From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C901B38A722 for ; Tue, 25 Aug 2026 07:52:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787644357; cv=none; b=lupNjVyHowb/bVc1e3uuDf6FGyAx0QqW+HR6Cs5XY/RzpXYOoVyYS5OZ4RjlO7b24CeVZD0jWswTUF6R5KaC3c04a+vz1dGSOC9c9ZUBE0CBMM4xohkBX4tn0ZQZqc5Xro4Se+L7YxDtDX2d2bLATNcu2jC57VE7ZL84aDxPEVY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787644357; c=relaxed/simple; bh=24ztbUVV9ettc0ciyNwXgJ8hrxryu/dV328dLviwKI0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=H/Mg5na/vXyR4AC7AW7ZrNoAwttUecLxO0vgoLORE5h6+hooeSLLFOnPN2qCoqle0a37dglg03TWKyA/PlDwA6LXB+t1Ft/95TSfGpJhHa5dz/9G7rkP54uaLGI0XJGFULrP9FtUgOst7orE2JZ/CIf9wCKkdki8pD903O8eL+A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=memm6yJk; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="memm6yJk" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=CVaLUtmQZ+lo3k9HI0lk+lS5cr/55GIIaizc2rZZWKY=; b=memm6yJkJ4ijgsuHxHuws1dYrr +Beq6HH2viHZjubrWi+Tff+e1aq9+Z+4rmfokFIYkKv6i88fkaOPhsWgBpNKHrPXJApgkqJSyYrp1 yu00hhqvIitnnPtHUQGeHgEDgu6Sk2IBdrBzfKKCjzQUDdxWOlpuN9ECd73zQaJ8rOi0rNjY2UEQF MhyVgzjD7/jwgDmGUCwlgP7lPpla5buCo6dQQIFgkISXUcKo4XjMIlduqC+yMiB+3g7hiQqvbEmC6 Kgtv0m/GIHGB2xsHVWz+3jGKO4XH/4rNRfvHSK4755aL36Aeiu5INcKBOAWSYiyPWdjdllBLzFtOw yEF1Bhcw==; Received: from hch by bombadil.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1wylxQ-00000000K5L-36MN; Tue, 25 Aug 2026 07:52:32 +0000 Date: Tue, 25 Aug 2026 00:52:32 -0700 From: Christoph Hellwig To: Rik van Riel Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, Andrew Morton , David Hildenbrand , Jason Gunthorpe , John Hubbard , Peter Xu , linux-mm@kvack.org Subject: Re: [RFC PATCH v3 0/8] batch lookups in follow_page_mask() Message-ID: References: <20260811025157.1632867-1-riel@surriel.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: <20260811025157.1632867-1-riel@surriel.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Aug 10, 2026 at 10:51:49PM -0400, Rik van Riel wrote: > follow_page_mask() walks the page tables one page at a time, even when the > caller asked for a whole run of contiguous pages. Every page of a large folio > re-enters the pmd/pud/pte walk and re-takes the page table lock. > > This series changes follow_page_mask() to return a page count and a fill an > array of pages, instead of a single struct page, so a walker can hand back > more than one page per call. And what many including the most performance critical callers want instead is really a single bio_vec. Maybe we can go the extra step for that, as it would reduce the number of calls into gup significantly.