From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from outbound-smtp09.blacknight.com ([46.22.139.14]:51803 "EHLO outbound-smtp09.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753907AbdGJMhy (ORCPT ); Mon, 10 Jul 2017 08:37:54 -0400 Received: from mail.blacknight.com (pemlinmail05.blacknight.ie [81.17.254.26]) by outbound-smtp09.blacknight.com (Postfix) with ESMTPS id 25BA81C205C for ; Mon, 10 Jul 2017 13:37:53 +0100 (IST) From: Mel Gorman To: Linux-Stable Cc: Mel Gorman Subject: [PATCH 0/9] Performance-related backports for 4.12 Date: Mon, 10 Jul 2017 13:37:43 +0100 Message-Id: <20170710123752.7563-1-mgorman@techsingularity.net> Sender: stable-owner@vger.kernel.org List-ID: The 4.12 release was large but there was a number of important performance-related patches that are relatively low-hanging fruit. There are other patches but data is still being collected. This is a collection that have only been tested on 4.12 and while they may merge against older kernels, I have no data on how it behaves and cannot guarantee it's a good idea so I don't recommend it. Patch 1 is an x86 microoptimisation for processors with ERMS. The improvement is marginal with effects often within the noise but it's a small boost on syscall-intensive workloads that move a lot of data to userspace. Patches 2-3 reworks select_idle_cpu, particularly around idle scanning to use a limited scan instead of a complete cut-off. The boost for hackbench is variable with an old machine with limited CPUs only getting a 3-4% boost while a larger 2-socket machine with 48 cores saw a 7-20% boost for low thread counts and no difference when the machine was saturated. Other workloads that are not as wakeup intensive barely notice which is to be expected. Patch 4 addresses a soft lockup that was detected on a memory-intensive workload with large numbers of threads and NUMA balancing implemented. While I personally cannot verify the fix as the workload in question is not available, I know it was confirmed to work by a user. Patches 5-9 addresses a number of problems with automatic NUMA balancing. While the patch author said that there was a big boost on specjbb and NAS, this was on a 4-socket machine in a ring topology and I don't have access to a similar machine. However, on a 2-socket machine, there was a 5% boost to specjbb 2005 when running a single JVM and a 1-2% boost when using multiple JVMs. There was little or no difference to NAS on the same machine but this may be due to the fact it's a 2-socket machine and a relatively short-lived workload. It's also known to boost hackbench on some machines by roughly 20%. -- 2.13.1