On Fri, Nov 21, 2014 at 02:19:27PM -0500, Jeff Layton wrote: > Here are the patches that I had mentioned earlier that reduce the > contention for the pool->sp_lock when the server is heavily loaded. > > The basic problem is that whenever a svc_xprt needs to be queued up for > servicing, we have to take the pool->sp_lock to try and find an idle > thread to service it. On a busy server, that lock becomes highly > contended and that limits the throughput. > > This patchset fixes this by changing how we search for an idle thread. > First, we convert svc_rqst and the sp_all_threads list to be > RCU-managed. Then we change the search for an idle thread to use the > sp_all_threads list, which now can be done under the rcu_read_lock. > When there is an available thread, queueing an xprt to it can now be > done without any spinlocking. > > With this, we see a pretty substantial increase in performance on a > larger-scale server that is heavily loaded. Chris has some preliminary > numbers, but they need to be cleaned up a bit before we can present > them. I'm hoping to have those by early next week. I have these merged on top of Trond's nfs-for-3.19-1 tag. The result is at git://linux-nfs.org/~bfields/linux-topics.git for-3.19-incoming if you want to check that I haven't screwed anything up. I'll probably push that to for-3.19 once it's passed a little more testing, and send a pull request once I've cleared my mailbox backlog and seen Trond's stuff merged. --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
