Date: Fri, 2 Nov 2007 17:51:26 -0700 (PDT) From: Nate Eldredge <nge@cs.hmc.edu> To: Marek Blaszkowski <mb@kis.p.lodz.pl> Cc: freebsd-amd64@freebsd.org Subject: Re: strange i/o and tty lockups/delays on 6.1, strange sync() issue - updated - slow sata disk writes? Message-ID: <Pine.LNX.4.64.0711021737250.31199@knuth.cs.hmc.edu> In-Reply-To: <472B5111.8010109@kis.p.lodz.pl> References: <4728906E.8020804@kis.p.lodz.pl> <Pine.LNX.4.64.0710311048450.31199@knuth.cs.hmc.edu> <472B2FBB.5070308@kis.p.lodz.pl> <472B5111.8010109@kis.p.lodz.pl>
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On Fri, 2 Nov 2007, Marek Blaszkowski wrote:
> Hi, I done more tests, it's looks like for unknown reason bootleneck is
> (maybe) sata controller (?).
Are you sure it's only disk access that causes the stall? I ran a test
program like the following; it reports whenever it's scheduled out for
more than argv[1] microseconds. You could also try running it in single
user mode for a minimum of disk activity. If you want to get really
involved you could boot from a ramdisk or something.
Btw, regarding PREEMPTION: I don't know if it is "officially" safe or not.
I haven't had any problems using it on my box, but it's not particularly
heavily loaded either.
Have you tried disabling ACPI yet?
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
int main(int argc, char *argv[])
{
long t;
struct timeval old,new;
if (argv[1])
t = atol(argv[1]);
else
t = 0;
gettimeofday(&old,NULL);
while (1)
{
long diff;
gettimeofday(&new, NULL);
diff = (new.tv_sec - old.tv_sec) * 1000000 + (new.tv_usec -
old.tv_usec);
if (diff >= t)
printf("%ld\n",diff);
old = new;
}
return 0;
}
--
Nate Eldredge
nge@cs.hmc.edu
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