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slow CD ripping from moving from 2.4.4 to 2.4.17

DISCUSSION Karol Pietrzak 1 participant 1 message Jan 5, 2002

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Karol Pietrzak

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Hello.
I am the original poster, and I am happy to say that my problem has been solved thanks to Mark Hahn. The solution was to tweak the VM (via /proc/sys/vm/bdflush).

Here's the excerpt from fs/buffer.c which I looked at:

union bdflush_param {
	struct {
		int nfract;	/* Percentage of buffer cache dirty to 
				   activate bdflush */
		int dummy1;	/* old "ndirty" */
		int dummy2;	/* old "nrefill" */
		int dummy3;	/* unused */
		int interval;	/* jiffies delay between kupdate flushes */
		int age_buffer;	/* Time for normal buffer to age before we 
flush it */
		int nfract_sync;/* Percentage of buffer cache dirty to 
				   activate bdflush synchronously */
		int dummy4;	/* unused */
		int dummy5;	/* unused */
	} b_un;
	unsigned int data[N_PARAM];
} bdf_prm = {{40, 0, 0, 0, 5*HZ, 30*HZ, 60, 0, 0}};

After a little tinkering, this is now in my /etc/init.d./boot.local :
echo "10 0 0 0 500 3000 5 0 0" > /proc/sys/vm/bdflush

Thus, the only modified numbers are:
1. nfract : from 40% to 10% (Percentage of buffer cache dirty to

activate bdflush)
2. nfract_sync : from 60% to 5% (Percentage of buffer cache dirty to activate bdflush synchronously)

I don't quite understand what all that means (my knowledge of C is very limited), but it works :)

Once again, thank you. You've made me a happy Linux user... Ripping performance, with these changes in place, is now around 26-30X, where before, it was 13-15X.

Quoted 43 lines · On 31 Dec 2001, [email protected] wrote:

Hello.
Using 2.4.4 up to, I believe, 2.4.14, CD ripping was fine. My Plextor 12/10/32S (S for SCSI) ripped audio CDs at around 25X, even sometimes at 30X. While ripping, my hard drive would work continuously, and so would my CDRW drive.

Now with 2.4.17, my hard drive can't keep up with my CDRW drive:
everything happens in bursts. My CDRW drive starts ripping as fast as possible, but my hard drive doesn't do anything (0-5 seconds). Then, my hard drive decides to start writing, which stops the CD ripping process (5-8 seconds). Now that the hard drive is done, the CDRW drive continues ripping... for 4 seconds and the process continues over and over again. This brings down the ripping speed down to ~18X, a far cry from the 30X achieved with 2.4.4 and very close to the writing speed of my CDRW drive (12X), which is ridiculous.

As stated before, ripping is fine in 2.4.4 (which I still keep around because of this problem). What does help in 2.4.17, however, is manually entering running the 'sync' command ever second or so on another console. This makes the ripping process a lot more "continuous," like 2.4.4.

I can't burn CDs in 2.4.4, however, because that freezes up my computer, for some reason. That happens a lot less often in 2.4.17 (but that's another matter).

I am using SuSE 7.2 Pro with the latest cdda2wav (1.11a12).

Linux linux 2.4.17 #2 Fri Dec 21 17:14:19 EST 2001 i586 unknown

Gnu C                  2.95.3
Gnu make               3.79.1
binutils               2.10.91.0.4
util-linux             2.11b
mount                  2.11b
modutils               2.4.5
e2fsprogs              1.19
reiserfsprogs          3.x.0k-pre15
PPP                    2.4.0
Linux C Library        x    1 root     root      1343073 May 11 
2001 /lib/libc.so.6 Dynamic linker (ldd)   2.2.2 Procps          
      2.0.7 Net-tools              1.60 Kbd
Quoted 7 lines

1.04 Sh-utils 2.0 Modules Loaded ppp_async
ppp_generic slhc nls_cp437 vfat fat

I am using a Pentium I 233 with 32MB of RAM. I have an Advansys Ultra SCSI card with 3 devices total hooked up to it.

Anyone have any ideas? Anything I can do?

--
Karol Pietrzak
PGP KeyID: 3A1446A0