From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by kanga.kvack.org (Postfix) with ESMTP id 0BD738E0002 for ; Thu, 3 Jan 2019 12:11:00 -0500 (EST) Received: by mail-pg1-f200.google.com with SMTP id g188so28998547pgc.22 for ; Thu, 03 Jan 2019 09:11:00 -0800 (PST) Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com. [115.124.30.130]) by mx.google.com with ESMTPS id u129si33161097pfu.117.2019.01.03.09.10.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 03 Jan 2019 09:10:58 -0800 (PST) Subject: Re: [v4 PATCH 1/2] mm: swap: check if swap backing device is congested or not References: <1546145375-793-1-git-send-email-yang.shi@linux.alibaba.com> <20190102230054.m5ire5gdhm5fzecq@ca-dmjordan1.us.oracle.com> From: Yang Shi Message-ID: <76d8727a-77b4-d476-af89-9ae1904ec8cd@linux.alibaba.com> Date: Thu, 3 Jan 2019 09:10:13 -0800 MIME-Version: 1.0 In-Reply-To: <20190102230054.m5ire5gdhm5fzecq@ca-dmjordan1.us.oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Daniel Jordan Cc: ying.huang@intel.com, tim.c.chen@intel.com, minchan@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On 1/2/19 3:00 PM, Daniel Jordan wrote: > On Sun, Dec 30, 2018 at 12:49:34PM +0800, Yang Shi wrote: >> The test on my virtual machine with congested HDD shows long tail >> latency is reduced significantly. >> >> Without the patch >> page_fault1_thr-1490 [023] 129.311706: funcgraph_entry: #57377.796 us | do_swap_page(); >> page_fault1_thr-1490 [023] 129.369103: funcgraph_entry: 5.642us | do_swap_page(); >> page_fault1_thr-1490 [023] 129.369119: funcgraph_entry: #1289.592 us | do_swap_page(); >> page_fault1_thr-1490 [023] 129.370411: funcgraph_entry: 4.957us | do_swap_page(); >> page_fault1_thr-1490 [023] 129.370419: funcgraph_entry: 1.940us | do_swap_page(); >> page_fault1_thr-1490 [023] 129.378847: funcgraph_entry: #1411.385 us | do_swap_page(); >> page_fault1_thr-1490 [023] 129.380262: funcgraph_entry: 3.916us | do_swap_page(); >> page_fault1_thr-1490 [023] 129.380275: funcgraph_entry: #4287.751 us | do_swap_page(); >> >> With the patch >> runtest.py-1417 [020] 301.925911: funcgraph_entry: #9870.146 us | do_swap_page(); >> runtest.py-1417 [020] 301.935785: funcgraph_entry: 9.802us | do_swap_page(); >> runtest.py-1417 [020] 301.935799: funcgraph_entry: 3.551us | do_swap_page(); >> runtest.py-1417 [020] 301.935806: funcgraph_entry: 2.142us | do_swap_page(); >> runtest.py-1417 [020] 301.935853: funcgraph_entry: 6.938us | do_swap_page(); >> runtest.py-1417 [020] 301.935864: funcgraph_entry: 3.765us | do_swap_page(); >> runtest.py-1417 [020] 301.935871: funcgraph_entry: 3.600us | do_swap_page(); >> runtest.py-1417 [020] 301.935878: funcgraph_entry: 7.202us | do_swap_page(); > Hi Yang, I guess runtest.py just calls page_fault1_thr? Being explicit about Yes, runtest.py is the wrapper script of will-it-scale. > this may improve the changelog for those unfamiliar with will-it-scale. Sure. > > May also be useful to name will-it-scale and how it was run (#thr, runtime, > system cpus/memory/swap) for more context. How about the below description: The test with page_fault1 of will-it-scale (sometimes tracing may just show runtest.py that is the wrapper script of page_fault1), which basically launches NR_CPU threads to generate 128MB anonymous pages for each thread,  on my virtual machine with congested HDD shows long tail latency is reduced significantly. Without the patch  page_fault1_thr-1490  [023]   129.311706: funcgraph_entry: #57377.796 us |  do_swap_page();  page_fault1_thr-1490  [023]   129.369103: funcgraph_entry: 5.642us   |  do_swap_page();  page_fault1_thr-1490  [023]   129.369119: funcgraph_entry: #1289.592 us |  do_swap_page();  page_fault1_thr-1490  [023]   129.370411: funcgraph_entry: 4.957us   |  do_swap_page();  page_fault1_thr-1490  [023]   129.370419: funcgraph_entry: 1.940us   |  do_swap_page();  page_fault1_thr-1490  [023]   129.378847: funcgraph_entry: #1411.385 us |  do_swap_page();  page_fault1_thr-1490  [023]   129.380262: funcgraph_entry: 3.916us   |  do_swap_page();  page_fault1_thr-1490  [023]   129.380275: funcgraph_entry: #4287.751 us |  do_swap_page(); With the patch       runtest.py-1417  [020]   301.925911: funcgraph_entry: #9870.146 us |  do_swap_page();       runtest.py-1417  [020]   301.935785: funcgraph_entry: 9.802us   |  do_swap_page();       runtest.py-1417  [020]   301.935799: funcgraph_entry: 3.551us   |  do_swap_page();       runtest.py-1417  [020]   301.935806: funcgraph_entry: 2.142us   |  do_swap_page();       runtest.py-1417  [020]   301.935853: funcgraph_entry: 6.938us   |  do_swap_page();       runtest.py-1417  [020]   301.935864: funcgraph_entry: 3.765us   |  do_swap_page();       runtest.py-1417  [020]   301.935871: funcgraph_entry: 3.600us   |  do_swap_page();       runtest.py-1417  [020]   301.935878: funcgraph_entry: 7.202us   |  do_swap_page(); Thanks, Yang