According to Andrew Morton: > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.3-rc2/2.6.3-rc2-mm1/ > +dm-01-export-dm_vcalloc.patch > +dm-02-move-to_bytes-to_sectors.patch > +dm-03-remove-dm_deferred_io.patch > +dm-04-maintain-bio-ordering.patch > +dm-05-alloc_dev-error-cleanup.patch > +dm-07-dm_table_create-GFP-fix.patch > +dm-08-zero-size-target-fix.patch > +dm-09-dec_pending-locking-cleanup.patch > +dm-10-drop-BIO_SEG_VALID.patch The maintain-bio-ordering patch mostly fixes the performance problem I was seeing on XFS-over-LVM-on-3ware-raid5. (See my earlier message at http://www.ussg.iu.edu/hypermail/linux/kernel/0312.3/0684.html ) Excellent! However there's still one issue: I created a LVM volume on /dev/sda2, called /dev/vg0/test. Then I created and mounted an XFS partition on /dev/vg0/test. XFS uses a 512 byte blocksize by default, but the underlying /dev/sda2 device had a soft blocksize of 4096 (default after boot is 1024, but I had been mucking around with it so it got set to 4096). As a result, I couldn't get more than 35 MB/sec write speed out of XFS mounted on the LVM device. I added this little patch: --- drivers/md/dm-table.c.ORIG 2004-02-12 20:49:47.000000000 +0100 +++ drivers/md/dm-table.c 2004-02-12 20:56:59.000000000 +0100 @@ -361,7 +361,7 @@ blkdev_put(bdev, BDEV_RAW); else { d->bdev = bdev; - set_blocksize(bdev, d->bdev->bd_block_size); + set_blocksize(bdev, 512); } return r; } This forces the underlying device(s) to a soft blocksize of 512. And I had my 80 MB/sec write speed back ! I'm not sure if setting the blocksize of the underlying device always to 512 is the right solution. I think that set_blocksize for dm devices should also set the size for the underlying devices, but that probably means adding an extra hook so that set_blocksize can call bdev->bd_disk->fops->set_blocksize(bdev, size). Which, in the case of dm, would basically call set_blocksize for the underlying devices again. Correct ? Mike. _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
