Re: [PATCH] Invalidate_inodes can be very slow

[William Lee Irwin III <wli@holomorphy.com>]

William Lee Irwin III <wli@holomorphy.com> wrote:
>> Untested brute-force forward port to 2.6.0-test7-bk4. No idea if the
>>  locking is correct or if list movement is done in all needed places.

On Mon, Oct 13, 2003 at 04:08:21AM -0700, Andrew Morton wrote:
> My preferred approach to this would be to move all the global inode lists
> into the superblock so both they and inode_lock become per-sb.
> It is a big change though.  And, amazingly, nobody has yet hit sufficient
> inode_lock contention to warrant it.
> Yes, I bet that this search will hurt like hell on a really big box which
> has thousands of auto-expiring NFS mounts.  Please test your patch and I'll
> queue it up while we think about it some more.

Generally dcache_lock stands in front of inode_lock, even with the
current hashtable RCU code. inode_lock has been seen before in unusual
situations I don't remember offhand, though generally it's not #1.
The workloads used for, say, benchmark testing don't adequately model
situations like what you just mentioned (or a number of other real-life
usage cases), so per-sb inode_lock may be worth considering on a priori
grounds, though it would probably be better to actually set something
up to test that scenario.

-- wli