From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3CB0B4C7C for ; Fri, 31 May 2024 02:07:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=166.125.252.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717121227; cv=none; b=Phvdmh50kUWhFRLWJHVIXJwgVJGVpWb4JOwVTIaVzeC1AokhKKZPd0Dh4ZYApcH8hKX0r7bFTAtdZPyGBI/SnAvC8ykbzWkJ8mCNbd86/gpWB+AzehTGtGRiiuTvV30WWCfSc7HgAcN5spFNPAAwousV8nN6XO7mqoBrrHAPWsU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717121227; c=relaxed/simple; bh=/gelQHkEy0gA9zQPsWDwqnpmfANPeyIi/aRpF75xs3A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=giSy2a6W4i0Dn34QObyZoOE3/ZHCKlZxE4XoXyonokO+VGY/XIm1yh6fNHtwlB/Ym5EUW5fyLhWHfh/A9QngoYS4kxeXhIJQneeAFpqZpQWglPc20XmKqGYv9Sjtwo6GKS5euzr4EVvgEXN1nSX+rkH/hXPCV8QLtbJD5FXi9dY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-d6dff70000001748-3a-665930c4cb00 Date: Fri, 31 May 2024 11:06:54 +0900 From: Byungchul Park To: Dave Hansen Cc: "Huang, Ying" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, akpm@linux-foundation.org, vernhao@tencent.com, mgorman@techsingularity.net, hughd@google.com, willy@infradead.org, david@redhat.com, peterz@infradead.org, luto@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, rjgolo@gmail.com Subject: Re: [PATCH v10 00/12] LUF(Lazy Unmap Flush) reducing tlb numbers over 90% Message-ID: <20240531020654.GA62639@system.software.com> References: <8734q46jc8.fsf@yhuang6-desk2.ccr.corp.intel.com> <44e4f2fd-e76e-445d-b618-17a6ec692812@intel.com> <20240529050046.GB20307@system.software.com> <961f9533-1e0c-416c-b6b0-d46b97127de2@intel.com> <20240530005026.GA47476@system.software.com> <87a5k814tq.fsf@yhuang6-desk2.ccr.corp.intel.com> <20240530071847.GA15344@system.software.com> <871q5j1zdf.fsf@yhuang6-desk2.ccr.corp.intel.com> <20240530084120.GA12940@system.software.com> <2a0f8cc9-a061-45cd-81df-b65d4b454b77@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2a0f8cc9-a061-45cd-81df-b65d4b454b77@intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrEIsWRmVeSWpSXmKPExsXC9ZZnoe4Rg8g0g65f4hZz1q9hs/i84R+b xaeXDxgtXmxoZ7T4uv4Xs8XTT30sFpd3zWGzuLfmP6vF+V1rWS12LN3HZHHpwAImi+O9B5gs 5t/7zGaxedNUZovjU6YyWvz+AVR8ctZkFgdBj++tfSweO2fdZfdYsKnUY/MKLY/Fe14yeWxa 1cnmsenTJHaPd+fOsXucmPGbxWPeyUCP9/uusnls/WXn0Tj1GpvH501yAXxRXDYpqTmZZalF +nYJXBnH9nSzFuzhqng6+z1rA+Nkji5GTg4JAROJaZ3NjF2MHGD2lhOGIGEWAVWJLac+MIHY bALqEjdu/GQGsUWA7FMrl7N3MXJxMAv0M0v8fwficHIIC4RITPuwBqyBV8BCor+rjQ2kSEjg F7PEs33boBKCEidnPmEBsZkFtCRu/HvJBLKYWUBaYvk/sHs4BWwllq99BLZMVEBZ4sC240wg cyQEtrFLvNj/gh3iaEmJgytusExgFJiFZOwsJGNnIYxdwMi8ilEoM68sNzEzx0QvozIvs0Iv OT93EyMwJpfV/onewfjpQvAhRgEORiUe3oCKiDQh1sSy4srcQ4wSHMxKIry/0oFCvCmJlVWp RfnxRaU5qcWHGKU5WJTEeY2+lacICaQnlqRmp6YWpBbBZJk4OKUaGD1+bEwV4RdRFv/SG2Iq /k94z7S/t/8Kb7jz6sjsY2YsEhyHJ+inbV/Ncd/JTnBdtKt60hzV4MPblvjMtql/u/G6pZOo xJtvaiuWdK24rLFw37yrZgJHvV2qTk0+b/N748/te6sUepPiZGtl5puo97TmRT5ODvBrWuP1 874F266lPyfHOSk8/63EUpyRaKjFXFScCAAry0AExQIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprJIsWRmVeSWpSXmKPExsXC5WfdrHvEIDLN4NcdDos569ewWXze8I/N 4tPLB4wWLza0M1p8Xf+L2eLppz4Wi8NzT7JaXN41h83i3pr/rBbnd61ltdixdB+TxaUDC5gs jvceYLKYf+8zm8XmTVOZLY5Pmcpo8fsHUPHJWZNZHIQ8vrf2sXjsnHWX3WPBplKPzSu0PBbv ecnksWlVJ5vHpk+T2D3enTvH7nFixm8Wj3knAz3e77vK5rH4xQcmj62/7Dwap15j8/i8SS6A P4rLJiU1J7MstUjfLoEr49iebtaCPVwVT2e/Z21gnMzRxcjBISFgIrHlhGEXIycHi4CqxJZT H5hAbDYBdYkbN34yg9giQPaplcvZuxi5OJgF+pkl/r8DcTg5hAVCJKZ9WAPWwCtgIdHf1cYG UiQk8ItZ4tm+bVAJQYmTM5+wgNjMAloSN/69ZAJZzCwgLbH8HwdImFPAVmL52kdgy0QFlCUO bDvONIGRdxaS7llIumchdC9gZF7FKJKZV5abmJljqlecnVGZl1mhl5yfu4kRGGHLav9M3MH4 5bL7IUYBDkYlHt6Aiog0IdbEsuLK3EOMEhzMSiK8v9KBQrwpiZVVqUX58UWlOanFhxilOViU xHm9wlMThATSE0tSs1NTC1KLYLJMHJxSDYwKAg9OznrFZSBt9q1E89n8593iIpde93c1fr7a nmnHl9savZ9N3rb68mLz7M5vl4q6w5mjWI1SPT+8lzi8+NeSqo9dJ38qTgyYzxLW69nD9dMz Z+I9YW75d9OVc7aYsto8Tl17rKHYvrv1coqp5mm9hbuyHiyyZdcxeH8j68vk2x+cWzY6/Fdi Kc5INNRiLipOBAC4rsA8rAIAAA== X-CFilter-Loop: Reflected On Thu, May 30, 2024 at 06:50:48AM -0700, Dave Hansen wrote: > On 5/30/24 01:41, Byungchul Park wrote: > > LUF should not optimize tlb flushes for mappings that users explicitly > > change e.g. through mmap() and munmap(). > > We are thoroughly going around in circles at this point. > > I'm not quite sure what to do. Ying and I see a problem that we've > tried to explain a couple of times. We've tried to show the connection > between a LUF-elided TLB flush and how that could affect a later > munmap() or mmap(MAP_FIXED). > > But these responses seem to keep going back to the fact that LUF doesn't I just wanted to understand exactly what Ying meant. My answer might be done in a wrong way if I wrongly got him. > directly affect munmap(), which is true, but quite irrelevant to the > problem being described. > > So we're at an impasse. > > Byungchul, perhaps you should spin another series and maybe Ying and I I don't think the current implementation is perfect. I just wanted to know what I'm missing now but.. yes. It would be much better to communicate with a real bug if existing. I will respin the next version shortly. Byungchul > have to write up a test case to show the bug that we see. Or perhaps > someone else can jump into the thread and bridge the communication gap.