LSI 53c1030 (Fusion MPT) performance with O_SYNC

[Jan Oravec <jan.oravec@6com.sk>]

Hi,


I have got a new dual-Opteron server based on Tyan S2880 motherboard with
LSI53C1030 U320 controller onboard - there are 15kRPM Fujitsu disks.

I've noticed poor performance with MySQL/InnoDB when compared to another
S2880-based box with IDE disks.

I've tracked it to this:

Let's have this code (notice the O_SYNC) and enough large test file.

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

int main(int argc, void **argv)
{
  char buffer[64];
  int fd, i;

  fd=open(argv[1], O_WRONLY|O_SYNC);
  
  lseek(fd, 0, SEEK_SET);
  for(i=0; i<10000; i++)
    write(fd, buffer, 64);
  
  return 0;
}


The results are:

LSI53C1030:
$ time ./a.out testfile 

real    0m4.218s
user    0m0.002s
sys     0m0.219s


IDE:
$ time ./a.out testfile 

real    0m1.767s
user    0m0.002s
sys     0m0.356s


Changing size of written amount of data to 4096 the time ratio between
LSI53C1030 and IDE is around 1:1.


Both boxes are running vanilla 2.6.7 kernel.


Any help appreciated,


Jan


PS: please CC, I am not on the list.