Hello!
Could somebody please explain the following bad performance of a machine
running ZFS. I have a feeling it has something to with the way ZFS uses
memory, because I've checked with ::kmastat and it shows that ZFS uses
huge amounts of memory which I think is killing the performance of the
machine.
This is the test program:
#include <malloc.h>
#include <stdio.h>
int main()
{
char *buf = calloc(512000000,1);
if ( buf == NULL ) {
printf("Allocation failed.\n");
}
return 0;
}
I've run the test program on the following two different machines, both
under light load:
Machine A is AMD64 3000+ (2.0GHz), 1GB RAM running snv_46.
-----
Machine B is Pentium4, 2.4GHz, 512MB RAM running Linux.
Execution times on several consecutive runs are:
Machine A
------------
time ./a.out
./a.out 0.49s user 1.39s system 2% cpu 1:03.25 total
./a.out 0.48s user 1.28s system 3% cpu 50.691 total
./a.out 0.48s user 1.27s system 4% cpu 38.225 total
./a.out 0.48s user 1.24s system 5% cpu 30.694 total
./a.out 0.47s user 1.20s system 5% cpu 28.640 total
./a.out 0.47s user 1.23s system 6% cpu 28.210 total
./a.out 0.47s user 1.21s system 6% cpu 27.700 total
./a.out 0.47s user 1.19s system 9% cpu 17.875 total
./a.out 0.46s user 1.15s system 12% cpu 12.784 total
On machine B
------------
[the first run took approx. 10 seconds, I forgot to paste it]
./a.out 0.14s user 0.89s system 27% cpu 3.711 total
./a.out 0.13s user 0.87s system 25% cpu 3.926 total
./a.out 0.11s user 0.90s system 29% cpu 3.456 total
./a.out 0.11s user 0.91s system 29% cpu 3.435 total
./a.out 0.10s user 0.91s system 38% cpu 2.597 total
./a.out 0.11s user 0.93s system 35% cpu 2.913 total
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