From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFEFDC04EB8 for ; Thu, 6 Dec 2018 19:43:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8340C20868 for ; Thu, 6 Dec 2018 19:43:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="pihvYK5R" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8340C20868 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725921AbeLFTnC (ORCPT ); Thu, 6 Dec 2018 14:43:02 -0500 Received: from mail-it1-f194.google.com ([209.85.166.194]:38122 "EHLO mail-it1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725908AbeLFTnC (ORCPT ); Thu, 6 Dec 2018 14:43:02 -0500 Received: by mail-it1-f194.google.com with SMTP id h65so3397087ith.3 for ; Thu, 06 Dec 2018 11:43:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=5MUMEi7zu0YmJoCgXYMz6CuFfgMJhsSYdfj4OTTyE68=; b=pihvYK5RnBmvoMUliduZzkEf1wvO0vYP+LsTopm4sWhGQ83tour3iCs7SajecmzXdB iKUnEjymiqywl3PJbnH6G6+1vBs+BDu7nsogdNpz3msl6MkHetX+msJlfBaLT5aqKstp jA3QINLz2VMYtisASoQWFkxHUTK9RuyxzsHWVySU5UJeGM9eKrm1Y5+XyOvs3+zJdYDP +33j6jQt3iiaDtd3nhl8V40N1adCBBkgjAwYNwnjM7cTdaPEjayEApUayMkLYi3gkJz2 ZPKt6nELSRqkQHPc+jR2AnAQ1p8lL4+drbmmZfuiVlxscJDvwCCXUPBl7RG+b4Pv8b+g 9jdw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=5MUMEi7zu0YmJoCgXYMz6CuFfgMJhsSYdfj4OTTyE68=; b=n14lbG64sYu1D1AXP6e0VWLrjyf4t1U53/PWs2Qj2JsaVESJbXKqii4eeNgrjv4GAm FH7OBvJnH4NSLSlM1yVVOKcb3XGnQh94JEJK3hQd1STzJ0p6pQkZZUuC6KsmMdpNg3i7 7zf+HHp5rgCLJzAhHF4BGwnQoe2m4xIgEYfw0LJGrhm5u72zmpiiekLsuJFiCb+VwBsT ypQ5uzSN71KqqvN9cb18MGqymrKkREi8V/WJv7fT9Md7c0kiMETNc29VwjlkUZc5c2lJ XXgss6F3ICtsAaLQbQ8jenMHdnY5nweYA5JFSyiPDfiWqXfcIdHIRC/vGivqUE+v+0L7 PZMA== X-Gm-Message-State: AA+aEWYhN+2vMFxYanF5NNtYTYXIaHVfAmC/D6UaVNIeuyv5j2j6kNmr AlM7v3pAWbCCxrT9bikauK+oqA== X-Google-Smtp-Source: AFSGD/Xuf4ho9sR4vB1w/G5ruLXX0e6hUs3bptpyJzDX7VMrHBW0Soy8amjqb0tDZMMAyY7BVgSI2A== X-Received: by 2002:a24:af07:: with SMTP id t7mr17134057ite.168.1544125380694; Thu, 06 Dec 2018 11:43:00 -0800 (PST) Received: from [192.168.1.56] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id g10sm478496iop.25.2018.12.06.11.42.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Dec 2018 11:42:59 -0800 (PST) Subject: Re: [PATCH 08/26] aio: don't zero entire aio_kiocb aio_get_req() To: Jeff Moyer Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, hch@lst.de References: <20181204233729.26776-1-axboe@kernel.dk> <20181204233729.26776-9-axboe@kernel.dk> <99b52953-091d-007c-43aa-41198b0ed747@kernel.dk> From: Jens Axboe Message-ID: <72e91bed-b135-2d6a-c26a-bf65afed990c@kernel.dk> Date: Thu, 6 Dec 2018 12:42:58 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 12/6/18 12:38 PM, Jeff Moyer wrote: > Jens Axboe writes: > >> On 12/6/18 12:27 PM, Jeff Moyer wrote: >>> Jens Axboe writes: >>> >>>> It's 192 bytes, fairly substantial. Most items don't need to be cleared, >>>> especially not upfront. Clear the ones we do need to clear, and leave >>>> the other ones for setup when the iocb is prepared and submitted. >>> >>> What performance gains do you see from this? >> >> Before this, I had 1% in memset doing high IOPS. With it, that's gone. >> 1% is a lot, when you have just one thread doing everything from submission >> to completion. > > I'm used to customers complaining about fractions of a percent, so I get > it. :-) I just wanted to know we had some measurable impact, as I've > seen bugs crop up from code like this in the past. Oh for sure, I wouldn't do it if there wasn't a noticeable gain from this! -- Jens Axboe