On Tue, 2015-01-27 at 15:45 +0800, Huang Ying wrote: > Hi, Davidlohr, > > Any update on this? The latest news I gotten is that you finally > reproduced this.
The overall differences and cause of the issue is commit 37e9562453b (locking/rwsem: Allow conservative optimistic spinning when readers have lock). And since the performance issue occurs with writers-only, I'm fine with the degradation, we need to learn to live it. Real use cases will use mutexes instead. Also, the mentioned commit fixes a much more important problem than pathologically calling exec(2). Now, this doesn't mean we cannot do _anything_ about it. I sent a patcshet just a few days ago (sorry, I forgot to Cc you) that tries to minimalize (I've recovered ~75% of the regression) the writer penalties: https://lkml.org/lkml/2015/1/26/34 So all in all we don't really care for writer-only workloads, but hey, while we're at it. Thanks, Davidlohr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
