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[23.128.96.18]) by mx.google.com with ESMTP id f2si10579397edl.256.2020.11.09.15.38.30; Mon, 09 Nov 2020 15:38:53 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2020-01-29 header.b=IgZm7EQM; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729585AbgKIXeu (ORCPT + 99 others); Mon, 9 Nov 2020 18:34:50 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:53188 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727311AbgKIXet (ORCPT ); Mon, 9 Nov 2020 18:34:49 -0500 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0A9NUIbl150038; Mon, 9 Nov 2020 23:32:33 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : references : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=FDH6vKmwAO2NQK037hjZRuPUy9YCEb1VTOoZECDQrmc=; b=IgZm7EQMUyh+OeNBObS9P0PfLmf8JHwTxGFAjApC24xsJzoU1jw6XRrG7Xl+Jylyt+2v RFz1P1yxHxMmq4AlZGuvoz0IEebpztZIbcw6Dus7KMgaGwtMzdtafnLw8I0XdquR++9h hwMrD6OD6wTVY4MvxgeWi9WIL7SPGhIt3Q5LzKro4LJxsTVFYNMl9Br3nIU0RZOQ6oY1 KGUv/rk8uJMjynLQ2qFVkhVNfALQVbHkm0BJ2F3I4biQsOASqtbRaxe/NtiBzjJqDMaZ amDK4fs5AbzE65/xQvNvz5L84+1ZURPgJ/292mZ2afO4j05TzYfXsxfhxZYBQjk3Casu GA== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by aserp2130.oracle.com with ESMTP id 34nh3as1y6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 09 Nov 2020 23:32:33 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0A9NOnOn085072; Mon, 9 Nov 2020 23:30:32 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3020.oracle.com with ESMTP id 34p5fyda9u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 09 Nov 2020 23:30:32 +0000 Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 0A9NUHbw020143; Mon, 9 Nov 2020 23:30:19 GMT Received: from [192.168.0.193] (/69.207.174.138) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 09 Nov 2020 15:30:17 -0800 Subject: Re: [PATCH v8 -tip 17/26] sched: Split the cookie and setup per-task cookie on fork From: chris hyser To: "Joel Fernandes (Google)" , Nishanth Aravamudan , Julien Desfossez , Peter Zijlstra , Tim Chen , Vineeth Pillai , Aaron Lu , Aubrey Li , tglx@linutronix.de, linux-kernel@vger.kernel.org Cc: mingo@kernel.org, torvalds@linux-foundation.org, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Phil Auld , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , vineeth@bitbyteword.org, Chen Yu , Christian Brauner , Agata Gruza , Antonio Gomez Iglesias , graf@amazon.com, konrad.wilk@oracle.com, dfaggioli@suse.com, pjt@google.com, rostedt@goodmis.org, derkling@google.com, benbjiang@tencent.com, Alexandre Chartre , James.Bottomley@hansenpartnership.com, OWeisse@umich.edu, Dhaval Giani , Junaid Shahid , jsbarnes@google.com, Aubrey Li , "Paul E. McKenney" , Tim Chen References: <20201020014336.2076526-1-joel@joelfernandes.org> <20201020014336.2076526-18-joel@joelfernandes.org> Message-ID: Date: Mon, 9 Nov 2020 18:30:12 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9800 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 malwarescore=0 adultscore=0 phishscore=0 bulkscore=0 mlxlogscore=999 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011090148 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9800 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 priorityscore=1501 clxscore=1015 malwarescore=0 mlxscore=0 spamscore=0 suspectscore=0 mlxlogscore=999 impostorscore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011090149 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/4/20 5:30 PM, chris hyser wrote: > On 10/19/20 9:43 PM, Joel Fernandes (Google) wrote: >> In order to prevent interference and clearly support both per-task and CGroup >> APIs, split the cookie into 2 and allow it to be set from either per-task, or >> CGroup API. The final cookie is the combined value of both and is computed when >> the stop-machine executes during a change of cookie. >> >> Also, for the per-task cookie, it will get weird if we use pointers of any >> emphemeral objects. For this reason, introduce a refcounted object who's sole >> purpose is to assign unique cookie value by way of the object's pointer. >> >> While at it, refactor the CGroup code a bit. Future patches will introduce more >> APIs and support. >> >> Tested-by: Julien Desfossez >> Signed-off-by: Joel Fernandes (Google) >> --- >>   include/linux/sched.h |   2 + >>   kernel/sched/core.c   | 241 ++++++++++++++++++++++++++++++++++++++++-- >>   kernel/sched/debug.c  |   4 + >>   3 files changed, 236 insertions(+), 11 deletions(-) >> >> diff --git a/include/linux/sched.h b/include/linux/sched.h >> index fe6f225bfbf9..c6034c00846a 100644 >> --- a/include/linux/sched.h >> +++ b/include/linux/sched.h >> @@ -688,6 +688,8 @@ struct task_struct { >>   #ifdef CONFIG_SCHED_CORE >>       struct rb_node            core_node; >>       unsigned long            core_cookie; >> +    unsigned long            core_task_cookie; >> +    unsigned long            core_group_cookie; >>       unsigned int            core_occupation; >>   #endif >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index bab4ea2f5cd8..30a9e4cb5ce1 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -346,11 +346,14 @@ void sched_core_put(void) >>       mutex_unlock(&sched_core_mutex); >>   } >> +static int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2); >> + >>   #else /* !CONFIG_SCHED_CORE */ >>   static inline void sched_core_enqueue(struct rq *rq, struct task_struct *p) { } >>   static inline void sched_core_dequeue(struct rq *rq, struct task_struct *p) { } >>   static bool sched_core_enqueued(struct task_struct *task) { return false; } >> +static int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2) { } >>   #endif /* CONFIG_SCHED_CORE */ >> @@ -3583,6 +3586,20 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) >>   #endif >>   #ifdef CONFIG_SCHED_CORE >>       RB_CLEAR_NODE(&p->core_node); >> + >> +    /* >> +     * Tag child via per-task cookie only if parent is tagged via per-task >> +     * cookie. This is independent of, but can be additive to the CGroup tagging. >> +     */ >> +    if (current->core_task_cookie) { >> + >> +        /* If it is not CLONE_THREAD fork, assign a unique per-task tag. */ >> +        if (!(clone_flags & CLONE_THREAD)) { >> +            return sched_core_share_tasks(p, p); >> +               } >> +        /* Otherwise share the parent's per-task tag. */ >> +        return sched_core_share_tasks(p, current); >> +    } >>   #endif >>       return 0; >>   } sched_core_share_tasks() looks at the value of the new tasks core_task_cookie which is non-zero on a process or thread clone and causes underflow for both the enable flag itself and for cookie ref counts. So just zero it in __sched_fork(). -chrish ------ sched: zero out the core scheduling cookie on clone As the cookie is reference counted, even if inherited, zero this and allow explicit sharing. Signed-off-by: Chris Hyser --- kernel/sched/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index fd3cc03..2af0ea6 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3378,6 +3378,9 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p) p->capture_control = NULL; #endif init_numa_balancing(clone_flags, p); +#ifdef CONFIG_SCHED_CORE + p->core_task_cookie = 0; +#endif #ifdef CONFIG_SMP p->wake_entry.u_flags = CSD_TYPE_TTWU; #endif