Date: Mon, 4 May 1998 17:10:54 +0930 From: Greg Lehey <grog@lemis.com> To: Joerg Micheel <joerg@krdl.org.sg> Cc: John-Mark Gurney <gurney_j@resnet.uoregon.edu>, FreeBSD Hackers <hackers@FreeBSD.ORG> Subject: Re: Context switch time Message-ID: <19980504171054.X4777@freebie.lemis.com> In-Reply-To: <19980504152056.47011@krdl.org.sg>; from Joerg Micheel on Mon, May 04, 1998 at 03:20:56PM %2B0800 References: <Pine.BSF.3.96.980425041329.28708A-100000@fledge.watson.org> <19980425034313.55993@hydrogen.nike.efn.org> <19980504143736.L4777@freebie.lemis.com> <19980503222303.36966@hydrogen.nike.efn.org> <19980504140442.52763@krdl.org.sg> <19980504155242.P4777@freebie.lemis.com> <19980504152056.47011@krdl.org.sg>
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On Mon, 4 May 1998 at 15:20:56 +0800, Joerg Micheel wrote:
> Greg,
>
> maybe, we should exchange our test programs :-).
#include <stdio.h>
#include <sys/fcntl.h>
main (int argc, char *argv [])
{
int i;
int count = 1;
if (argc > 1)
count = atoi (argv [1]);
for (i = 0; i < count; i++)
getuid ();
}
Hmm, interesting, it's called getpid.c, but it calls getuid :-)
> On Mon, May 04, 1998 at 03:52:42PM +0930, Greg Lehey wrote:
>> On Mon, 4 May 1998 at 14:04:42 +0800, Joerg Micheel wrote:
>>> On Sun, May 03, 1998 at 10:23:03PM -0700, John-Mark Gurney wrote:
>>>> Greg Lehey scribbled this message on May 4:
>>>>> On Sat, 25 April 1998 at 3:43:13 -0700, John-Mark Gurney wrote:
>>>>>
>>>>> Strange. This is what I get from a program that repeatedly calls
>>>>> getpid() on my K6/233:
>>>
>>> These numbers might not that much depend on processor type/speed. What
>>> about memory/cache speed ? Chipset ? Comments ?
>>
>> I think they have quite a strong relationship with processor power.
>
>> In particular, the P5/133 and your P5/200 seem to handle about 3500
>> syscalls/MHz. The P5/75 is presumably slower because of the missing
>> cache, and I've noticed before that the K6 isn't as much faster at
>> this sort of thing as I would expect--suggestions for the reasons are
>> welcome. One could be that it's an Inten TX board with 96 MB, of
>> which only 64 MB are cached, but it seems to match up with John-Mark's
>> observations.
>
> Here is the Dell OptiPlex GXa, a 300 MHz PentiumPro:
>
> (results omitted)
> 1375755 usecs/1000000 calls, 726873 calls/sec
>
> You seem to be right in some way, but the result does not directly suggest that
> there is a 1:1 relationship with processor speed, at least not on the high-end machines.
> The performance gain on the 300 MHz machine is VERY slight (around 1%).
>
> Unfortunately, I currently don't have any slower machines around. I might
> try on my 133MHz Pentium at home tonight.
Hmmm. This suggests to me that we're hitting some other limit.
Greg
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