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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98D33C433EF for ; Wed, 20 Oct 2021 17:29:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E24F60F9F for ; Wed, 20 Oct 2021 17:29:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230385AbhJTRbe (ORCPT ); Wed, 20 Oct 2021 13:31:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36918 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230383AbhJTRb0 (ORCPT ); Wed, 20 Oct 2021 13:31:26 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37632C06161C for ; Wed, 20 Oct 2021 10:29:12 -0700 (PDT) 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=5EkxZf2eMV9JL5MvIdT/IOmsCeNDQTUDESVj/mqBxWY=; b=JxVEBuQq3GSo/Sv7p+9WRW/gDR wt/7aMvx/kzcQEF7wvjDOVt9mGPElRmL1injMvNKxOnwyP9NgiBqflGZ+vQrwNdF222xOtYng8Wx4 xyL0bQ6pR5wphe4sovzGereXJ5OuXLCyfQKL2J4CJnHsbj6Fi1rSEfFb6RcqNiRWIQjj0BMU0bSSg jeSMrZ4N+7FOnCh/R5av4nsiXhl0PkyqSEVTnLBqVxbzJ1RwOg1IjIiy6BnT0gZoCemeZDgbrAvME oPklq1VwdvCSZSzWgzC/p/guw+QZuD+jZiY/uyHVRjvWzHnXDbPUbxqbFfh4IOq/kjbeVvJO3Uu5y Woc9QJpg==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mdFOp-005K35-2p; Wed, 20 Oct 2021 17:29:11 +0000 Date: Wed, 20 Oct 2021 10:29:11 -0700 From: Christoph Hellwig To: Jens Axboe Cc: Christoph Hellwig , Pavel Begunkov , linux-block@vger.kernel.org Subject: Re: [PATCH 05/16] block: inline a part of bio_release_pages() Message-ID: References: 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 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Oct 20, 2021 at 08:15:25AM -0600, Jens Axboe wrote: > I just want to be very clear that neither mine nor Pavel's work is > trying to get into benchmarketing. There are very tangible performance > benefits, and they are backed up by code analysis and testing. That > said, the point is of course not to make this any harder to follow or > maintain, but we are doing suboptimal things in various places and those > should get cleaned up, particularly when they impact performance. Are > some a big eager? Perhaps, but let's not that that cloud the perception > of the effort as a whole. A lot of it seems generally useful. But optimizing for BIO_NO_PAGE_REF is really special. Besides a few in-kernel special cases this is all about the io_uring pre-registered buffers, which are very much a special case and not a normal workload at all. In this case it is just an extra conditional moved into a few callers so I think we're ok, but I'm really worried about optimizing this benchmark fast path over the code everyone actually uses.