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=-7.2 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 09F26C433FE for ; Fri, 4 Dec 2020 11:52:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC55522AAF for ; Fri, 4 Dec 2020 11:52:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729404AbgLDLwM (ORCPT ); Fri, 4 Dec 2020 06:52:12 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:21667 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725999AbgLDLwM (ORCPT ); Fri, 4 Dec 2020 06:52:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607082646; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GzGm9FLoIdgD7158tKHO7AwFPJgMNOe/jG6ldiSBZjg=; b=Er3m+06habVTsmjtOUIl6IdGMr/oflRFfOJwE/H/i1+OT1UzrZdWWrtqEdR/QcPbt2kMzn IpHayRYcybk47S7xQ7g3ulS4cuoYTguyJOPnop9Z4hkz1y8b4ZfJamA4vqNgaEGJac1pe2 /EeisqT5+k0E0yJgpKnUr5MuH89/q8U= 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-125-p8Q3snq-Oo-ITMhIPmR8nQ-1; Fri, 04 Dec 2020 06:50:42 -0500 X-MC-Unique: p8Q3snq-Oo-ITMhIPmR8nQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3059E612A3; Fri, 4 Dec 2020 11:50:40 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-116-67.rdu2.redhat.com [10.10.116.67]) by smtp.corp.redhat.com (Postfix) with ESMTP id BF9C65D6A1; Fri, 4 Dec 2020 11:50:37 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <160596801020.154728.15935034745159191564.stgit@warthog.procyon.org.uk> <20201203064536.GE27350@xsang-OptiPlex-9020> To: Linus Torvalds Cc: dhowells@redhat.com, kernel test robot , lkp@lists.01.org, kernel test robot , "Huang, Ying" , Feng Tang , zhengjun.xing@intel.com, Pavel Begunkov , Matthew Wilcox , Jens Axboe , Alexander Viro , linux-fsdevel , linux-block , Linux Kernel Mailing List Subject: Re: [iov_iter] 9bd0e337c6: will-it-scale.per_process_ops -4.8% regression MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <98236.1607082636.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Fri, 04 Dec 2020 11:50:36 +0000 Message-ID: <98237.1607082636@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds wrote: > > FYI, we noticed a -4.8% regression of will-it-scale.per_process_ops du= e to commit: > = > Ok, I guess that's bigger than expected, = Note that it appears to be testing just the first patch and not the whole series: | commit: 9bd0e337c633aed3e8ec3c7397b7ae0b8436f163 ("[PATCH 01/29] iov_ite= r: Switch to using a table of operations") that just adds an indirection table without taking away any of the conditi= onal branching. It seems quite likely, though, that even if you add all the ot= her patches, you won't get back enough to make it worth it. David