From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=113.46.200.224 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793170236; b=to966a40Rzjb2fTdlCySH0m+nbpZLr3gvqsw/3HhqWvSLrN2kf9TEx2JQUqCkT64cs2f 8JHm6PIt5Tu+TEidG5I+wkavc/mXFnjXFIx3TENUOwZYD7JItk38cazfLAHB5UA5IYagC yFr/kB87B3cUSUxLMQvDJXBLTzTkGSOM3eR6tUg42rK0zWlicp5mgAKOAVkN4t3uuOMXj /Zh7DlHc8bY2y64fI89QGJd1A8Hjdl3yy8il9Hi4bqG/J7OQY8UcbrfI35dZFy14yHcgF P6+er+ry7RyttXJvV2OuDb1OZnFVySp1F0+F98WS0SGhEhGUakuedgVcQl7PUT/81+g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793170236; h=DMARC-Filter:dkim-signature:Received:Received:Received:Message-ID: Date:MIME-Version:User-Agent:Subject:To:References:From:In-Reply-To: Content-Type:Content-Transfer-Encoding:X-Originating-IP: X-ClientProxiedBy; bh=MM4e7fqDmtE4Y1ZW9vkBOxUF+4WU0wru0ULzuQOF7XA=; b=0VixCM6zljjygfFagl6nCDzxsJx1coumtrvDz3mE5Pi4orEeeFCZlfBBiqDXxgT1S4Xc KNbnISF4pOOjfcS5Kkd1xCqzyw7N6CcOktlqWUzGxq2KB/x0BGALpzvBK1uzeYEHW5r58 fNvzGBR0ioSGgIz3bVQsaccc2UnGHTJ2oP/ZZ124xyiaIH0McGJZBrI6tOjDW9EmPu8Lh +SJ/SJyNeRBKQN3jO0xp0shhFBa6Xkmc0XHIoC8Drd7eN+PgbbyDOsrUntKOivdP0Gxd7 SiUMi5EKOITE159P9VO0dKrvIiRpwBVA5+EtYp0C6UhcPGZp+qlP/zNUbUPkOZQ8Tkg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass header.d=huawei.com header.i=@huawei.com header.a=rsa-sha256 header.s=dkim header.b=kDYCJR6S; arc=none smtp.remote-ip=113.46.200.224 Received: from canpmsgout09.his.huawei.com (canpmsgout09.his.huawei.com [113.46.200.224]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9DB13606A31A; Wed, 28 Oct 2026 06:50:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9DB13606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=huawei.com header.i=@huawei.com header.a=rsa-sha256 header.s=dkim header.b=kDYCJR6S dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=MM4e7fqDmtE4Y1ZW9vkBOxUF+4WU0wru0ULzuQOF7XA=; b=kDYCJR6SJ82tPv7VlCiiurY6K2bKbbvDJxj3cmhJNiV6IeumEI1K1Ib+EOGfAF0FExlMWgzAu 0VU372aPc4j52tFDFJU/YVCKIXA7Ib+XrObEW0jN50KdQLSSeIXeOxJiUQLp1wLBLvNsXAuLTK4 ibWmxgHJEB8QLqv5F/24Q3s= Received: from mail.maildlp.com (unknown [172.19.163.15]) by canpmsgout09.his.huawei.com (SkyGuard) with ESMTPS id 4jDyfl5V83z1cyqb; Wed, 28 Oct 2026 14:50:23 +0800 (CST) Received: from kwepemk200008.china.huawei.com (unknown [7.202.194.74]) by mail.maildlp.com (Postfix) with ESMTPS id 71B9340586; Wed, 28 Oct 2026 14:50:30 +0800 (CST) Received: from [10.67.110.68] (10.67.110.68) by kwepemk200008.china.huawei.com (7.202.194.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.45; Wed, 28 Oct 2026 14:50:29 +0800 Message-ID: Date: Wed, 28 Oct 2026 14:50:29 +0800 X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/7] arm_mpam: Add L2 cache monitors To: Ben Horgan , , , , , , , , , , , , , , , , References: <20261022084821.4014873-1-ruanjinjie@huawei.com> From: Jinjie Ruan In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To kwepemk200008.china.huawei.com (7.202.194.74) 在 2026/10/26 19:46, Ben Horgan 写道: > Hi Jinjie, > > On 22/10/2026 09:48, Jinjie Ruan wrote: >> MPAM resource monitors hang off a partitionable resource in an MSC, not >> off a particular cache level. resctrl only knows about the L3 scope, so >> the L2 cache monitors that MPAM platforms implement are discovered by >> the driver but never show up in resctrl. > > Yes, it would be good to add support for more monitoring scopes. This is not just relevant for MPAM. > RISC-V can also have monitors at many places in the system and we should coordinate so we have a > uniform solution across architectures. Hi Ben, Agree, we should take other emerging architectures such as RISC-V into account, design a more extensible solution. > >> >> An L2 MSC has the same CSU and MBWU counters as an L3 MSC; the cache >> level comes from the ACPI MPAM table's cache locator. So this is mostly >> a resctrl scope problem, not a hardware one. >> >> Extend resctrl's monitor scope to L2: register the L2 occupancy and >> bandwidth events against the L2 resource, pick the L2 classes for them, >> and borrow a CSU/MBWU monitor for the duration of a read. With CDP the > > Borrowing an MBWU monitor doesn't sound right. The MBWU monitor needs to be configured while the > traffic is happening so that it can keep count of bytes. The CSU is different as it can measure the > occupancy without having to keep any state. Thank you very much, will drop this approach and try the compatible solution you suggested. > > Thanks, > > Ben > >> two PARTIDs need separate accumulating monitors, so the borrowed-monitor >> context becomes one monitor per PARTID. >> >> Patches: >> >> 1-2 Generalise the per-domain read path, add l2c_occupancy and >> mbm_core_bytes, update the documentation. >> >> 3 Split the borrowed-monitor context into data and code entries. >> >> 4 Do the CDP num_rmid halving for every mon_capable resource. >> >> 5-7 Pick the L2 classes, describe the events with the L2 resource, >> add the read paths. >> >> Tested on QEMU with an L2/L3/memory-controller MSC topology. The L2_MON >> files show up and are readable; l2c_occupancy reports the modelled >> occupancy, and mbm_core_bytes reports the modelled bandwidth. >> >> QEMU branch: https://github.com/ruanjinjie-eng/qemu/tree/mpam >> Test cases: https://github.com/ruanjinjie-eng/mpam_testcase >> >> Jinjie Ruan (7): >> fs/resctrl: Generalize __l3_mon_event_count for non-L3 resources >> fs/resctrl: Add the L2 monitor events >> arm_mpam: resctrl: Split monitor context for code/data >> arm_mpam: resctrl: Halve num_rmid for every mon_capable resource on >> CDP >> arm_mpam: resctrl: Describe the L2 monitor events with the L2 resource >> arm_mpam: resctrl: Pick L2 classes for the L2 monitor events >> arm_mpam: resctrl: Add the L2 monitor read paths >> >> Documentation/arch/arm64/mpam.rst | 23 +-- >> drivers/resctrl/mpam_resctrl.c | 236 +++++++++++++++++++++++------- >> fs/resctrl/monitor.c | 15 +- >> include/linux/resctrl_types.h | 13 +- >> 4 files changed, 222 insertions(+), 65 deletions(-) >> > -- Best regards, Jinjie