From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linutronix.de (146.0.238.70:993) by crypto-ml.lab.linutronix.de with IMAP4-SSL for ; 24 Jan 2019 09:55:16 -0000 Received: from [5.158.153.55] (helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1gmbj9-0001rp-Pt for speck@linutronix.de; Thu, 24 Jan 2019 10:55:15 +0100 Date: Thu, 24 Jan 2019 10:55:03 +0100 (CET) From: Thomas Gleixner Subject: Re: [PATCH v5 22/27] MDSv5 24 In-Reply-To: <20190123013923.GY6118@tassilo.jf.intel.com> Message-ID: References: <5fc3209d2880402d332ec93cf076467b3706a401.1547858934.git.ak@linux.intel.com> <20190122012233.GS6118@tassilo.jf.intel.com> <20190122175614.GV6118@tassilo.jf.intel.com> <20190123013923.GY6118@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit To: speck@linutronix.de List-ID: On Tue, 22 Jan 2019, speck for Andi Kleen wrote: > On Tue, Jan 22, 2019 at 07:56:20PM +0100, speck for Thomas Gleixner wrote: > > On Tue, 22 Jan 2019, speck for Andi Kleen wrote: > > > On Tue, Jan 22, 2019 at 05:09:05PM +0100, speck for Thomas Gleixner wrote: > > > At least in my limited testing the patch doesn't cause that > > > actually, even though it may be counterintuitive. > > > > > > See the numbers for Chrome for example in the last EBPF patch. That's > > > a complex workload with many context switches, and it gets > > > a clear roughly every third syscall > > > > I'd rather see numbers with the switch_to hackery actually using > > thread_info::flags. > > Not sure what you mean here? It's using thread_info flags. I told you before, but I'm happy to tell you once again: > + task_thread_info(next)->status |= > + task_thread_info(prev)->status & _TIF_CLEAR_CPU; > + task_thread_info(prev)->status &= ~_TIF_CLEAR_CPU; status != flags. IOW, the propagation logic is broken. Thanks, tglx