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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 BDB0CC3DA60 for ; Wed, 17 Jul 2024 18:25:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TVRW8hLHIUSZNhVfLPVIOXLlJElKjBJKeg9q2jucIOk=; b=ILoP3pWFID6+Q2pNtUN1SvbXse GrhZYLULLGLtbNm/rITYuJZokiDz1Bt7PbAZMZ1ix4ohO/x5KlgjgRtVPrVqnjm24NKOmeHFCXSCr RsaQPAy7p2ZVj/yBuQc2h7tVzQPm6hz83dRl04LI/vSzrI1ZH7c0i3CO7DdDSXr8WRDPz5ue2K4Ku ML1NDbuelnPkXN9P46vmOq59jkGGlmfgw9Ty0cBRnzrXdV4qnkbsW8/KvQvC+sj4MocIOCuPVDu3W xJ0YvaQ+VuKIpAfKVCA/b2koDueFWfedw7y8HGgFzqfqg/9mxL3Lv79UuSG5mWxb2I+uTwi/OjgTz GvPquy9A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sU9Ks-0000000Ec9I-2OMp; Wed, 17 Jul 2024 18:25:06 +0000 Received: from mail-pf1-x433.google.com ([2607:f8b0:4864:20::433]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sU9KX-0000000Ec1m-2T0i; Wed, 17 Jul 2024 18:24:47 +0000 Received: by mail-pf1-x433.google.com with SMTP id d2e1a72fcca58-70b0e9ee7bcso5373602b3a.1; Wed, 17 Jul 2024 11:24:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1721240684; x=1721845484; darn=lists.infradead.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=TVRW8hLHIUSZNhVfLPVIOXLlJElKjBJKeg9q2jucIOk=; b=dcMNde86RSOKQ3ra3/87zWJHEk+XySccFzlIljQH24PrTQR8ooRPO81iD1Wh27bZS0 +1LSFt78h1NzGuHl6Z09rWnKBamzYUKJwK3BxQtoEdv4usyNoKSqpgwekf0etPrpz7iz u5MaUun8xa8rsxqutNlH3t6Ow1yPdnWXIjes2iR43VXlMabGA85881CNKghSe9OGZFJL RFx25r1WI3jFEzPQxB5kkQyjJ+nNJZqdyg86w51ZVk7tKX1whxkpKfy34aCyQLZXfSAQ PMgJDVJhPcEhJSbNcCkB1wMaJezpyHopYoEaWrB/wdQ9Ap7y1kugnKAzZc3bjH2HR7b4 R8mA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1721240684; x=1721845484; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=TVRW8hLHIUSZNhVfLPVIOXLlJElKjBJKeg9q2jucIOk=; b=p8qZMHWPzZsPfpLxVHjDTVdOM1ksSY+KDC49FxizPCkozXNsSamq9WB4vmUEg+1M3h m03hCcGKWWW/s+jOZATIMgjIJZcYUwOxvR5a5s8O+gaVO6NbP6WgXleqC0BrqeEIEBGo acOHrr9Cyi1oE9jAKH/xSxrab3Q4e17hNDHkVXWBGphwSR1CYdFwqDwI4gsikTpvx2o2 sTDt1d0kH3OZ0M0roisPYSP1maXdzKZy1lA4TstOuGBxZih/WYdBneZ16U6PF5YOX+IE 3aQIBvwWY+QHugJ9YwFaaGQbNcnsqOA+PWi+QQAmb8BxorbLIT/+A/6WvWYN0i04ntwZ O46A== X-Forwarded-Encrypted: i=1; AJvYcCVbvFM3RvvgNL0EaedMIr7xM1LpVmI1zjre/nzfaAU4KL5ZEkMYR2DyA34oV9lB1Zi61C5WLaFF1Aj6MSGRScVUjT1EcXb9LkbM1dzlZJca+Hs0dHmrLnT/1HDK1JFyZHZX+xu9rX+O4IcLa2RJTiDOUXu3Aa+bHXg= X-Gm-Message-State: AOJu0Yxlz1YcA1o9GOZ/GsZJsHR5BmUfU9MjK9afgRcdFd2Sduubc97z WYSzlLMv7Tv6xo7/JqPvBqK6u++8XgBp2M9A23l26yZhtCp/Y+MD X-Google-Smtp-Source: AGHT+IG+8XAut5x9RnVX0256xGnt+rKtGG2XFJero3WSej4KWrPLZ7hzVXL3loyY3SJ2Mysy4szevA== X-Received: by 2002:a05:6a00:2d83:b0:706:381e:318c with SMTP id d2e1a72fcca58-70ce4e8d2e5mr2750414b3a.7.1721240684126; Wed, 17 Jul 2024 11:24:44 -0700 (PDT) Received: from localhost (dhcp-141-239-149-160.hawaiiantel.net. [141.239.149.160]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-70b7ecd2820sm8436751b3a.212.2024.07.17.11.24.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jul 2024 11:24:43 -0700 (PDT) Date: Wed, 17 Jul 2024 08:24:42 -1000 From: "tj@kernel.org" To: Waiman Long Cc: Boy Wu =?utf-8?B?KOWQs+WLg+iqvCk=?= , "boris@bur.io" , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "cgroups@vger.kernel.org" , "linux-mediatek@lists.infradead.org" , "axboe@kernel.dk" , Iverlin Wang =?utf-8?B?KOeOi+iLs+mclik=?= , "josef@toxicpanda.com" , "linux-arm-kernel@lists.infradead.org" , "matthias.bgg@gmail.com" , "angelogioacchino.delregno@collabora.com" Subject: Re: [PATCH v3] blk-cgroup: Replace u64 sync with spinlock for iostat update Message-ID: References: <20240716075206.23121-1-boy.wu@mediatek.com> <5560c690cc6de67139a9b2e45c7a11938b70fc58.camel@mediatek.com> <1b19b68adb34410bf6dc8fd3f50e4b82c1a014e4.camel@mediatek.com> <134fc34c-10b8-4d00-aaca-8285efce9899@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <134fc34c-10b8-4d00-aaca-8285efce9899@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240717_112445_650316_AA8CA4A6 X-CRM114-Status: UNSURE ( 9.25 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hello, On Wed, Jul 17, 2024 at 02:18:39PM -0400, Waiman Long wrote: > Well, it can be confusing whether we are dealing with blkg->iostat or > blkg->iostat_cpu. In many cases, we are dealing with iostat_cpu instead of > iostat like __blkcg_rstat_flush() and blkg_clear_stat(). So we can't > eliminate the use of u64_stats_update_begin_irqsave() in those cases. I mean, we need to distinguish them. For 32bits, blkg->iostat has multiple updaters, so we can't use u64_sync; however, blkg->iostat_cpu has only one updater (except blkg_clear_stat() which I don't think we need to worry too much about), so u64_sync is fine. Thanks. -- tejun