From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f71.google.com (mail-pa0-f71.google.com [209.85.220.71]) by kanga.kvack.org (Postfix) with ESMTP id 098836B0005 for ; Thu, 16 Jun 2016 16:24:25 -0400 (EDT) Received: by mail-pa0-f71.google.com with SMTP id b13so99423204pat.3 for ; Thu, 16 Jun 2016 13:24:25 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTP id h62si7657231pfb.176.2016.06.16.13.24.24 for ; Thu, 16 Jun 2016 13:24:24 -0700 (PDT) Subject: Re: [PATCH v3] Linux VM workaround for Knights Landing A/D leak References: <1465923672-14232-1-git-send-email-lukasz.anaczkowski@intel.com> <1466090042-30908-1-git-send-email-lukasz.anaczkowski@intel.com> From: Dave Hansen Message-ID: <57630ADE.3040900@linux.intel.com> Date: Thu, 16 Jun 2016 13:23:58 -0700 MIME-Version: 1.0 In-Reply-To: <1466090042-30908-1-git-send-email-lukasz.anaczkowski@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Lukasz Anaczkowski , hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, ak@linux.intel.com, kirill.shutemov@linux.intel.com, mhocko@suse.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: harish.srinivasappa@intel.com, lukasz.odzioba@intel.com, grzegorz.andrejczuk@intel.com, lukasz.daniluk@intel.com On 06/16/2016 08:14 AM, Lukasz Anaczkowski wrote: > For reclaim this brings the performance back to before Mel's > flushing changes, but for unmap it disables batching. This turns out to be pretty catastrophic for unmap. In a workload that uses, say 200 hardware threads and alloc/frees() a few MB/sec, this ends up costing hundreds of thousands of extra received IPIs. 10MB=~2500 ptes, and at with 200 threads, that's 250,000 IPIs received just to free 10MB of memory. The initial testing we did on this was on a *bunch* of threads all doing alloc/free. But this is bottlenecked on other things, like mmap_sem being held for write. The scenario that we really needed to test here was on lots of threads doing processing and 1 thread doing alloc/free. -- 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