Anders Widman wrote: >>On Saturday, March 02, 2002 06:55:24 PM +0300 Oleg Drokin <[EMAIL PROTECTED]> wrote: >> > >>>Hello! >>> >>>On Fri, Mar 01, 2002 at 07:16:08PM +0100, Matthias Andree wrote: >>> >>>>I have some observation here that I cannot explain to myself. >>>>It seems as though ReiserFS impaired my throughput on 650 MB files, >>>>while ext3fs on the same drive did not. >>>> >>>Known problem. >>> >>>>drive to hold images for writing CDs, /dev/sdb4, formatted with >>>>reiserfs, and, because tail packing is pointless anyhow, mounted with -o >>>>notail. >>>> >>>Tails are not used for files bigger than 16k >>> >>>>However, when writing to an ATAPI 16x CD writer, the buffer ran empty, >>>>triggering burnproof support. I then ran zcav to figure how fast the >>>>drive itself was, and /dev/sdb ranged from 7.9 to 4.8 MB/s, no problem >>>>here. When I read a CD-Image with dd (tried default block size and >>>>bs=1048576), I only got 1.9 MB/s, evidently not sufficient to keep >>>>feeding the CD-writer (16x needs 2.4 MB/s). I then nuked the whole disk, >>>>reformatted it with ext3fs, everything is fine now, dd to the CD-Image >>>>gives me 7.8 MB/s with bs=1M. >>>> >>>>Does any of the *pending patches address this problem? I observed this >>>>on several kernel versions, 2.4.14, 2.4.16, 2.4.19-pre1-ac2. >>>> >>>This is a known problem. I and Chris are working on it exactly right now. >>>This is a problem related to the fact that metadata is located on the other >>>side of disk then the actual data. >>> > >>I would not say that speeds this bad are a known problem. 1.9MB/s is >>much too slow. Is that FS very full? Fragmentation is the only thing >>that should be causing this. >> > >>-chris >> > >Even with 'heavy' fragmentation this is quite low. A quick benchmark >of my 5400rpm 80GB disk gave me an average on 30MB/s. However, when >simulating large fragmentation (10 000+ fragments on a 1GB file) I get >about 2MB/s. > >Is DMA, unmask IRQ, read ahead and similar activated? > >//AW > > > So, if Anders nukes his ext3fs partition, and reformats with reiserfs, what is the performance?
We need the repacker. A pity it won't happen until January when v4.1 will come out. Hans
