You can possibly run 'top' command parallely in another session to see if the processor or memory is hitting the ceiling during this time. That should give a clue hopefully. Srini On 3/8/07, Elliot Lee <sopwith@xxxxxxxxx> wrote:
Sorry, I really should have given details on my system, especially the kernel version: Linux 2.6.19-1.2911.fc6 #1 SMP x86_64 Pentium 4 3.00 GHz CPU, 1G RAM ext3 on LVM on RAID-5 on 5 * 500G SATA drives. Best, -- Elliot On Mar 7, 2007, at 19:36 , Elliot Lee wrote: > Hi all, > > I've got a 1.8TB LVM-on-RAID filesystem that was performing OK but > really didn't seem like it was going as fast as it should. I ran > the commands below and got some pretty startling results... > > A 60% performance hit for a linear mapping is heinous. What can I > do to help get this fixed? > > Best, > -- Elliot > > # dmsetup create foo --table '0 3880910848 linear 9:0 0' > > # dd if=/dev/md0 of=/dev/null bs=1048576 count=4096 > 4096+0 records in > 4096+0 records out > 4294967296 bytes (4.3 GB) copied, 20.2362 seconds, 212 MB/s > > # dd if=/dev/mapper/foo of=/dev/null bs=1048576 count=4096 > 4096+0 records in > 4096+0 records out > 4294967296 bytes (4.3 GB) copied, 55.3597 seconds, 77.6 MB/s > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
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