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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 5FAF8C433B4 for ; Tue, 13 Apr 2021 09:36:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 40BAF613B6 for ; Tue, 13 Apr 2021 09:36:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229446AbhDMJhJ (ORCPT ); Tue, 13 Apr 2021 05:37:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:54219 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229573AbhDMJhJ (ORCPT ); Tue, 13 Apr 2021 05:37:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1618306609; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xZtiYxndyvrgRiioNGZHGj1zKctLULruJBTNpZ12M30=; b=Bu6BD9vTTznlSeYfMJX1RDAZEWP7ZDGx5RFdGAvXJSk2N12XZyHh8qXO2JzsvaaOId7/Wu tnDaw1qPQkNgfVFEjwtzD4N0Vu3L2pAIgCEt2fSGL4MFy7CHYldvvzDdWRCg+OkooCtY3S LGIQzysVt6czqvfQWlMXOtYqcVlI/Bk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-228-cHL0jHROMuCFWGrL6Pfuhg-1; Tue, 13 Apr 2021 05:36:45 -0400 X-MC-Unique: cHL0jHROMuCFWGrL6Pfuhg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A593D88127C; Tue, 13 Apr 2021 09:36:44 +0000 (UTC) Received: from T590 (ovpn-12-66.pek2.redhat.com [10.72.12.66]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 05D916F98A; Tue, 13 Apr 2021 09:36:30 +0000 (UTC) Date: Tue, 13 Apr 2021 17:36:26 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , linux-block@vger.kernel.org, Jeffle Xu , Mike Snitzer , dm-devel@redhat.com, Hannes Reinecke Subject: Re: [PATCH V5 05/12] block: add new field into 'struct bvec_iter' Message-ID: References: <20210401021927.343727-1-ming.lei@redhat.com> <20210401021927.343727-6-ming.lei@redhat.com> <20210412092653.GA972763@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210412092653.GA972763@infradead.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Apr 12, 2021 at 10:26:53AM +0100, Christoph Hellwig wrote: > I don't like where this is going. > > I think the model of storing the polling cookie in the bio is useful, > but: > > (1) I think having this in the iter is a mess. Can you measure if > just marking bvec_iter __packed will generate much worse code > at all anymore? If not we can just move this into the bio Just test with packed 'struct bvec_iter' by running io_uring/libaio over nvme/null_blk with different bs size, not see obvious difference compared with unpacked bvec_iter. So will switch to packed bvec_iter in next version. > If it really generates much worse code I think you need to pick > a different name as as that i really confusing vs the bio field > of the same name that is used entirely differenly. Similarly > the bio_get_private_data and bio_set_private_data helpers are > entirely misnamed, as the names suggest they deal with the > bi_private field in struct bio. I actually suspect not having > these helpers would be much preferable OK, how about naming it as .bi_poll_data? Thanks, Ming