From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-io1-f48.google.com (mail-io1-f48.google.com [209.85.166.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0FD5D13959C for ; Thu, 15 Feb 2024 16:10:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708013409; cv=none; b=G7Tr+A7fpteBNGaHEdREU3S225aWXzNslg1WSBt1M2hA7jaR0ta7iWgMS41UzIRi1uUKzKl+kNVgFCM1/Au+/48VHMCP+S+Bn8W6+x1fmuu4rqMTYn4XzsfoxnQAXr5jCVT2Qmq1BvAPfW1+sgFQx2LFtX68gfEUigeeSdisMf8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708013409; c=relaxed/simple; bh=LNmpqxV0YfHJbBxdYuunJibXydwG9f0jXBrhnN46hVI=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=PdDPNf0lBBdVWU+rEic5hQ4EV7b9nZx3WmaLR3gvO6gHFBej8UQKkYFmTTb6mpfpYPzYNv8Yc3/OPHWnsorCzGjWGFacm0Kex7bDNTgoAo7R5x9FwnDgKv2ytQ/DN/3tiDvSeOrRxxWN9DsHanh+V7OjnrQKgjKmf4te2khvaYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk; spf=pass smtp.mailfrom=kernel.dk; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b=s8AwGazo; arc=none smtp.client-ip=209.85.166.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="s8AwGazo" Received: by mail-io1-f48.google.com with SMTP id ca18e2360f4ac-7c49c979b5dso8385039f.1 for ; Thu, 15 Feb 2024 08:10:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1708013404; x=1708618204; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:from:to:cc:subject:date:message-id:reply-to; bh=rpijjQEzBgnLD/uY93UCJeV5MDh99Jzq/Yr+mGAGQm4=; b=s8AwGazowtQy+D5DoL6BwazbVwKeoFazz0Y3bmdSe0HjABLk4qjJ39unqaKXNkNw68 aJ7jy0VyoeB5okoeyfaUkKRrQ+L1buUGqiwfIR+3gj2z1OiA2V78br5+lcyHv42EJc/Z 7+OjPgSao6vbb1uuBkA92nyHawpfEbhp0n54xBeW1Q3umxlHEroEd0/amuE++Zb9Gf3r 1t80CaCuurO/V6JpanDIrY3OWZmEyJ7hqN/Lw6RPHJ+jZ39PS9hcd7ituTtSSadgGcj0 U1JkFM1kaljH886HRGTZOcC2LD/qnTxp6d4yf10uJMV9l5HScUjxhU0ueIA/7W6Pj4qU 7ZIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708013404; x=1708618204; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=rpijjQEzBgnLD/uY93UCJeV5MDh99Jzq/Yr+mGAGQm4=; b=O9zSAgxxtsXWMNAwyl3mgIXzlVLyZw4ocGxJKgj13ZBGVT8809mL4K2etQI0Wofvuf iIn9KzwZZbKlKlig+kvyt04vLJ+p57o9Yip0zzIOOnKCa3nIuGqV8f8Z9UoyyDny4iEF b/UD1SjgeWKdS2FYztGd3FejcUypOPiSxBu8kGislagBn73M70BX6J495g0moUJRVhzr rRxLx5fDyZ2v18OAJw1K+GG4QHRXBj6t+L8PmwbnnetdaTUQWR6alSnDyAXkDKgRjDwc kfwGIyFGQkFRZQtnlbxNtMgyguoX6FO1lI44jPYjf8LUa1KmKBYLN07QPVPYDaFZlwzO wf4g== X-Gm-Message-State: AOJu0YyJaC1iHNQrhajqzNJ12Z2+zWpJfc5LlKl9cFWcyKSlv+ZMqHVt mvJzkE1V92pw/02deD0dm13hcshnCI8ZAJbgwbxfbZ1cDSogz6gaF0oQ8XAAAj34IzQbZ1TvRbu D X-Google-Smtp-Source: AGHT+IEMX6gag3SN8iJXXG2PEk23g9jJ/oxQkXbCeksGUv1o4W8O7kSs4uk7sbb8SR92LNPDDauZ5g== X-Received: by 2002:a05:6e02:1c84:b0:363:ac1d:ae0f with SMTP id w4-20020a056e021c8400b00363ac1dae0fmr2208699ill.2.1708013404569; Thu, 15 Feb 2024 08:10:04 -0800 (PST) Received: from localhost.localdomain ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id x4-20020a056e02074400b0036275404ab3sm458524ils.85.2024.02.15.08.10.03 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Feb 2024 08:10:04 -0800 (PST) From: Jens Axboe To: io-uring@vger.kernel.org Subject: [PATCHSET v2 0/4] Add support for batched min timeout Date: Thu, 15 Feb 2024 09:06:55 -0700 Message-ID: <20240215161002.3044270-1-axboe@kernel.dk> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi, Normal CQE waiting is generally either done with a timeout, or without one. Outside of the timeout, the other key parameter is how many events to wait for. If we ask for N events and we get that within the timeout, then we return successfully. If we do not, then we return with -ETIME and the application can then check how many CQEs are actually available, if any. This works fine, but we're increasingly using smaller timeouts in applications for targeted batch waiting. Eg "give me N requests in T usec". If the application has other things do do every T usec, this works fine. But if it's an event loop that wants to process completions to make progress, it's pointless to return after T usec if there's nothing to do. The application can't really make T bigger reliably, as this may be the target it has to meet at busier times of the day. This patchset adds support for min timeout waiting, which adds a third parameter to how waits are done. The N and T timeout remain, but we add a min_timeout option, M. The batch is now defined by N and M. The application can now say "give me N requests in M usec, but if none have arrived, just sleep until T has passed". This allows for using a sane N+M, while avoid waking and returning all the time if nothing happens. The semantics are as follows: - If M expires and no events are available, keep waiting until T has expired. This is identical to using N+T without setting M at all, except if an event arrives after M has expired, we return immediately. - If M expires and events are available, return those even if it's less than N. - If N events arrive before M expires, return those events. This is identical to T == M, and M not being set. There's a liburing branch with test cases here: https://git.kernel.dk/cgit/liburing/log/?h=min-wait and the patches are on top of the current for-6.9/io_uring branch. They can also be viewed here: https://git.kernel.dk/cgit/linux/log/?h=io_uring-min-wait include/uapi/linux/io_uring.h | 3 +- io_uring/io_uring.c | 156 ++++++++++++++++++++++++++++------ io_uring/io_uring.h | 4 + 3 files changed, 134 insertions(+), 29 deletions(-) Changes since v1: - Fix issue with both min_wait and timeout, and transitioning to the long timeout. We'd add the current time potentially more than once, causing much longer waits than what was asked for. Test case has been added for that as well. -- Jens Axboe