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 4ECAF148848 for ; Tue, 30 Jul 2024 16:31:03 +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=1722357064; cv=none; b=E5I1IhnpOroxbvLBFTcyvF2KQ5Z6x8zt6dEuBV3ueZ+5BbaoZuSEoypm6ULE9vUvx+TokCYQ1IfmIUFxgrBrsRLDyTYO8uHz07STHqnWPGAVA2Wy5vHIgVn0ZILdAmhIc0Ew0ACGNdZGpJp+5mESl9THL8soEWIzhaMWshD3IUo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722357064; c=relaxed/simple; bh=+C0E1OanNPR6JWfsgQVFSr3T1t2R3zLqnhwmlGBvsGY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=vCYJC5OuviAJM0LRDh6mMyHP/oiKuhL0WMVmLoO3yjnKmNrWAzmWzdRLMEuxydEIS5QWmc6O6ue3rRJik675EUXkkRRjAONX2MN/ouyzENAMpMkjvg0ATOolFmKrx5raile5kc+dgMjRiSKbak01Yi120qBPHDPrHyY8gHihsIg= 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=qeWQC7lG; 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="qeWQC7lG" 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=N4r8fij+5bYAfmVEXguco28K5EokHtUd/W88ZrJncUY=; b=qeWQC7lGs9fCpnbeNdovZWG2IO YQmngMkI7RN3B6jmz3kwZeQ4HjCYuanpLQ3nWU478I87lU90puzIl1TkbFf2wjp3IOGXRtSSTfB0X iHCTeW82Ph+tjAWBfIhyOQzkiyf+Q5GLgoTYpX8UN++PzYJ7sfqhxdfEE/stM+5RYE+Glrh1O0CC5 P1A5JqjLGjalpkEDJew8xUpEilkvicXaSDCSX8tW7ciZFGKeCPsg5E3vo3rEuV7MOI1IZ/unH3Mkn a4Bhvdp9hQmW7ObigGHIG2haniKb99l02AYoCemyOfFhi1tIPptj/t1GL7s8+HNg320t1YqFXAsf4 NWmdnBJg==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sYpkI-0000000Fs5L-0pMd; Tue, 30 Jul 2024 16:30:42 +0000 Date: Tue, 30 Jul 2024 09:30:42 -0700 From: Christoph Hellwig To: Barry Song <21cnbao@gmail.com> Cc: Christoph Hellwig , Matthew Wilcox , akpm@linux-foundation.org, linux-mm@kvack.org, ying.huang@intel.com, baolin.wang@linux.alibaba.com, chrisl@kernel.org, david@redhat.com, hannes@cmpxchg.org, hughd@google.com, kaleshsingh@google.com, kasong@tencent.com, linux-kernel@vger.kernel.org, mhocko@suse.com, minchan@kernel.org, nphamcs@gmail.com, ryan.roberts@arm.com, senozhatsky@chromium.org, shakeel.butt@linux.dev, shy828301@gmail.com, surenb@google.com, v-songbaohua@oppo.com, xiang@kernel.org, yosryahmed@google.com Subject: Re: [PATCH v5 4/4] mm: Introduce per-thpsize swapin control policy Message-ID: References: <20240726094618.401593-1-21cnbao@gmail.com> <20240726094618.401593-5-21cnbao@gmail.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: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Jul 30, 2024 at 08:11:16AM +1200, Barry Song wrote: > > We also really need to stop optimizing for this weird zram case and move > > people to zswap instead after fixing the various issues. A special > > block device that isn't really a block device and needs various special > > hooks isn't the right abstraction for different zwap strategies. > > My understanding is zRAM is much more popularly used in embedded > systems than zswap. I seldomly(or never) hear who is using zswap > in Android. it seems pointless to force people to move to zswap, in > embedded systems we don't have a backend real block disk device > after zswap. Well, that is the point. zram is a horrible hack that abuses a block device to implement a feature missing the VM layer. Right now people have a reason for it because zswap requires a "real" backing device and that's fine for them and for now. But instead of building VM infrastructure around these kinds of hacks we need to fix the VM infrastructure. Chris Li has been talking about and working towards a proper swap abstraction and that needs to happen.