Bug 142007 – DVD-RAm Cache problem

• Status: RESOLVED UPSTREAM
• Product: Gentoo Linux

[Description Frank Noack 2006-07-28 06:57:14 UTC]

The writing of dvd-ram with udf is very buggy. If i mount a udf formated dvd-ram with a udev hal based gentoo system it (auto) gets the following mount options.
# mount
/dev/hde on /media/cdrecorder type udf (rw,nosuid,nodev,user=frank)

with this options i cant write normal on dvd-ram. I get an higher and higher cpu load up to 8 and an unusable system. Only if i mount with "-o sync,dirsync" i can write to dvd-ram with an reasonable cpu-load.

see here please: http://forums.gentoo.org/viewtopic-t-481464-highlight-.html

It shows like a problem with cache management of recent kernels.
see here please: http://bugzilla.kernel.org/show_bug.cgi?id=5893

mine idea for a first workaround would be to say hal to mount dvd-ram with -o sync,dirsync

[Comment 1 Daniel Drake (RETIRED) 2006-08-13 02:42:35 UTC]

Please reproduce this on the latest development kernel, currently 2.6.18-rc4

[Comment 2 Frank Noack 2006-08-13 07:50:43 UTC]

(In reply to comment #1)
> Please reproduce this on the latest development kernel, currently 2.6.18-rc4
> 
I tested with 2.6.18-rc4. top says:
top - 16:02:38 up 57 min,  1 user,  load average: 5.51, 5.94, 4.83
Tasks: 104 total,   7 running,  97 sleeping,   0 stopped,   0 zombie
Cpu(s):  8.6% us,  2.3% sy,  2.0% ni,  0.0% id, 86.0% wa,  0.7% hi,  0.3% si
Mem:    515100k total,   509560k used,     5540k free,     9984k buffers
Swap:   987956k total,    97888k used,   890068k free,   177040k cached

for 313 MB i need over 22 minutes for copy. past 28 minutes the cache is written on disk. 

It looks like before. High CPU load, slow speed 200 KB/s for big files. 

[Comment 3 Daniel Drake (RETIRED) 2006-08-13 08:05:53 UTC]

Thanks, will watch upstream bug

[Comment 4 Frank Noack 2006-08-15 10:28:05 UTC]

(In reply to comment #3)
> Thanks, will watch upstream bug
> 

I tested with kernel 2.6.17 and vm.dirty_ratio=0 (standart vm.dirty_ratio=40) i got a better performanc with lower cpu-load.
#mount
/dev/hde on /media/cdrecorder type udf (rw,noatime)
I copied 698 Mb 
real    14m40.762s
user    0m0.098s
sys     0m6.399s

------------------------------------------------------------------
The same copy with vm.dirty_ratio=40

real    25m55.849s
user    0m0.086s
sys     0m6.638s

hth Frank

[Comment 5 Daniel Drake (RETIRED) 2006-08-15 11:06:56 UTC]

Please write that (and all other info you find) on the upstream bug