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 566C5C05027 for ; Mon, 23 Jan 2023 15:34:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232339AbjAWPeA (ORCPT ); Mon, 23 Jan 2023 10:34:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40344 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231724AbjAWPd6 (ORCPT ); Mon, 23 Jan 2023 10:33:58 -0500 Received: from mail-qk1-x732.google.com (mail-qk1-x732.google.com [IPv6:2607:f8b0:4864:20::732]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A14331A976 for ; Mon, 23 Jan 2023 07:33:57 -0800 (PST) Received: by mail-qk1-x732.google.com with SMTP id x26so6598749qkj.4 for ; Mon, 23 Jan 2023 07:33:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=ZXpxTVFDU/4N2fs9Sln594JhoesX+RwFbstr1NRuPCQ=; b=sbEaMWJdzLuzZJrqAulWCafZ/v25sU35s7p+XR5Q35lcuRy0qoeDMp3j0TV2kRvapg 8mtOxkm1MKMZKsljDphrdfLp84sAc7r3aBZmZwIhNQT5nKqZGHnKNRURsLc9wOnI1kss B8+EkojNTf6/t4sAnZf5RZbuv2VmfZSfNNA1yyKNTDrfELaNPTkXYadDkNwxDweTU0RM VIMegROguAsCWumyf6c9VDz6HsfhR3Yw4eArM3cdN//p9l49pt9CoxBRmAHl95AisQEu O93oyzOziZ/LUIvXnOTkgVrWZ7KuXBxwnWZsulYWmdsxJ0Vhwr6Kz1En4ZGltmba5jEK JD0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=ZXpxTVFDU/4N2fs9Sln594JhoesX+RwFbstr1NRuPCQ=; b=GO8CXdLH3vyvg6auIo/dOABkzWX6yuRpBiRBC7BS9UZB93uumzzm1yTkxdtbx2HoHm DZJ+oPcJIqy8Oz5nR4JuylTuHQ/zxhIMRGPeR2OmmnbATCWAoMCPh9jLH35IxnmGJdqB pBhP4M8INQAuQuCirsVt9rba/TBaf0wn1OJo+6x+p/z3hXKDsBtDOdiVJumQhUjd1C5E 0BTBven3YRwJJhf5bIIXEXbvmLYyqdX33HHtgGn4dBHC4uI9tzQKRl10LWMY5zIs0HCK ajIM49FpvpTv5iizckT/NE1QgtDCfD8pQ0l8EXQDcmqXuyqJY2p6GHTVSnGpWK31Tjtf rkGg== X-Gm-Message-State: AFqh2kpFF76t96wm2H6JKUel1GrKsKRAa91gJZNNHUTfxM6RLB6Xs2ZY PvpgsfzuyjpjsrOVjRX/DIpiozRvcfbJdkvcHTIHIQ== X-Google-Smtp-Source: AMrXdXtXGJ5Ng4fgxnumc+iIzYvH9ZJpIHxw75ljeHzRjPEolnQJvMLz84YDeOntNGJ8nbxQqaXvsrCkvQry4rYkGR0= X-Received: by 2002:a05:620a:31a4:b0:706:7050:fbdf with SMTP id bi36-20020a05620a31a400b007067050fbdfmr1553646qkb.380.1674488036671; Mon, 23 Jan 2023 07:33:56 -0800 (PST) MIME-Version: 1.0 References: <20230113175459.14825-1-james.morse@arm.com> <20230113175459.14825-10-james.morse@arm.com> In-Reply-To: <20230113175459.14825-10-james.morse@arm.com> From: Peter Newman Date: Mon, 23 Jan 2023 16:33:45 +0100 Message-ID: Subject: Re: [PATCH v2 09/18] x86/resctrl: Allow resctrl_arch_rmid_read() to sleep To: James Morse Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Fenghua Yu , Reinette Chatre , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Babu Moger , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, xingxin.hx@openanolis.org, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 13, 2023 at 6:56 PM James Morse wrote: > MPAM's cache occupancy counters can take a little while to settle once > the monitor has been configured. The maximum settling time is described > to the driver via a firmware table. The value could be large enough > that it makes sense to sleep. Would it be easier to return an error when reading the occupancy count too soon after configuration? On Intel it is already normal for counter reads to fail on newly-allocated RMIDs. -Peter