On Tue, Jan 15, 2008 at 07:44:15PM -0800, Andrew Morton wrote: > On Wed, 16 Jan 2008 11:01:08 +0800 Fengguang Wu <[EMAIL PROTECTED]> wrote: > > > On Tue, Jan 15, 2008 at 09:53:42AM -0800, Michael Rubin wrote: > > > On Jan 15, 2008 12:46 AM, Peter Zijlstra <[EMAIL PROTECTED]> wrote: > > > > Just a quick question, how does this interact/depend-uppon etc.. with > > > > Fengguangs patches I still have in my mailbox? (Those from Dec 28th) > > > > > > They don't. They apply to a 2.6.24rc7 tree. This is a candidte for 2.6.25. > > > > > > This work was done before Fengguang's patches. I am trying to test > > > Fengguang's for comparison but am having problems with getting mm1 to > > > boot on my systems. > > > > Yeah, they are independent ones. The initial motivation is to fix the > > bug "sluggish writeback on small+large files". Michael introduced > > a new rbtree, and me introduced a new list(s_more_io_wait). > > > > Basically I think rbtree is an overkill to do time based ordering. > > Sorry, Michael. But s_dirty would be enough for that. Plus, s_more_io > > provides fair queuing between small/large files, and s_more_io_wait > > provides waiting mechanism for blocked inodes. > > > > The time ordered rbtree may delay io for a blocked inode simply by > > modifying its dirtied_when and reinsert it. But it would no longer be > > that easy if it is to be ordered by location. > > What does the term "ordered by location" mean? Attemting to sort inodes by > physical disk address? By using their i_ino as a key? > > That sounds optimistic.
Yes, exactly. Think about email servers with lots of dirty files. > > If we are going to do location based ordering in the future, the lists > > will continue to be useful. It would simply be a matter of switching > > from the s_dirty(order by time) to some rbtree or radix tree(order by > > location). > > > > We can even provide both ordering at the same time to different > > fs/inodes which is configurable by the user. Because the s_dirty > > and/or rbtree would provide _only_ ordering(not faireness or waiting) > > and hence is interchangeable. > > > > This patchset could be a good reference. It does location based > > ordering with radix tree: > > > > [RFC][PATCH] clustered writeback <http://lkml.org/lkml/2007/8/27/45> > > list_heads are just the wrong data structure for this function. Especially > list_heads which are protected by a non-sleeping lock. list_heads are OK if we use them for one and only function. We have been trying to jam too much into s_dirty in the past. Grabbing a refcount could be better than locking - anyway if we split the functions today, it would be easy to replace the list_heads one by one in the future. -- 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/