gthaker@atl.ge.com (Gautam H. Thaker) writes:
>I too am really very happy with the speed of things like zcat |tar etc. on
>Linux. Is this all due to the buffer cache? I have been compiling same
>program both on Linux (8 Mb, 486/33 64k cache) and SUN SS2 (48 Mb, SUNOS
>4.1.3) with gcc 2.x.x. On Linux it compiles and links much much
>faster. Runs faster too, which I find even harder to believe. I hope to do
>some exact tests and post numbers. SS2 has no excuse for being slower.
>Perhaps SS2 is slower due to NFS, but with 48 Mb of memory not much else
>being done subsequent gcc calls ought to be fast, but are still rather slow.
Just to clairfy, I don't have Linux, yet! But I plan on getting it as soon
as I get my 486, but feel I may have something to add to this...
When I was taking my BSD Internals class, I asked the prof, Keith Muller--
a disk driver expert, for suggestions on how to track down some
performance problems we were having on our AIX machine. We basically had
a large number of disks on one SCSI controller and he suggested looking
into this...
To get to the short of it, he said one problem we would have with AIX
and disks was their concept of a memory mapped file system. No Buffer
Cache for the disk devices... He mentioned that SunOS added the same
thing with v4.1.2 (or maybe 4.1.3). According to him, based more on
SunOS than AIX, the file access would kill the SCSI bus. The problem
was in mapping all of the file BEFORE it could be accessed by the
program and kernel. The biggest problem was the mapping would
tie up the bus. The larger the file the bigger the problem.
His solution on the Sun was to fill up the sbus slots with extra SCSI
controllers and put one large disk on each one. At least this way
some disks were still accesable...
This MAY explain some of your perforance differences and then again
it MAY NOT...
Hope this is accurate... if not, I hope someone will set me straight.
It has been a while since that conversation...
>Gautam H. Thaker (gthaker@atl.ge.com) 609-866-6412 (fax x6397. Dialcom 8-777)
>Martin Adv. Tech. Lab., MS 145-2; Route 38; Moorestown, NJ 08057. 767-4396 (H)
-- David Knight French Email Addresses: Phone: UCSD - Dept of Chemistry INTERNET: dkfrench@ucsd.edu (voice/fax) 9500 Gilman Drive UUCP: ucsd!dkfrench (619)534-4193 / San Diego, CA 92093-0314 BITNET: dkfrench@ucsd.bitnet (619)534-6255