From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga06.intel.com ([134.134.136.31]:49414 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727054AbeH2KvW (ORCPT ); Wed, 29 Aug 2018 06:51:22 -0400 From: "Huang\, Ying" To: Josef Bacik Cc: Josef Bacik , Chris Mason , David Sterba , , Subject: Re: [LKP] [lkp-robot] [mm] 9092c71bb7: blogbench.write_score -12.3% regression References: <20180408015739.GN3845@yexl-desktop> <876036apgx.fsf@yhuang-dev.intel.com> <878t7t3k3s.fsf@yhuang-dev.intel.com> <87h8m6m9ld.fsf@yhuang-dev.intel.com> <878t7ai08v.fsf@yhuang-dev.intel.com> <87zhyvew74.fsf@yhuang-dev.intel.com> <87tvod8g8k.fsf@yhuang-dev.intel.com> <20180802162330.bs3irlc5hqq75ukp@destiny> <871sbf7tcf.fsf@yhuang-dev.intel.com> Date: Wed, 29 Aug 2018 14:55:56 +0800 In-Reply-To: <871sbf7tcf.fsf@yhuang-dev.intel.com> (Ying Huang's message of "Fri, 3 Aug 2018 16:22:08 +0800") Message-ID: <875zztacg3.fsf@yhuang-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Sender: linux-btrfs-owner@vger.kernel.org List-ID: "Huang, Ying" writes: > Josef Bacik writes: > >> On Thu, Aug 02, 2018 at 01:55:23PM +0800, Huang, Ying wrote: >>> "Huang, Ying" writes: >>> >>> > Hi, Chris, >>> > >>> > Chris Mason writes: >>> > >>> >> On 19 Jun 2018, at 23:51, Huang, Ying wrote: >>> >>>>> "Huang, Ying" writes: >>> >>>>> >>> >>>>>> Hi, Josef, >>> >>>>>> >>> >>>>>> Do you have time to take a look at the regression? >>> >>>>>> >>> >>>>>> kernel test robot writes: >>> >>>>>> >>> >>>>>>> Greeting, >>> >>>>>>> >>> >>>>>>> FYI, we noticed a -12.3% regression of blogbench.write_score and >>> >>>>>>> a +9.6% improvement >>> >>>>>>> of blogbench.read_score due to commit: >>> >>>>>>> >>> >>>>>>> >>> >>>>>>> commit: 9092c71bb724dba2ecba849eae69e5c9d39bd3d2 ("mm: use >>> >>>>>>> sc->priority for slab shrink targets") >>> >>>>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git >>> >>>>>>> master >>> >>>>>>> >>> >>>>>>> in testcase: blogbench >>> >>>>>>> on test machine: 16 threads Intel(R) Xeon(R) CPU D-1541 @ >>> >>>>>>> 2.10GHz with 8G memory >>> >>>>>>> with following parameters: >>> >>>>>>> >>> >>>>>>> disk: 1SSD >>> >>>>>>> fs: btrfs >>> >>>>>>> cpufreq_governor: performance >>> >>>>>>> >>> >>>>>>> test-description: Blogbench is a portable filesystem benchmark >>> >>>>>>> that tries to reproduce the load of a real-world busy file >>> >>>>>>> server. >>> >>>>>>> test-url: >>> >> >>> >> I'm surprised, this patch is a big win in production here at FB. I'll >>> >> have to reproduce these results to better understand what is going on. >>> >> My first guess is that since we have fewer inodes in slab, we're >>> >> reading more inodes from disk in order to do the writes. >>> >> >>> >> But that should also make our read scores lower. >>> > >>> > Any update on this? >>> >>> Ping. >>> >> >> I can't reproduce this, and what's more it appears that blogbench doesn't use >> much memory at all. I have the slab shrinking tracepoints on and we never go >> into this code at all, so I'm pretty sure these results are bogus. How are you >> running blogbench? I'm doing blogbench -d /whatever, if I need to be doing >> something else let me know. But from what I can tell this thing uses less than >> 100m of memory, and on an 8gig of ram box we're never going to trip over this >> code. Thanks, > > Thanks for looking at this. In my testing, blogbench will eat up system > memory. Please check the vmstat result attached. The SSD disk size is > about 745GB. Hi, Josef, Do you need more information? Best Regards, Huang, Ying > Best Regards, > Huang, Ying