Messages in this thread | | | Date | Sun, 9 May 2004 01:43:00 +0530 | From | Dipankar Sarma <> | Subject | Re: dentry bloat. |
| |
On Sat, May 08, 2004 at 12:13:09PM -0700, Linus Torvalds wrote: > On Sat, 8 May 2004, Andrew Morton wrote: > > > > I think we can simply take ->d_lock a bit earlier in __d_lookup. That will > > serialise against d_move(), fixing the problem which you mention, and also > > makes d_movecount go away. > > If you do that, RCU basically loses most of it's meaning. > > You'll be taking a lock for - and dirtying in the cache - every single > dentry on the hash chain, which is pretty much guaranteed to be slower > than just taking the dcache_lock _once_, even if that one jumps across > CPU's a lot. > > In other words, no, I don't think that's a good idea. We really want to > take the dentry lock only after we're pretty sure we have the right > dentry. Otherwise the dentry chains will be bouncing from CPU to CPU all > the time.
Exactly. Taking ->d_lock for every dentry while traversing the hash chain should be avoided. As such, atomic operations on that path are getting costly.
Thanks Dipankar - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |