Re: [00/41] Large Blocksize Support V7 (adds memmap support)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Sep 18, 2007 at 11:00:40AM +0100, Mel Gorman wrote:
> We still lack data on what sort of workloads really benefit from large
> blocks (assuming there are any that cannot also be solved by improving
> order-0).

No we don't. All workloads benefit from larger block sizes when
you've got a btree tracking 20 million inodes and a create has to
search that tree for a free inode.  The tree gets much wider and
hence we take fewer disk seeks to traverse the tree. Same for large
directories, btree's tracking free space, etc - everything goes
faster with a larger filesystem block size because we spent less
time doing metadata I/O.

And the other advantage is that sequential I/O speeds also tend to
increase with larger block sizes. e.g. XFS on an Altix (16k pages)
using 16k block size is about 20-25% faster on writes than 4k block
size. See the graphs at the top of page 12:

http://oss.sgi.com/projects/xfs/papers/ols2006/ols-2006-paper.pdf

The benefits are really about scalability and with terabyte sized
disks on the market.....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group
-
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux