On Wed, 19 Sep 2012, Jeff Moyer wrote:
> Mikulas Patocka <[email protected]> writes: > > > On Wed, 19 Sep 2012, Jeff Moyer wrote: > > > >> Jeff Moyer <[email protected]> writes: > >> > >> > Hi, > >> > > >> > When testing against a pcie ssd or a ramdisk, making the block device > >> > structure cacheline_aligned provided a significant increase in > >> > performance: > >> > >> Self-NACK on this one. This results in a ton of warnings: > >> > >> include/linux/fs.h:727: warning: ???__section__??? attribute does not > >> apply to types > >> In file included from include/linux/debugfs.h:18, > >> from kernel/trace/trace_probe.h:28, > >> from kernel/trace/trace_kprobe.c:23: > >> include/linux/fs.h:727: warning: ???__section__??? attribute does not > >> apply to types > >> > >> And that leaves me with the task of figuring out if/why this actually > >> helps. > >> > >> Cheers, > >> Jeff > > > > Hi > > > > Use ____cacheline_aligned instead of __cacheline_aligned > > struct block_device is allocated as part of the bdev_inode: > > struct bdev_inode { > struct block_device bdev; > struct inode vfs_inode; > }; > > The bdev_inode is allocated from the bdev_cachep, which uses > SLAB_HWCACHE_ALIGN. So, in theory, this should already be aligned. > > -Jeff The purpose here is to align vfs_inode. If you add alignment to bdev, vfs_inode would be aligned (because bdev size would be aligned to cacheline boundary). Or you can add the alignment to vfs_inode, it would have the same effect. Mikulas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
