On Mon, May 18 2009 at 1:57pm -0400, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote: > On Fri, May 15 2009, Martin K. Petersen wrote: > > From: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > > > > To support devices with physical block sizes bigger than 512 bytes we > > need to ensure proper alignment. This patch adds support for exposing > > I/O topology characteristics as devices are stacked. > > > > logical_block_size is the smallest unit the device can address. > > > > physical_block_size indicates the smallest I/O the device can write > > without incurring a read-modify-write penalty. > > > > The io_min parameter is the smallest preferred I/O size reported by > > the device. In many cases this is the same as the physical block > > size. However, the io_min parameter can be scaled up when stacking > > (RAID5 chunk size > physical block size). > > > > The io_opt characteristic indicates the optimal I/O size reported by > > the device. This is usually the stripe width for arrays. > > > > The io_alignment parameter indicates the number of bytes the start of > > the device/partition is offset from the device's natural alignment. > > Partition tools and MD/DM utilities can use this to pad their offsets > > so filesystem start on proper boundaries. > > > > Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > > --- > > Documentation/ABI/testing/sysfs-block | 59 +++++++++++ > > block/blk-settings.c | 184 +++++++++++++++++++++++++++++++++ > > block/blk-sysfs.c | 33 ++++++ > > block/genhd.c | 10 ++ > > fs/partitions/check.c | 10 ++ > > include/linux/blkdev.h | 47 +++++++++ > > include/linux/genhd.h | 1 + > > 7 files changed, 344 insertions(+), 0 deletions(-) > > > > diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block > > index 44f52a4..93075cf 100644 > > --- a/Documentation/ABI/testing/sysfs-block > > +++ b/Documentation/ABI/testing/sysfs-block > > @@ -60,3 +60,62 @@ Description: > > Indicates whether the block layer should automatically > > generate checksums for write requests bound for > > devices that support receiving integrity metadata. > > + > > +What: /sys/block/<disk>/alignment > > +Date: April 2009 > > +Contact: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > > +Description: > > + Storage devices may report a physical block size that is > > + bigger than the logical block size (for instance a drive > > + with 4KB physical sectors exposing 512-byte logical > > + blocks to the operating system). This parameter > > + indicates how many bytes the beginning of the device is > > + offset from the disk's natural alignment. > > + > > +What: /sys/block/<disk>/<partition>/alignment > > +Date: April 2009 > > +Contact: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > > +Description: > > + Storage devices may report a physical block size that is > > + bigger than the logical block size (for instance a drive > > + with 4KB physical sectors exposing 512-byte logical > > + blocks to the operating system). This parameter > > + indicates how many bytes the beginning of the partition > > + is offset from the disk's natural alignment. > > I really hate the 'alignment' name, nobody will know wtf that is without > looking it up. The rest of the names are fairly self explanatory. > offset? offset_size? misalignment? Not very good with names, but perhaps > we can find something more appropriate :-) > > The rest of the patch set looks ok to me, if we can just agree on a > silly name, then lets merge it for 2.6.31. I agree that 'alignment' is too terse/confusing given that it is an offset we're exposing. How about 'alignment_offset'? Mike -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
