Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755088AbbDGPEI (ORCPT ); Tue, 7 Apr 2015 11:04:08 -0400 Received: from www.linutronix.de ([62.245.132.108]:38675 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753479AbbDGPEF (ORCPT ); Tue, 7 Apr 2015 11:04:05 -0400 From: Sebastian Andrzej Siewior To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Darren Hart , Steven Rostedt , fredrik.markstrom@windriver.com, Davidlohr Bueso , Manfred Spraul Subject: improve futex on -RT by avoiding the double wake-up Date: Tue, 7 Apr 2015 17:03:47 +0200 Message-Id: <1428419030-20030-1-git-send-email-bigeasy@linutronix.de> X-Mailer: git-send-email 2.1.4 X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 513 Lines: 11 On -RT we see a double wake up if the waiter has a higher priority than the process doing the wake up. Patch #1 avoids in the PI wake code, #2 in the non-PI variant (and only for one waiter). #3 is a small optimisation for message queues avoid a "cpu_relax()" loop. -- 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/