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 smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 24CDAC433FE for ; Tue, 31 May 2022 19:48:34 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id B283283FED; Tue, 31 May 2022 19:48:34 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id t77bo1qe16hc; Tue, 31 May 2022 19:48:33 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp1.osuosl.org (Postfix) with ESMTPS id 8297A83F63; Tue, 31 May 2022 19:48:33 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 5B7A2C0032; Tue, 31 May 2022 19:48:33 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 17ACFC002D for ; Tue, 31 May 2022 19:48:32 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id F1B7E6129A for ; Tue, 31 May 2022 19:48:31 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6mrFZUFpoYJE for ; Tue, 31 May 2022 19:48:31 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp3.osuosl.org (Postfix) with ESMTP id 2EEE161296 for ; Tue, 31 May 2022 19:48:31 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4283523A; Tue, 31 May 2022 12:48:30 -0700 (PDT) Received: from [10.57.81.38] (unknown [10.57.81.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B791E3F766; Tue, 31 May 2022 12:48:28 -0700 (PDT) Message-ID: Date: Tue, 31 May 2022 20:48:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH 04/10] dmapool: improve accuracy of debug statistics Content-Language: en-GB To: Tony Battersby , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <9b08ab7c-b80b-527d-9adf-7716b0868fbc@cybernetics.com> From: Robin Murphy In-Reply-To: Cc: Tony Lindgren , Andy Shevchenko , Matthew Wilcox , iommu@lists.linux-foundation.org, Keith Busch , kernel-team@fb.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2022-05-31 19:17, Tony Battersby wrote: > The "total number of blocks in pool" debug statistic currently does not > take the boundary value into account, so it diverges from the "total > number of blocks in use" statistic when a boundary is in effect. Add a > calculation for the number of blocks per allocation that takes the > boundary into account, and use it to replace the inaccurate calculation. > > This depends on the patch "dmapool: fix boundary comparison" for the > calculated blks_per_alloc value to be correct. > > Signed-off-by: Tony Battersby > --- > mm/dmapool.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/dmapool.c b/mm/dmapool.c > index 782143144a32..9e30f4425dea 100644 > --- a/mm/dmapool.c > +++ b/mm/dmapool.c > @@ -47,6 +47,7 @@ struct dma_pool { /* the pool */ > struct device *dev; > unsigned int allocation; > unsigned int boundary; > + unsigned int blks_per_alloc; > char name[32]; > struct list_head pools; > }; > @@ -92,8 +93,7 @@ static ssize_t pools_show(struct device *dev, struct device_attribute *attr, cha > /* per-pool info, no real statistics yet */ > temp = scnprintf(next, size, "%-16s %4zu %4zu %4u %2u\n", Nit: if we're tinkering with this, it's probably worth updating the whole function to use sysfs_emit{_at}(). > 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. Thanks, Robin. > > INIT_LIST_HEAD(&retval->pools); > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu