From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from invmail4.hynix.com (exvmail4.hynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 37CD64C8C for ; Thu, 23 May 2024 02:05:46 +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=1716429953; cv=none; b=T6j6YdQqRoyxJ7Yw3NkSzmMTu/6ClucjyxdqpE+Y5pFZSYqHFSM+NPDNLzUPbhTHj6jjxIXzfO3gXM6HvgyQNWT+qwNCELCwCamgznOdkyzyDZK1nkyotm/kldl7bZVmO+EIKAKddgMg1TjPdC6emJb1ukFhcEAKOar0JINryAI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716429953; c=relaxed/simple; bh=F0zJvS8EDjOOjkiSmJbJ0GSUuxIY/vMkpLOBll5ON2I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=l8UziikQzbRtqb5yG2s0cFo8cP73D3nvMz1Kw7LFQsstX8EPIHbspdWLfg/M2Qr5hbJXxYvuFk4Tnmyjpz1JRPTKUjnHMqnNn7AcRpL6toZnYgQMprJSMFORoRFja924y7y7ebYZ0wRu1DLJWT7jfx1qUgbOr0BceRyhyN3ruiw= 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-d6dff70000001748-71-664ea4793e2c Date: Thu, 23 May 2024 11:05:39 +0900 From: Byungchul Park To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, ying.huang@intel.com, 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: [RESEND PATCH v10 00/12] LUF(Lazy Unmap Flush) reducing tlb numbers over 90% Message-ID: <20240523020539.GA21061@system.software.com> References: <20240520021734.21527-1-byungchul@sk.com> <20240522155641.a726c5cd3b25aa23e861045d@linux-foundation.org> 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: <20240522155641.a726c5cd3b25aa23e861045d@linux-foundation.org> User-Agent: Mutt/1.9.4 (2018-02-28) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrNIsWRmVeSWpSXmKPExsXC9ZZnkW7lEr80g9/PhS3mrF/DZvF5wz82 ixcb2hktvq7/xWzx9FMfi8XlXXPYLO6t+c9qcX7XWlaLHUv3MVlcOrCAyeJ47wEmi/n3PrNZ bN40ldni+JSpjBa/fwAVn5w1mcVBwON7ax+Lx85Zd9k9Fmwq9di8Qstj8Z6XTB6bVnWyeWz6 NInd4925c+weJ2b8ZvGYdzLQ4/2+q2weW3/ZeTROvcbm8XmTXABfFJdNSmpOZllqkb5dAlfG j+tHWAu6+Sp6l2Q0ME7i7mLk5JAQMJHYcOo3M4z9recySxcjBweLgKrElquBIGE2AXWJGzd+ gpWICOhKrHq+C8jm4mAWeMQksfzjKjaQhLBAtMTD689ZQWxeAQuJrSvugsWFBMokHsw4ywIR F5Q4OfMJmM0soCVx499LJpBdzALSEsv/cYCEOQW8JV7Ma2cEsUUFlCUObDvOBLJLQmAVu8SH Dbeg7pSUOLjiBssERoFZSMbOQjJ2FsLYBYzMqxiFMvPKchMzc0z0MirzMiv0kvNzNzECo3BZ 7Z/oHYyfLgQfYhTgYFTi4e2Q9UsTYk0sK67MPcQowcGsJMIbvdI3TYg3JbGyKrUoP76oNCe1 +BCjNAeLkjiv0bfyFCGB9MSS1OzU1ILUIpgsEwenVAPj+vyZRfpVOQFM01NmFimulm8/E3FL 1tNiofG/5uMcvjcyt/Lmvt3yujHxd9ktMabteeJ/XvyI/Dy7oEh5k4pyySwpma6eL/ZRgWeu /67nT3H9IrjwhZrl5EP+U157hXRE9AgF3/KNOCzA2Pxc7g+HxVvzCd/DTX8+aH+d/XNL36yD NRnPxKYrsRRnJBpqMRcVJwIAR89vRL4CAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprEIsWRmVeSWpSXmKPExsXC5WfdrFu5xC/N4OJbVos569ewWXze8I/N 4sWGdkaLr+t/MVs8/dTHYnF47klWi8u75rBZ3Fvzn9Xi/K61rBY7lu5jsrh0YAGTxfHeA0wW 8+99ZrPYvGkqs8XxKVMZLX7/ACo+OWsyi4Ogx/fWPhaPnbPusnss2FTqsXmFlsfiPS+ZPDat 6mTz2PRpErvHu3Pn2D1OzPjN4jHvZKDH+31X2TwWv/jA5LH1l51H49RrbB6fN8kF8Edx2aSk 5mSWpRbp2yVwZfy4foS1oJuvondJRgPjJO4uRk4OCQETiW89l1m6GDk4WARUJbZcDQQJswmo S9y48ZMZxBYR0JVY9XwXkM3FwSzwiEli+cdVbCAJYYFoiYfXn7OC2LwCFhJbV9wFiwsJlEk8 mHGWBSIuKHFy5hMwm1lAS+LGv5dMILuYBaQllv/jAAlzCnhLvJjXzghiiwooSxzYdpxpAiPv LCTds5B0z0LoXsDIvIpRJDOvLDcxM8dUrzg7ozIvs0IvOT93EyMwppbV/pm4g/HLZfdDjAIc jEo8vAm/fNOEWBPLiitzDzFKcDArifBGrwQK8aYkVlalFuXHF5XmpBYfYpTmYFES5/UKT00Q EkhPLEnNTk0tSC2CyTJxcEo1MJp/DVIM+/81U2q92knPRetnnz10Py323pKOP1zeC5XNZdgj m+Jnhr/8r3ts110nZ2PBk77x//0Y/Ru/f3zeX6Bic1mORZV/STOHwHTeUqeoG0XBjc2pK08t 6fo69Z+m5oqzb28ur1eN6U891Grr9PSDpatbdXbMrD8WK2e/zlFbcJTn3P2tXUosxRmJhlrM RcWJAFm7ha6lAgAA X-CFilter-Loop: Reflected On Wed, May 22, 2024 at 03:56:41PM -0700, Andrew Morton wrote: > On Mon, 20 May 2024 11:17:22 +0900 Byungchul Park wrote: > > > While I'm working with a tiered memory system e.g. CXL memory, I have > > been facing migration overhead esp. tlb shootdown on promotion or > > demotion between different tiers. Yeah.. most tlb shootdowns on > > migration through hinting fault can be avoided thanks to Huang Ying's > > work, commit 4d4b6d66db ("mm,unmap: avoid flushing tlb in batch if PTE > > is inaccessible"). See the following link for more information: > > > > https://lore.kernel.org/lkml/20231115025755.GA29979@system.software.com/ > > > > However, it's only for migration through hinting fault. I thought it'd > > be much better if we have a general mechanism to reduce all the tlb > > numbers that we can apply to any unmap code, that we normally believe > > tlb flush should be followed. > > > > I'm suggesting a new mechanism, LUF(Lazy Unmap Flush), defers tlb flush > > until folios that have been unmapped and freed, eventually get allocated > > again. It's safe for folios that had been mapped read-only and were > > unmapped, since the contents of the folios don't change while staying in > > pcp or buddy so we can still read the data through the stale tlb entries. > > Version 10 and no reviewed-by's or acked-by's. Reviewing the review > history isn't helped by the change in the naming of the patch series. > > Seems that you're measuring a ~5% overall speedup in a realistic > workload? That's nice. > > I'll defer this for a week or so to see what reviewers have to say. If > "nothing", please poke me and I guess I'll merge it up to see what I will poke you and will be ready for that ;) Byungchul > happens ;)