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=-11.9 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 6CC68C433E6 for ; Fri, 28 Aug 2020 07:31:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 241C92071B for ; Fri, 28 Aug 2020 07:31:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="HSADVyi2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728421AbgH1Hbd (ORCPT ); Fri, 28 Aug 2020 03:31:33 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:33356 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726500AbgH1Hbc (ORCPT ); Fri, 28 Aug 2020 03:31:32 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1598599891; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=ok6qYeTFJS9pQDEh8V4WjrEAxhk28wu/qsnprTATYWk=; b=HSADVyi2+kBvfDcsx0vQe5lXgJkXMMy8XLc1NiiarPRBeRNLAVNF+mZ2Rgx28ZbZBgs+x9Y8 QcYzZzFRV339mNWYNV23e5orLMuOu6xKyOulylV4da5/P8Zpn63Z8/tglNI5sbqQFByxhqHO FQ080uubj7HI/rh2WXWHdVT6aUg= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n06.prod.us-east-1.postgun.com with SMTP id 5f48b2c29db79768eb9b3363 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Fri, 28 Aug 2020 07:31:14 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 30885C43391; Fri, 28 Aug 2020 07:31:14 +0000 (UTC) Received: from [192.168.0.104] (unknown [103.248.210.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: vjitta) by smtp.codeaurora.org (Postfix) with ESMTPSA id A283CC433C6; Fri, 28 Aug 2020 07:31:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org A283CC433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=vjitta@codeaurora.org Subject: Re: [PATCH v2 1/2] iommu/iova: Retry from last rb tree node if iova search fails To: joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: vinmenon@codeaurora.org, kernel-team@android.com, robin.murphy@arm.com References: <1597927761-24441-1-git-send-email-vjitta@codeaurora.org> From: Vijayanand Jitta Message-ID: <782f5dae-4ebc-02c8-5c83-4f7efda65c9d@codeaurora.org> Date: Fri, 28 Aug 2020 13:01:03 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <1597927761-24441-1-git-send-email-vjitta@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/20/2020 6:19 PM, vjitta@codeaurora.org wrote: > From: Vijayanand Jitta > > When ever a new iova alloc request comes iova is always searched > from the cached node and the nodes which are previous to cached > node. So, even if there is free iova space available in the nodes > which are next to the cached node iova allocation can still fail > because of this approach. > > Consider the following sequence of iova alloc and frees on > 1GB of iova space > > 1) alloc - 500MB > 2) alloc - 12MB > 3) alloc - 499MB > 4) free - 12MB which was allocated in step 2 > 5) alloc - 13MB > > After the above sequence we will have 12MB of free iova space and > cached node will be pointing to the iova pfn of last alloc of 13MB > which will be the lowest iova pfn of that iova space. Now if we get an > alloc request of 2MB we just search from cached node and then look > for lower iova pfn's for free iova and as they aren't any, iova alloc > fails though there is 12MB of free iova space. > > To avoid such iova search failures do a retry from the last rb tree node > when iova search fails, this will search the entire tree and get an iova > if its available. > > Signed-off-by: Vijayanand Jitta > --- > drivers/iommu/iova.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c > index 49fc01f..4e77116 100644 > --- a/drivers/iommu/iova.c > +++ b/drivers/iommu/iova.c > @@ -184,8 +184,9 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, > struct rb_node *curr, *prev; > struct iova *curr_iova; > unsigned long flags; > - unsigned long new_pfn; > + unsigned long new_pfn, low_pfn_new; > unsigned long align_mask = ~0UL; > + unsigned long high_pfn = limit_pfn, low_pfn = iovad->start_pfn; > > if (size_aligned) > align_mask <<= fls_long(size - 1); > @@ -198,15 +199,25 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad, > > curr = __get_cached_rbnode(iovad, limit_pfn); > curr_iova = rb_entry(curr, struct iova, node); > + low_pfn_new = curr_iova->pfn_hi + 1; > + > +retry: > do { > - limit_pfn = min(limit_pfn, curr_iova->pfn_lo); > - new_pfn = (limit_pfn - size) & align_mask; > + high_pfn = min(high_pfn, curr_iova->pfn_lo); > + new_pfn = (high_pfn - size) & align_mask; > prev = curr; > curr = rb_prev(curr); > curr_iova = rb_entry(curr, struct iova, node); > - } while (curr && new_pfn <= curr_iova->pfn_hi); > - > - if (limit_pfn < size || new_pfn < iovad->start_pfn) { > + } while (curr && new_pfn <= curr_iova->pfn_hi && new_pfn >= low_pfn); > + > + if (high_pfn < size || new_pfn < low_pfn) { > + if (low_pfn == iovad->start_pfn && low_pfn_new < limit_pfn) { > + high_pfn = limit_pfn; > + low_pfn = low_pfn_new; > + curr = &iovad->anchor.node; > + curr_iova = rb_entry(curr, struct iova, node); > + goto retry; > + } > iovad->max32_alloc_size = size; > goto iova32_full; > } > ping ? Thanks, Vijay -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation