From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f177.google.com (mail-pf1-f177.google.com [209.85.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B1D24120B for ; Thu, 26 Sep 2024 04:41:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727325695; cv=none; b=Pnl413w5gvqjDX+/4gewVPzTF44IgVdHGWoh/8bt9ojJf7WRkvLISZh9FENtY8zuK/NOgP5e7FYrU5Jq5jtnBgkQ5mfKLIxw4Wwy7ay1U+Ss2ozZAlIg+kL8qHoSt2XRZam/6/gt8xG1bIDbzO6AnfNXNtSBYd607CPUAPdQ0r8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727325695; c=relaxed/simple; bh=tWHyjY9HXACvx+Bs69UkAw2f+LmrsvPg2gVTucv/eoU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=M4zUX42Kvr7+cPUHMcy4EzQ8Rf9Xi7M4gbpkTD9LjJmw/IQTzN70VGpfIMWDDkKqRV0uSxuRGIb88viqDaL1MIrmweHCbCNZ2C3qnzD9gjTOLCotlgfbshtB8+OjL9JhMFxcg1jbuKSazGxgmGns2BjqtP4F3QycQLfiqpcvBHk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=RmcdBckm; arc=none smtp.client-ip=209.85.210.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="RmcdBckm" Received: by mail-pf1-f177.google.com with SMTP id d2e1a72fcca58-718816be6cbso515962b3a.1 for ; Wed, 25 Sep 2024 21:41:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1727325694; x=1727930494; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=/IK77nxbBZEPITpwoYAt/gwthd7nkAtPQWQqMMDw4Ls=; b=RmcdBckmPA2o+i1BJkyHIfl+b6bwMYscOe72t2pPEtKtmu6AwI5Te9v3cTQtBcN7nY FMv+l0FBzrP3gONQd35Zij7Xi3yybP4xJS2SsuVemqWZqEfMSL/ytb0cKfVVoznAkJ6H 6b1pCDZbYxCxdjiYNpLXbIN2TgLANSgx3lD+4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727325694; x=1727930494; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=/IK77nxbBZEPITpwoYAt/gwthd7nkAtPQWQqMMDw4Ls=; b=sKQs12tLkQFj886zHLjnTx7Dp4LJ7kU0xgzTjKPE+Mdyt4f/2UrVipiQD67d2HVbdR +BasxYORUyPbqqtKiijoYfuKzim8khZxQXg0Cnyn2zwNfXs+ZaNp5+dZGpfRnmHi2omF in8H9nqt+fpfWfKq2607GVyJIHlWTRKRwJMM/KzHE+i+RR5ySOXusIuZBY/9tgFgUu57 6mMViOvsEW44oTppHnMdj43k9VJcuxJSClIDAxeU3/L1Wvd2MW7i4Y4jh+sHJmBrmr21 dOZ3U9KaiJveAq8h2zEMRj5hSkjn7NOaC1++ExzjFiRladEMrBdyI+Ulgzg9SD4e1/ca BGFQ== X-Forwarded-Encrypted: i=1; AJvYcCWtiVpv4zvbw3wRKQm970j6WXzFASoWYC4PO4Q/uLV+zKVi2ejolfBiMr+Kkz/AXkUolEyExxovwcVK6Lg=@vger.kernel.org X-Gm-Message-State: AOJu0Yw0fR1/77+oGNzV2XIbMNwXU455mxYjvVTeEh+hY1V7EbVi4IRb jQq41l5wgJyACp8QNQERiIKSB7gRmO5xodZYUWGfKqXq6AVjufmR0NRzSV3Jiw== X-Google-Smtp-Source: AGHT+IEOD9BvUk8bvWmM8arHd+awbM4tS4muPPp5om+HbilxjplSMNBHUU3yJEROXfLfGcQzr2phbw== X-Received: by 2002:a05:6a00:8a81:b0:717:9754:4ade with SMTP id d2e1a72fcca58-71b0ac43ebamr4852805b3a.22.1727325693745; Wed, 25 Sep 2024 21:41:33 -0700 (PDT) Received: from google.com ([2401:fa00:8f:203:1560:84f:e0c8:d5d6]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-71afc9c6b96sm3476773b3a.191.2024.09.25.21.41.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2024 21:41:33 -0700 (PDT) Date: Thu, 26 Sep 2024 13:41:29 +0900 From: Sergey Senozhatsky To: Pankaj Raghav Cc: minchan@kernel.org, senozhatsky@chromium.org, linux-kernel@vger.kernel.org, axboe@kernel.dk, p.raghav@samsung.com, linux-block@vger.kernel.org, gost.dev@samsung.com Subject: Re: [PATCH 0/5] Improve zram writeback performance Message-ID: <20240926044129.GE11458@google.com> References: <20230911133430.1824564-1-kernel@pankajraghav.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: <20230911133430.1824564-1-kernel@pankajraghav.com> On (23/09/11 15:34), Pankaj Raghav wrote: > Batching reduces the time of writeback of 4G data to a nvme backing device > from 68 secs to 15 secs (more than **4x improvement**). I don't think anyone does that on practice. Excessive writeback wears out flash storage, so on practice no one writebacks gigabytes of data all at once, but instead people put daily writeback limits and try to be flash storage "friendly", which is especially important if your device has to a lifespan of 7 or 10 years. IOW usually writeback is put under such constraints that writeback speed is hardly noticeable. So I'm not sure that the complexity that this patch introduces is justified, to be honest.