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 03143CCFA13 for ; Mon, 10 Nov 2025 13:50:55 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:CC:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tTVZptE9yhavDPYFhKzpNou/6CcU7o9cuxLzEmT1XSo=; b=ei9mEcbsWYQn/JAn6NSJDAwE7J ImlVaj5pJY4bzAfgeSE8WTvYmzQxAlDegM4Vawr/ZGq7cp5v8rV9VnO/NIOAzVUJXcuH39klQtaLF Ax6yeMO92qUJ0ClGKGpN+PdmASXs0uIG/PZhLJa4lv7/urXYwHqGpSAHdEU5QdiqLFwqPnwmYkI18 zy9t16Cmk90cXYJZ5uvQQCbTyorfW5LfrLzqv+Q4A6x3D0hrp2OEuJhSAcrMXjl6Z3TtmnbY1Ahw7 rTHzWhVzdjdr217kU+gboqqdJrmggDrV/GUa2QgoWJe0HNhdXMZw9mT+24DniPrYm3A+QZcL0Z4l9 /o9dEq0w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vISIB-00000005XEH-0A3k; Mon, 10 Nov 2025 13:50:47 +0000 Received: from canpmsgout09.his.huawei.com ([113.46.200.224]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vISI7-00000005XCW-0YBp for linux-arm-kernel@lists.infradead.org; Mon, 10 Nov 2025 13:50:45 +0000 dkim-signature: v=1; a=rsa-sha256; d=h-partners.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=tTVZptE9yhavDPYFhKzpNou/6CcU7o9cuxLzEmT1XSo=; b=UD0fhW2SqX/JSAcOaD/yxVnfiTA5qPzfQCSMIKBD5kQ+/8y535cdK8FU+D6oTTQR7986lK/F4 glg5leKC1YVV7GuuX7ZnqNDQ04yxpOLe98GImTY3O2iRCtWyxGwTwQtQhT14zE5S6quiKbeS7Mk 8kTvaLMU37O54CGhjIWb51M= Received: from mail.maildlp.com (unknown [172.19.163.17]) by canpmsgout09.his.huawei.com (SkyGuard) with ESMTPS id 4d4rcB1Ddgz1cyPS; Mon, 10 Nov 2025 21:48:58 +0800 (CST) Received: from kwepemf100008.china.huawei.com (unknown [7.202.181.222]) by mail.maildlp.com (Postfix) with ESMTPS id DAC661A0188; Mon, 10 Nov 2025 21:50:36 +0800 (CST) Received: from [10.174.178.24] (10.174.178.24) by kwepemf100008.china.huawei.com (7.202.181.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 10 Nov 2025 21:50:34 +0800 Message-ID: <7df04942-5afa-604d-3573-ec54a2c89945@huawei.com> Date: Mon, 10 Nov 2025 21:50:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH 28/33] arm_mpam: Consider overflow in bandwidth counter state Content-Language: en-US To: Ben Horgan , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20251107123450.664001-1-ben.horgan@arm.com> <20251107123450.664001-29-ben.horgan@arm.com> From: Zeng Heng In-Reply-To: <20251107123450.664001-29-ben.horgan@arm.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.24] X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemf100008.china.huawei.com (7.202.181.222) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251110_055043_514661_75F01E10 X-CRM114-Status: GOOD ( 23.16 ) 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 On 2025/11/7 20:34, Ben Horgan wrote: > Use the overflow status bit to track overflow on each bandwidth counter > read and add the counter size to the correction when overflow is detected. > > This assumes that only a single overflow has occurred since the last read > of the counter. Overflow interrupts, on hardware that supports them could > be used to remove this limitation. > > Cc: Zeng Heng > Signed-off-by: Ben Horgan > --- > drivers/resctrl/mpam_devices.c | 24 ++++++++++++++++++++++-- > drivers/resctrl/mpam_internal.h | 3 ++- > 2 files changed, 24 insertions(+), 3 deletions(-) > > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > index 2d1cef824b8e..eea082dfcddc 100644 > --- a/drivers/resctrl/mpam_devices.c > +++ b/drivers/resctrl/mpam_devices.c > @@ -986,11 +986,18 @@ static void write_msmon_ctl_flt_vals(struct mon_read *m, u32 ctl_val, > } > } > > +static u64 mpam_msmon_overflow_val(enum mpam_device_features type) > +{ > + /* TODO: scaling, and long counters */ > + return BIT_ULL(hweight_long(MSMON___VALUE)); > +} > + > static void __ris_msmon_read(void *arg) > { > u64 now; > bool nrdy = false; > bool config_mismatch; > + bool overflow; > struct mon_read *m = arg; > struct mon_cfg *ctx = m->ctx; > struct mpam_msc_ris *ris = m->ris; > @@ -1012,13 +1019,20 @@ static void __ris_msmon_read(void *arg) > * This saves waiting for 'nrdy' on subsequent reads. > */ > read_msmon_ctl_flt_vals(m, &cur_ctl, &cur_flt); > + overflow = cur_ctl & MSMON_CFG_x_CTL_OFLOW_STATUS; > + > clean_msmon_ctl_val(&cur_ctl); > gen_msmon_ctl_flt_vals(m, &ctl_val, &flt_val); > config_mismatch = cur_flt != flt_val || > cur_ctl != (ctl_val | MSMON_CFG_x_CTL_EN); > > - if (config_mismatch) > + if (config_mismatch) { > write_msmon_ctl_flt_vals(m, ctl_val, flt_val); > + overflow = false; > + } else if (overflow) { > + mpam_write_monsel_reg(msc, CFG_MBWU_CTL, > + cur_ctl & ~MSMON_CFG_x_CTL_OFLOW_STATUS); > + } > > switch (m->type) { > case mpam_feat_msmon_csu: > @@ -1038,7 +1052,13 @@ static void __ris_msmon_read(void *arg) > > mbwu_state = &ris->mbwu_state[ctx->mon]; > > - /* Include bandwidth consumed before the last hardware reset */ > + if (overflow) > + mbwu_state->correction += mpam_msmon_overflow_val(m->type); > + > + /* > + * Include bandwidth consumed before the last hardware reset and > + * a counter size increment for each overflow. > + */ > now += mbwu_state->correction; > break; > default: > diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h > index 1f2b04b7703e..7c99d4f3dc9c 100644 > --- a/drivers/resctrl/mpam_internal.h > +++ b/drivers/resctrl/mpam_internal.h > @@ -209,7 +209,8 @@ struct msmon_mbwu_state { > struct mon_cfg cfg; > > /* > - * The value to add to the new reading to account for power management. > + * The value to add to the new reading to account for power management, > + * and overflow. > */ > u64 correction; > Reviewed-by: Zeng Heng