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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D384DC433F5 for ; Tue, 31 May 2022 19:52:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6AC7F6B0071; Tue, 31 May 2022 15:52:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6583A6B0073; Tue, 31 May 2022 15:52:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 520C76B0074; Tue, 31 May 2022 15:52:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 444266B0071 for ; Tue, 31 May 2022 15:52:43 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id E902112052B for ; Tue, 31 May 2022 19:52:42 +0000 (UTC) X-FDA: 79527085806.10.114D7F6 Received: from mail.cybernetics.com (mail.cybernetics.com [173.71.130.66]) by imf12.hostedemail.com (Postfix) with ESMTP id 8D47840069 for ; Tue, 31 May 2022 19:52:01 +0000 (UTC) X-ASG-Debug-ID: 1654026760-1cf43917f334bc90001-v9ZeMO Received: from cybernetics.com ([10.10.4.126]) by mail.cybernetics.com with ESMTP id QMvSFwNwLMI2vW0s; Tue, 31 May 2022 15:52:40 -0400 (EDT) X-Barracuda-Envelope-From: tonyb@cybernetics.com X-ASG-Whitelist: Client DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=cybernetics.com; s=mail; bh=zaY0KN5bbdhdGj5w5iqbSpBFgDXMIwvTrwlB06Godyg=; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From:References:Cc:To: Content-Language:Subject:MIME-Version:Date:Message-ID; b=IFInqWoaVpE2F1jFz/+r jyb5wPZuz63wZQg6jpwm5m5ElcALvbK5NO5QskKNmwuWJqfKc7YaZ42NFF6+NjJ5DgR2mrihQ4ZoU x8Ap/beCyzlKBxutxj/P1Vc3ktqab1UlduPF13iLWKWhPHdW1PP3PM6YtKmCrknWqgNBRiomNQ= Received: from [10.157.2.224] (HELO [192.168.200.1]) by cybernetics.com (CommuniGate Pro SMTP 7.1.1) with ESMTPS id 11829739; Tue, 31 May 2022 15:52:40 -0400 Message-ID: Date: Tue, 31 May 2022 15:52:40 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH 04/10] dmapool: improve accuracy of debug statistics Content-Language: en-US X-ASG-Orig-Subj: Re: [PATCH 04/10] dmapool: improve accuracy of debug statistics To: Robin Murphy , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: iommu@lists.linux-foundation.org, kernel-team@fb.com, Matthew Wilcox , Keith Busch , Andy Shevchenko , Tony Lindgren References: <9b08ab7c-b80b-527d-9adf-7716b0868fbc@cybernetics.com> From: Tony Battersby In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Barracuda-Connect: UNKNOWN[10.10.4.126] X-Barracuda-Start-Time: 1654026760 X-Barracuda-URL: https://10.10.4.122:443/cgi-mod/mark.cgi X-Barracuda-BRTS-Status: 1 X-Virus-Scanned: by bsmtpd at cybernetics.com X-Barracuda-Scan-Msg-Size: 1028 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8D47840069 X-Stat-Signature: 3ddqm5mnyqydn93mp1i35i1awo5m7ak8 Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=cybernetics.com header.s=mail header.b=IFInqWoa; dmarc=pass (policy=none) header.from=cybernetics.com; spf=pass (imf12.hostedemail.com: domain of "btv1==1503f279fc1==tonyb@cybernetics.com" designates 173.71.130.66 as permitted sender) smtp.mailfrom="btv1==1503f279fc1==tonyb@cybernetics.com" X-HE-Tag: 1654026721-478530 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 5/31/22 15:48, Robin Murphy wrote: > On 2022-05-31 19:17, Tony Battersby wrote: > >> pool->name, blocks, >> - (size_t) pages * >> - (pool->allocation / pool->size), >> + (size_t) pages * pool->blks_per_alloc, >> pool->size, pages); >> size -= temp; >> next += temp; >> @@ -168,6 +168,9 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev, >> retval->size = size; >> retval->boundary = boundary; >> retval->allocation = allocation; >> + retval->blks_per_alloc = >> + (allocation / boundary) * (boundary / size) + >> + (allocation % boundary) / size; > Do we really need to store this? Sure, 4 divisions (which could possibly > be fewer given the constraints on boundary) isn't the absolute cheapest > calculation, but I still can't imagine anyone would be polling sysfs > stats hard enough to even notice. > The stored value is also used in patch #5, in more performance-critical code, although only when debug is enabled. Tony