Kais Belgaied writes: > I am wondering what has been the experience of folks on this alias with > the performance gain or penalty > from the various choices above, or if they used different way for > efficiently and promptly reclaim.
I don't have the experience you're seeking, but a closely related issue is pinning down creds with dblks that chill out in TX descriptor blocks. A problem we've had with Zones is that the stream head puts on dblks with creds, those creds hold references to the zone_t, the zone_t in turn holds a reference to the root vnode_t for the zone, and thus you can't shut down or unmount a zone until the zone-related mblks floating around in the system somehow get cleaned up. If they're rotting away on a rarely-used (or perhaps even zone-specific) adapter, you may be in for a bad administrative hair day. We need to have those creds scrubbed away as soon as possible, either by semi-aggressively reclaiming TX resources or by having the creds stripped _before_ being placed on the TX queue. (Preferably by the Nemo framework.) However, one of the thorny problems I think this raises is that, at least for TCP, the db_ref counter is often greater than 1, so removing the credp may not be a kosher move. No, I don't know what the right fix is here, but this looks like a good place to throw the problem into the mix. ;-} For what it's worth, and at least a bit more related to the question you're asking, I'm fairly opposed to "tunables" for these sorts of fiddling internal design details. If we can't manage to get it right under all conditions, then we need to make it at least "self tuning" so that users don't have to tweak voodoo variables. No more "putq versus putnext" ndd flags, or their moral equivalent, please. -- James Carlson, Solaris Networking <james.d.carlson at sun.com> Sun Microsystems / 35 Network Drive 71.232W Vox +1 781 442 2084 MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677
