From patchwork Fri Mar 8 04:21:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Imran Khan X-Patchwork-Id: 13586457 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C463E2C1A6; Fri, 8 Mar 2024 04:21:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.165.32 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709871714; cv=none; b=SfaXByT8XPCCfjHF2nIkkmWf1VYNuH27uFt3VCLrZDUNLGHOskn1pLNwcJE95z6h9t1GhIj/Hr0Bnzgeh6lcHxWTBQjoO4IbhuPURnjYrsvj6c+fKMNA68WPgIkB5Ugei8ta4znOg22AAvUs709t2HJIfaoCTirqif2kAa/Ip0U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709871714; c=relaxed/simple; bh=mmvy5azSDXUdowkCAJwabP8D5FIN7wVHZTgkJUorUzM=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=MyZaS9cyYCRfkLzjyVRHDe3qrlECQ7IWjhdJBqzqKw8UM0Fmlfcks60vXDYa4/x7aRonzfoohVtg0pEWVRBOQQMrXM82FXLQANtPzAE2LmeR26rQ30ee9WWwebi9pdlev/3oCMUeIlWHFzQWo5us+qd3QCIT5scRKaqLN3Dtoso= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=M8sqMQqu; arc=none smtp.client-ip=205.220.165.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="M8sqMQqu" Received: from pps.filterd (m0246617.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 4281iD0k011677; Fri, 8 Mar 2024 04:21:41 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=corp-2023-11-20; bh=r3Jellr22qKHaJrOAxSlScMDJSeEVcmcOkavqmzmZFY=; b=M8sqMQqu99cbQocSxLOE+VfcyScWk5Yzk6udXbYaDqFBlHRqiw4/WEIDC9vQKiZGN/El P1hpkD5nr/C00cgNjHjPs8LIzLUKtqoJciQRqbd00dSNIP33V2rqzJpbo+yodBE1cLeN LgFkaptOTe28aEjYGtbsbwVnkRipXd8ISgK5jaHQKjesImRMyTahiGuBUed3aV1oSGP1 MyPIJkMjn0VJjICKf4C59eQyGqMGeO0vsi0fFX5QgBB1RnnM9LIi2hTEPVBxDBG96UKx gCiQ83TmiJGgErJpT29gKDz/Nzx4BV66pKbcIyHnq9QVHeC7iBtbXYVhDRqPq7bNUbpO eQ== Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.appoci.oracle.com [138.1.114.2]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3wkvnv4yhr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 08 Mar 2024 04:21:40 +0000 Received: from pps.filterd (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 4282V5Bw016014; Fri, 8 Mar 2024 04:21:40 GMT Received: from localhost.localdomain (dhcp-10-191-134-242.vpn.oracle.com [10.191.134.242]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTP id 3wktjc7afj-1; Fri, 08 Mar 2024 04:21:39 +0000 From: Imran Khan To: viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH] eventpoll: record task that adds to monitor list. Date: Fri, 8 Mar 2024 15:21:36 +1100 Message-Id: <20240308042136.2739321-1-imran.f.khan@oracle.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-03-08_02,2024-03-06_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 adultscore=0 mlxlogscore=899 suspectscore=0 spamscore=0 malwarescore=0 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2403080031 X-Proofpoint-ORIG-GUID: EcklyHUXzSLfDqPZ-z_2W3r_y8bYcpH3 X-Proofpoint-GUID: EcklyHUXzSLfDqPZ-z_2W3r_y8bYcpH3 While debugging latency issues for task waiting on epoll_wait, sometimes it becomes necessary to see if the lower layer is invoking ep_poll_callback timely for a given pid or not. Recording task_struct in involved eppoll_entry's wait_queue_entry, allows us to check this using a probe (say dtrace) at this function. We could also achieve this by checking wait_queue_entry on eventpoll's wait_queue_head itself, but that would involve more indirections. Signed-off-by: Imran Khan --- Since it just helps in debugging, I have kept the patch RFC. fs/eventpoll.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 3534d36a1474..3d4faf0a2d25 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1287,6 +1287,8 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); pwq->whead = whead; pwq->base = epi; + pwq->wait.private = current; + if (epi->event.events & EPOLLEXCLUSIVE) add_wait_queue_exclusive(whead, &pwq->wait); else