From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2348587-1516653019-2-16331646319052187210 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='de', MailFrom='org' X-Spam-charsets: X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1516653018; b=AKQXZvfX0ubXpLpr+en+ERcSJH1CzASoLE+3EG/Rl2gg0X4 D9Ilj61jAfczia6p3MouJsy5FkG/3QI5ZlHHwldSZ6u0306wPuuaUoEI2QMizMQt pMKhPuH13MwCJtOeBVMJxF0fkQs60b3YtTplTPCQlSjDbyi4PJdAgELaO073yyBn s+4Sds3LiD1XYWFvf+EoG6fxOF1++RVY524ghA0ej066YH9rsxAxD7BElq6bVR3l /stm2sHIT5caUjfPx5o2r3DhTcRKrQAzufn499tgR1FEB2pCfMcEWkKk5wHne1bf 9Txq+iZUVdahOjBHkmYHS5U+0Ld0L2fFEu8Ikqg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id:sender :list-id; s=arctest; t=1516653018; bh=F4jtgAzodN62SQk213PsM4lZYE 5k1V0CqaOxqbe0X1M=; b=uNq+WgVKSoMPn1zVqLDSPV8rEZGVg/QxwqWP0E/LPh KxJRWNPrO423OuC3JUwmBv7ROMdSTX6nvNR1xfzPlzVXEx5ORA602QJzwWi3xiFC I4lasNz1Iqf/VmreNtoZn5NVVpfnIZhCgP7d37Jjy6mx8xg/EsHmTl1oKiOMxcyy srtWbkKOqyVctC13O+/nEBAZgd3M/Pj/E0jOk1ZKZdyLf43NBDgiVGa9PGza/Zg8 8Jr1kxtqCMBQaGsiHbDpTdf3+PN6G0QIMYCOgdHPUbqN8WoF3gNBHQSIfV2L0Hzm bHW/CRBe59/6U907+AVbZr0muNh7HttwddQhq8lt1S7Q== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=QcfcYZz1 x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=fail (message has been altered; 2048-bit rsa key sha256) header.d=infradead.org header.i=@infradead.org header.b=QcfcYZz1 x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=bombadil.20170209; dmarc=none (p=none,has-list-id=yes,d=none) header.from=lst.de; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=lst.de header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751046AbeAVUM5 (ORCPT ); Mon, 22 Jan 2018 15:12:57 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:39867 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751254AbeAVUMy (ORCPT ); Mon, 22 Jan 2018 15:12:54 -0500 From: Christoph Hellwig To: viro@zeniv.linux.org.uk Cc: Avi Kivity , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: aio poll, io_pgetevents and a new in-kernel poll API V4 Date: Mon, 22 Jan 2018 21:12:07 +0100 Message-Id: <20180122201243.31610-1-hch@lst.de> X-Mailer: git-send-email 2.14.2 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hi all, this series adds support for the IOCB_CMD_POLL operation to poll for the readyness of file descriptors using the aio subsystem. The API is based on patches that existed in RHAS2.1 and RHEL3, which means it already is supported by libaio. To implement the poll support efficiently new methods to poll are introduced in struct file_operations: get_poll_head and poll_mask. The first one returns a wait_queue_head to wait on (lifetime is bound by the file), and the second does a non-blocking check for the POLL* events. This allows aio poll to work without any additional context switches, unlike epoll. To make the interface fully useful a new io_pgetevents system call is added, which atomically saves and restores the signal mask over the io_pgetevents system call. It it the logical equivalent to pselect and ppoll for io_pgetevents. The corresponding libaio changes for io_pgetevents support and documentation, as well as a test case will be posted in a separate series. The changes were sponsored by Scylladb, and improve performance of the seastar framework up to 10%, while also removing the need for a privileged SCHED_FIFO epoll listener thread. The patches are on top of Als __poll_t annoations, so I've also prepared a git branch on top of those here: git://git.infradead.org/users/hch/vfs.git aio-poll.4 Gitweb: http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/aio-poll.4 Libaio changes: https://pagure.io/libaio.git io-poll Seastar changes (not updated for the new io_pgetevens ABI yet): https://github.com/avikivity/seastar/commits/aio Changes since V3: - remove the pre-sleep ->poll_mask call in vfs_poll, allow ->get_poll_head to return POLL* values. Changes since V2: - removed a double initialization - new vfs_get_poll_head helper - document that ->get_poll_head can return NULL - call ->poll_mask before sleeping - various ACKs - add conversion of random to ->poll_mask - add conversion of af_alg to ->poll_mask - lacking ->poll_mask support now returns -EINVAL for IOCB_CMD_POLL - reshuffled the series so that prep patches and everything not requiring the new in-kernel poll API is in the beginning Changes since V1: - handle the NULL ->poll case in vfs_poll - dropped the file argument to the ->poll_mask socket operation - replace the ->pre_poll socket operation with ->get_poll_head as in the file operations