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 782AF29AB; Mon, 1 Jul 2024 04:49:08 +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=1719809350; cv=none; b=cqMcrSIdv0yvW8XPH/IMFrLyX4m+ifvsmTPtZ1ZX82SmhWp4sWPJ+1j1Hr9I3fnPU43/F1CMpVWHWN0zssP0IGfbizsWHu9Cr5HD66tedYUMtNOSNzTTL253BfWINN10WFj4YHF7TB7hxaBxn8c4mK+OD0nt9gR0KpoB/yFgte0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719809350; c=relaxed/simple; bh=Ziwncewm+F+7gGP6+/X0T5LH1JruUDCDKDS46s+vRsM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iKIvH8dk3RuHaTHKMNuXihlumK9HBFIVlh8542KtasecAmR50K3QAFbDLrfg6kNxgBZlsl1h43HntblGxYCcTeno2hmPiG7hnwk2ELkVauAfDeqeOxjNa1d6A/DSOmXvZ+JCSvuK0nI8P8eOd/yo3WjXiWEmVt7xfeaGDcMtx1I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=H96fLQ+Q; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="H96fLQ+Q" 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=xsAvaJIxk4Rm8dv5j1no/y+ULSGMMDw+74ymp2w0nIA=; b=H96fLQ+QKiwqmvJQWeYXlBCzu8 xPWqDwlofx2xbrvbPg+o1eCBoPFj3csh0N9QsVvQCe1dtSv6DVlWHWTLLX+VgJJl2QB6dxxNKjpCd LqbRzWWv/owOEJI6YLVaowVdAENELB/dQP5VIYv2dGntTi71yhJNXtC7gwe4AUOM/+vjxCR1tt4/m VJ39qnanU/WN+PcspEnlZx1OU5j3QJ5TvHqsjCtK8mSbRxrCVECGpu5UvbS9gXQdISGZCHeRPft34 9gQT4Of3b50ePpCODx0bhFPXTW6SEF+09LCj40kCQ5JdEKrGMIu3nuZuSbeu26UoPnRNwatFWUiK1 wsn4MjaQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sO8yN-00000001ge7-1zGd; Mon, 01 Jul 2024 04:49:03 +0000 Date: Sun, 30 Jun 2024 21:49:03 -0700 From: Christoph Hellwig To: Dave Chinner Cc: alexjlzheng@gmail.com, chandan.babu@oracle.com, djwong@kernel.org, hch@infradead.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, alexjlzheng@tencent.com Subject: Re: [PATCH v3 2/2] xfs: make xfs_log_iovec independent from xfs_log_vec and free it early Message-ID: References: <20240626044909.15060-1-alexjlzheng@tencent.com> <20240626044909.15060-3-alexjlzheng@tencent.com> Precedence: bulk X-Mailing-List: linux-xfs@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: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Jul 01, 2024 at 10:51:13AM +1000, Dave Chinner wrote: > Here's the logic - the iovec array is largely "free" with the larger > data allocation. What the patch does it to free the data allocation, that is the shadow buffer earlier. Which would safe a quite a bit of memory indeed ... if we didn't expect the shadow buffer to be needed again a little later anyway, which AFAIK is the assumption under which the CIL code operates. So as asked previously and by you again here I'd love to see numbers for workloads where this actually is a benefit.