-----==
----== _
---== (_)__ __ ____ __ James Simmons
--== / / _ \/ // /\ \/ / jsimmons@edgeglobal.com
-=====/_/_//_/\_,_/ /_/\_\ fbcon/gfx developer
The choice of a GNU generation
On Tue, 30 Nov 1999, George wrote:
> On Mon, 29 Nov 1999, Benno Senoner wrote:
>
> >before claiming that this is a BIOS issue do the following:
> >
> >test this on a kernel with the low-latency patch applied with tuned EIDE
> >disks, AND running the mp3 player at higher priority (SCHED_FIFO
> >recommended) than the cat command.
>
> I don't have the low-latency patch currently but I do have this on 2.2.13:
>
> IBM IDE 7200RPM 512kB cache hard drive (U)DMA with:
> /sbin/hdparm -c1 -d1 -u1 -X34 -W1 -k1 -K1 -S0 /dev/hd[ac]
>
> hdparm benches it at:
>
> /dev/hdc:
> Timing buffer-cache reads: 128 MB in 4.39 seconds =29.16 MB/sec
> Timing buffered disk reads: 64 MB in 6.25 seconds =10.24 MB/sec
>
> My test consisted of opening a 14 megabyte mailbox in Pine
> (/var/log/messages in my case, and it was cached).
>
> 11:56:41.122638 read(4, "Feb 17 00:02:03 moving syslogd 1"..., 14152466) = 14152466 <0.601153>
>
> There wasn't any screen activity at the time. It happened before the
> little spinning /-\| character.
>
> I was running it as:
>
> $ cat mail/foo > /dev/null;strace -tt -T -o x `which pine` -f foo -I q
>
> total used free shared buffers cached
> Mem: 128128 109796 18332 45072 2700 65456
> -/+ buffers/cache: 41640 86488
> Swap: 130532 23824 106708
>
> In fact, this cheesy little program causes IRQ timeouts as well:
>
> root@moving:~# cat read.c
> #include <fcntl.h>
>
> #define ALLOC 24*1024*1024
> int main(void)
> {
> char *buf = (char *)malloc(ALLOC);
> int fd;
>
> fd = open("/var/log/messages", O_RDONLY);
> read(fd, buf, ALLOC);
> close(fd);
> return 0;
> }
> root@moving:~# ls -l /var/log/messages
> -rw-r--r-- 1 root root 14242408 Nov 30 12:11 /var/log/messages
>
> Running this program 5 times in rapid succession just killed my
> SoundBlaster. Now I get an endless stream of "Sound: DMA (output) timed out
> - IRQ/DRQ config error?"
>
> Nov 30 12:10:31 moving kernel: Sound: DMA (output) timed out - IRQ/DRQ config error?
> Nov 30 12:11:02 moving last message repeated 61 times
> Nov 30 12:12:03 moving last message repeated 122 times
>
> Whee! Fortunately, a good kick in the pants (by rmmod/insmod) got the
> sound working again.
>
> -George Greer
>
>
>
> -
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