Hello,

On Mon, Sep 24, 2012 at 12:25:00PM +0400, Glauber Costa wrote:

quoted

This is kinda nasty.  Do we really need to do this?  How long would a
dead cache stick around?

Without targeted shrinking, until all objects are manually freed, which
may need to wait global reclaim to kick in.

In general, if we agree with duplicating the caches, the problem that
they may stick around for some time will not be avoidable. If you have
any suggestions about alternative ways for it, I'm all ears.

I don't have much problem with caches sticking around waiting to be
reaped.  I'm just wondering whether renaming trick is really
necessary.

quoted

Reaping dead caches doesn't exactly sound like a high priority thing
and adding a branch to hot path for that might not be the best way to
do it.  Why not schedule an extremely lazy deferrable delayed_work
which polls for emptiness, say, every miniute or whatever?

Because this branch is marked as unlikely, I would expect it not to be a
big problem. It will be not taken most of the time, and becomes a very
cheap branch. I considered this to be simpler than a deferred work
mechanism.

If even then, you guys believe this is still too high, I can resort to that.

It's still an otherwise unnecessary branch on a very hot path.  If you
can remove it, there's no reason not to.

Thanks.

-- 
tejun