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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2070C433EF for ; Sat, 5 Mar 2022 00:03:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230143AbiCEAEe (ORCPT ); Fri, 4 Mar 2022 19:04:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229521AbiCEAEe (ORCPT ); Fri, 4 Mar 2022 19:04:34 -0500 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4121D207A0A; Fri, 4 Mar 2022 16:03:45 -0800 (PST) X-UUID: d4708299e3234759b8b7d1d628fb891a-20220305 X-UUID: d4708299e3234759b8b7d1d628fb891a-20220305 Received: from mtkexhb01.mediatek.inc [(172.21.101.102)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 974430699; Sat, 05 Mar 2022 08:03:38 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.15; Sat, 5 Mar 2022 08:03:37 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sat, 5 Mar 2022 08:03:37 +0800 From: Miles Chen To: CC: , , , , , , , Subject: Re: [PATCH] iommu/iova: Improve 32-bit free space estimate Date: Sat, 5 Mar 2022 08:03:37 +0800 Message-ID: <20220305000337.24995-1-miles.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <77b0c978-7caa-c333-6015-1d784b5daf3f@arm.com> References: <77b0c978-7caa-c333-6015-1d784b5daf3f@arm.com> MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Joerg, Robin, > Applied without stable tag for now. If needed, please consider > re-sending it for stable when this patch is merged upstream. > Yeah, having figured out the history, I ended up with the opinion that > it was a missed corner-case optimisation opportunity, rather than an > actual error with respect to intent or implementation, so I > intentionally left that out. Plus figuring out an exact Fixes tag might > be tricky - as above I reckon it probably only started to become > significant somwehere around 5.11 or so. > > All of these various levels of retry mechanisms are only a best-effort > thing, and ultimately if you're making large allocations from a small > space there are always going to be *some* circumstances that still > manage to defeat them. Over time, we've made them try harder, but that > fact that we haven't yet made them try hard enough to work well for a > particular use-case does not constitute a bug. However as Joerg says, > anyone's welcome to make a case to Greg to backport a mainline commit if > it's a low-risk change with significant benefit to real-world stable > kernel users. Got it, thank you. We will try to push to the android LTS trees we need. Thanks, Miles > > Thanks all! > > Robin. 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 smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 19C2CC433EF for ; Sat, 5 Mar 2022 00:03:53 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id A7B70408CD; Sat, 5 Mar 2022 00:03:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fthuqr0vE_62; Sat, 5 Mar 2022 00:03:52 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 8EB99408D0; Sat, 5 Mar 2022 00:03:52 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 70F9DC0012; Sat, 5 Mar 2022 00:03:52 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id C7D57C000B for ; Sat, 5 Mar 2022 00:03:50 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id AC1A783E83 for ; Sat, 5 Mar 2022 00:03:50 +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 PFLWg0Q8HOEE for ; Sat, 5 Mar 2022 00:03:46 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by smtp1.osuosl.org (Postfix) with ESMTPS id CD1F783E80 for ; Sat, 5 Mar 2022 00:03:45 +0000 (UTC) X-UUID: d4708299e3234759b8b7d1d628fb891a-20220305 X-UUID: d4708299e3234759b8b7d1d628fb891a-20220305 Received: from mtkexhb01.mediatek.inc [(172.21.101.102)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 974430699; Sat, 05 Mar 2022 08:03:38 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.15; Sat, 5 Mar 2022 08:03:37 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sat, 5 Mar 2022 08:03:37 +0800 To: Subject: Re: [PATCH] iommu/iova: Improve 32-bit free space estimate Date: Sat, 5 Mar 2022 08:03:37 +0800 Message-ID: <20220305000337.24995-1-miles.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <77b0c978-7caa-c333-6015-1d784b5daf3f@arm.com> References: <77b0c978-7caa-c333-6015-1d784b5daf3f@arm.com> MIME-Version: 1.0 X-MTK: N Cc: wsd_upstream@mediatek.com, iommu@lists.linux-foundation.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, miles.chen@mediatek.com, yf.wang@mediatek.com, will@kernel.org 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: , From: Miles Chen via iommu Reply-To: Miles Chen Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Joerg, Robin, > Applied without stable tag for now. If needed, please consider > re-sending it for stable when this patch is merged upstream. > Yeah, having figured out the history, I ended up with the opinion that > it was a missed corner-case optimisation opportunity, rather than an > actual error with respect to intent or implementation, so I > intentionally left that out. Plus figuring out an exact Fixes tag might > be tricky - as above I reckon it probably only started to become > significant somwehere around 5.11 or so. > > All of these various levels of retry mechanisms are only a best-effort > thing, and ultimately if you're making large allocations from a small > space there are always going to be *some* circumstances that still > manage to defeat them. Over time, we've made them try harder, but that > fact that we haven't yet made them try hard enough to work well for a > particular use-case does not constitute a bug. However as Joerg says, > anyone's welcome to make a case to Greg to backport a mainline commit if > it's a low-risk change with significant benefit to real-world stable > kernel users. Got it, thank you. We will try to push to the android LTS trees we need. Thanks, Miles > > Thanks all! > > Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu