From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yh0-f54.google.com (mail-yh0-f54.google.com [209.85.213.54]) by kanga.kvack.org (Postfix) with ESMTP id BB4FB6B0031 for ; Mon, 16 Dec 2013 12:17:39 -0500 (EST) Received: by mail-yh0-f54.google.com with SMTP id z12so3975331yhz.13 for ; Mon, 16 Dec 2013 09:17:39 -0800 (PST) Received: from mail-vc0-x232.google.com (mail-vc0-x232.google.com [2607:f8b0:400c:c03::232]) by mx.google.com with ESMTPS id gu7si8460545qab.137.2013.12.16.09.17.36 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 16 Dec 2013 09:17:37 -0800 (PST) Received: by mail-vc0-f178.google.com with SMTP id lh4so3367416vcb.37 for ; Mon, 16 Dec 2013 09:17:35 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20131216103944.GO11295@suse.de> References: <1386964870-6690-1-git-send-email-mgorman@suse.de> <52AB8C68.1040305@zytor.com> <20131216103944.GO11295@suse.de> Date: Mon, 16 Dec 2013 09:17:35 -0800 Message-ID: Subject: Re: [PATCH 0/4] Fix ebizzy performance regression due to X86 TLB range flush v2 From: Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: "H. Peter Anvin" , Alex Shi , Ingo Molnar , Thomas Gleixner , Andrew Morton , Fengguang Wu , Linux-X86 , Linux-MM , LKML On Mon, Dec 16, 2013 at 2:39 AM, Mel Gorman wrote: > > First was Alex's microbenchmark from https://lkml.org/lkml/2012/5/17/59 > and ran it for a range of thread numbers, 320 iterations per thread with > random number of entires to flush. Results are from two machines There's something wrong with that benchmark, it sometimes gets stuck, and the profile numbers are just random (and mostly in user space). I think you mentioned fixing a bug in it, mind pointing at the fixed benchmark? Looking at the kernel footprint, it seems to depend on what parameters you ran that benchmark with. Under certain loads, it seems to spend most of the time in clearing pages and in the page allocation ("-t 8 -n 320"). And in other loads, it hits smp_call_function_many() and the TLB flushers ("-t 8 -n 8"). So exactly what parameters did you use? Because we've had things that change those two things (and they are totally independent). And does anything stand out in the profiles of ebizzy? For example, in between 3.4.x and 3.11, we've converted the anon_vma locking from a mutex to a rwsem, and we know that caused several issues, possibly causing unfairness. There are other potential sources of unfairness. It would be good to perhaps bisect things at least *somewhat*, because *so* much has changed in 3.4 to 3.11 that it's impossible to guess. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org