Author: Dieter Buerssner
Date: 14:23:48 05/06/04
Go up one level in this thread
On May 05, 2004 at 11:53:33, Robert Hyatt wrote:
>Question is, how much time? The directory contents will be cached. No I/O at
>all will be done. It probably won't take a second although you could test that
>with a dinky program that tries to open 33K bogus filenames in the same
>directory...
>
>sample:
>
>#include <sys/types.h>
>#include <sys/stat.h>
>#include <fcntl.h>
>#include <string.h>
>main() {
> char fname[6];
> int fd;
> int i;
> for (i=0;i<33000;i++);
> sprintf(fname,"%d",i);
> fd = open(fname,O_RDONLY);
> if (fd > 0) {
> write(fd,fname,strlen(fname));
> close(fd);
> }
>}
>
>On my 2.8 xeon, here is how long it takes to run:
>
>
>
>crafty% time ./tstopen
>0.000u 0.000s 0:00.00 0.0% 0+0k 0+0io 75pf+0w
Out of curiosity, I tried your example on Win XP with MSVC 6 and with Gcc 3.2.
Took also practically zero time. BTW. Why do yo try to write to fd, that is
opened read only?
I tried a similar example, using Standard C functions (as does the Nalimov
code):
#include <stdio.h>
int main(void)
{
FILE *fp;
int i;
char fname[16];
for (i=0; i<33000; i++)
{
sprintf(fname, "%d", i);
fp = fopen(fname, "rb");
if (fp)
fclose(fp);
}
return 0;
}
G:\src\yace>ptime h2
Time of Execution: 00:00:07.75
13 seconds with the Gcc compile.
I also tried the time used to initialize the TBs on my computer. I have all
3/4/5 men TBs and knnknn as the only 6-men TB (it is the smallest to download).
I used the TB code from Crafty 19.12 egtb.cpp (almost) unmodified.
Initializing TBs took 12 seconds. Setting the path for tbs to c:\notexist and
initializing TBs (none were found, of course) took 6 seconds. setting it to
"nul" (which should correspond to /dev/null in the Unix world): 5 s.
Last I set tbldir \ne1; \ne2; \ne3; \ne4; \ne5 -> 23 s (obviously no HD accesses
during this, HD light was dark). I repeated this with Virus scanner disabled -
same result.
No, it really does not bother me - but typically people will see much larger
times than you see. My computer is not that slow - P4 2.53 GHz. The disk is very
new, and I think rather fast for an IDE disk.
Regards,
Dieter
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.