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AJvYcCWWsc58gtHLNpH9CAa7rTwx4Jz1T5aT27SQU1+ALAS9Hhl2nzqE/l7crQafp7TklDJ4hNLuBosT0Q==@kvack.org X-Gm-Message-State: AOJu0Yy4jE/2ePEm547TuUirczjH6lBeRkuhCk23Gdiheo0NdnUjl3Hc 1GDRgIWW0Uol2a4PkoNDX0NCLNPbsRZJu/7slyicf7gX/8souIEd/bvPxb/Ccmdt0Kkh6eFsfV2 lw3SfOZtWq4DO3ymcvMiyvkgSyEyRmHThYqT424JQ X-Gm-Gg: ASbGncsopz6t9QR1ugKMumN9T+AIoggQigVY5FStp3AU1MkGx3ty7QPkBHUZU7TxweT 4jXclD3xGFs6kdTEXRLsBS4mWxTRGZjDbAbJOsRXImmoS9MgW2fBovn+q6KnWsWXDVQYj0lje7Z izB65dWbmEtVdTSO0fV+mHeErzYMW+lJE2AJbwn1iyCgQ/cRBzQG+hYjPB04szP6RgeCc1IrAPH 2lz/0PNcOr/OoRJsNW9Tip+ULYBwKVY/GM= X-Google-Smtp-Source: AGHT+IEvIyaewpd1z50G14jfP2i5jSv0GcxRpXNr+oXtWD/QgpMt2hhkcUb0kWVZEwAn2vN3hoIdh8YmyHA5+kYPcBI= X-Received: by 2002:a50:aa95:0:b0:607:d206:7657 with SMTP id 4fb4d7f45d1cf-617e152e274mr1175a12.2.1754588294999; Thu, 07 Aug 2025 10:38:14 -0700 (PDT) MIME-Version: 1.0 References: <202508071609.4e743d7c-lkp@intel.com> <9e3a59b2-11c0-43ca-aff3-414091f04aa4@lucifer.local> In-Reply-To: <9e3a59b2-11c0-43ca-aff3-414091f04aa4@lucifer.local> From: Jann Horn Date: Thu, 7 Aug 2025 19:37:38 +0200 X-Gm-Features: Ac12FXzlXycSMR6_C9Cle-BO1qGA01-IsNhuqseD9fQKbf1SHEDGINCkLu6Sek0 Message-ID: Subject: Re: [linus:master] [mm] f822a9a81a: stress-ng.bigheap.realloc_calls_per_sec 37.3% regression To: Lorenzo Stoakes Cc: kernel test robot , Dev Jain , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Andrew Morton , Barry Song , Pedro Falcato , Anshuman Khandual , Bang Li , Baolin Wang , bibo mao , David Hildenbrand , Hugh Dickins , Ingo Molnar , Lance Yang , Liam Howlett , Matthew Wilcox , Peter Xu , Qi Zheng , Ryan Roberts , Vlastimil Babka , Yang Shi , Zi Yan , linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 14476180007 X-Stat-Signature: w438761b93ordq7za34cqibj4485qtf6 X-Rspam-User: X-HE-Tag: 1754588296-833876 X-HE-Meta: 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 bjx5jA/K U6Cg/yN2t8tIbRmj2vxf9BYuaAvlQt+DL24z6l+za0Yk9FFpkK4w/TM02c8z6M+dZrYSNkXuEyHhvZQvb1knoBceIZeatdxMUmraz95TJSZe4ghM2wIUwiq4u+c6uPSo08Jm5VE3zFf/BuR1aq/DyPg+SblxdOh2ITqB20eD3le5bc8pJH+WOSmFBuviUK+U6VbbI22kv/82WF0VJmkXtCH/R3qz/F0TZigxUaeHvh0FUzE3vBuKsBq7qqhzCSAB5UxjybEwzEXx7pWK8N2lY/jObFTLF4FLgvUoW1LH9ghPwWcVwi9lWYPgrXg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 7, 2025 at 10:28=E2=80=AFAM Lorenzo Stoakes wrote: > On Thu, Aug 07, 2025 at 04:17:09PM +0800, kernel test robot wrote: > > 94dab12d86cf77ff f822a9a81a31311d67f260aea96 > > ---------------- --------------------------- > > %stddev %change %stddev > > \ | \ > > 13777 =C4=85 37% +45.0% 19979 =C4=85 27% numa-vmstat.nod= e1.nr_slab_reclaimable > > 367205 +2.3% 375703 vmstat.system.in > > 55106 =C4=85 37% +45.1% 79971 =C4=85 27% numa-meminfo.no= de1.KReclaimable > > 55106 =C4=85 37% +45.1% 79971 =C4=85 27% numa-meminfo.no= de1.SReclaimable > > 559381 -37.3% 350757 stress-ng.bigheap.realloc= _calls_per_sec > > 11468 +1.2% 11603 stress-ng.time.system_tim= e > > 296.25 +4.5% 309.70 stress-ng.time.user_time > > 0.81 =C4=85187% -100.0% 0.00 perf-sched.sch_delay= .avg.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0 > > 9.36 =C4=85165% -100.0% 0.00 perf-sched.sch_delay= .max.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0 > > 0.81 =C4=85187% -100.0% 0.00 perf-sched.wait_time= .avg.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0 > > 9.36 =C4=85165% -100.0% 0.00 perf-sched.wait_time= .max.ms.__cond_resched.zap_pte_range.zap_pmd_range.isra.0 > > 5.50 =C4=85 17% +390.9% 27.00 =C4=85 56% perf-c2c.DRAM.l= ocal > > 388.50 =C4=85 10% +114.7% 834.17 =C4=85 33% perf-c2c.DRAM.r= emote > > 1214 =C4=85 13% +107.3% 2517 =C4=85 31% perf-c2c.HITM.l= ocal > > 135.00 =C4=85 19% +130.9% 311.67 =C4=85 32% perf-c2c.HITM.r= emote > > 1349 =C4=85 13% +109.6% 2829 =C4=85 31% perf-c2c.HITM.t= otal > > Yeah this also looks pretty consistent too... FWIW, HITM hat different meanings depending on exactly which microarchitecture that test happened on; the message says it is from Sapphire Rapids, which is a successor of Ice Lake, so HITM is less meaningful than if it came from a pre-IceLake system (see https://lore.kernel.org/all/CAG48ez3RmV6SsVw9oyTXxQXHp3rqtKDk2qwJWo9TGvXCq7= Xr-w@mail.gmail.com/). To me those numbers mainly look like you're accessing a lot more cache-cold data. (On pre-IceLake they would indicate cacheline bouncing, but I guess here they probably don't.) And that makes sense, since before the patch, this path was just moving PTEs around without looking at the associated pages/folios; basically more or less like a memcpy() on x86-64. But after the patch, for every 8 bytes that you copy, you have to load a cacheline from the vmemmap to get the page.