Re: True fsync() in Linux (on IDE)

[Peter Zaitsev <peter@mysql.com>]

On Thu, 2004-03-18 at 12:11, Chris Mason wrote:

> > I believe some missed set_page_writeback() calls caused fsync() to never
> > really wait on anything, pretty broken... IIRC, it's fixed in latest
> > -mm, or maybe it's just pending for next release.
> 
> This should have only been broken in -mm.  Which kernels exactly are you
> comparing?  Maybe the 3ware array defaults to different writecache
> settings under 2.6?

I'm trying RH AS 3.0  kernel, however I have the same behavior on my 
SuSE 8.2 workstation. 

I use 2.6.3 kernel for tests now (It is not the latest I know) 
EXT3 file system.

3WARE has writeback cache setting in both cases. 


Here is the test program I was using: 


#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>


char buffer[4096] __attribute__((__aligned__(4096)));

main()
{
  int rc2,rc;
  int i;
  buffer[0]=(char)getpid();
  rc=open("write",O_RDWR | O_CREAT,0666);
  if (rc==-1) printf("Error at open: %d\n",errno);
  for(i=0;i<1000;i++)
   {
    rc2=write(rc,&buffer,4096);
    printf(".");
    fflush(stdout);
    if (rc2<0)
      {
        printf("Error code: %d\n",errno);
        return;
      }
  fsync(rc);
   }

}





-- 
Peter Zaitsev, Senior Support Engineer
MySQL AB, www.mysql.com

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