Nate Diller wrote:
> i really recommend you focus on getting better disk bandwidth, you stand
> to gain a lot more from that approach. i presume you're on ext3;
> perhaps you should try reiser4 or xfs, they are more likely to meet your
> disk bandwidth requirements.
>
> NATE
While I have already solved the issue that was troubling me, I also spent some time comparing different
filesystems as reccommended by Nate, with interesting results.
My method was simple - make a filesystem and the set it as the target for my video capture. With video
coming in at 25MBytes/sec and going out to disk at about 15-20MBytes/sec it is an interesting test of the
vm and filesystem.
I compared ext2,ext3,xfs,vfat,reiser and reiser4.
The hands-down winner was ext2. All the others showed problems of either lower disk throughput
or dropped frames during video capture.
Only ext2 went the full distance - no dropped frames until we run out of RAM, and good disk throughput.
xfs,reiser and reiser4 had slightly higher disk write speed, but showed performance problems
that caused lots of dropped frames so they must be ruled out at this stage.
I know that xfs and reiser4 are supposed to be faster for some things, but it seems to me that they
are not the best choice when you are predominantly writing lots and lots of 600k files :-)
regards, Anthony
--
Anthony Wesley
Director and IT/Network Consultant
Smart Networks Pty Ltd
Acquerra Pty Ltd
[email protected]
Phone: (02) 62595404 or 0419409836
Anthony Wesley <[email protected]> wrote:
>
> I compared ext2,ext3,xfs,vfat,reiser and reiser4.
>
> The hands-down winner was ext2. All the others showed problems of either lower disk throughput
> or dropped frames during video capture.
ext2 is a good filesystem. For that sort of application all the journaling
gunk can really get in the way.
You should have tested ext3 with data=writeback.
Andrew Morton wrote:
> Anthony Wesley <[email protected]> wrote:
>
>>I compared ext2,ext3,xfs,vfat,reiser and reiser4.
>>
>> The hands-down winner was ext2. All the others showed problems of either lower disk throughput
>> or dropped frames during video capture.
>
>
> ext2 is a good filesystem. For that sort of application all the journaling
> gunk can really get in the way.
>
> You should have tested ext3 with data=writeback.
>
Ask and ye shall receive...
I created an ext3 fs, mounted it with data=writeback and gave it a quick spin.
The result? Lots of pauses and dropped frames during capture. This is during the part of the
process where I have gobs of free RAM that's being used for buffering so dropping frames here
is a cardinal sin.
Dunno why it's happening, but I saw it also with xfs and reiser4. ext2 on the other hand
chugs along happily, no pauses, no dropped frames until we run out of free RAM (takes about 2
minutes now after the simple kernel change).
I can understand dropped frames after we run out of ram, but not before.
regards, Anthony
--
Anthony Wesley
Director and IT/Network Consultant
Smart Networks Pty Ltd
Acquerra Pty Ltd
[email protected]
Phone: (02) 62595404 or 0419409836