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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBFFBC41513 for ; Mon, 24 Jul 2023 15:35:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231355AbjGXPf4 (ORCPT ); Mon, 24 Jul 2023 11:35:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229544AbjGXPfz (ORCPT ); Mon, 24 Jul 2023 11:35:55 -0400 Received: from mail-oo1-xc2b.google.com (mail-oo1-xc2b.google.com [IPv6:2607:f8b0:4864:20::c2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13BAFB1 for ; Mon, 24 Jul 2023 08:35:54 -0700 (PDT) Received: by mail-oo1-xc2b.google.com with SMTP id 006d021491bc7-56584266c41so2734081eaf.2 for ; Mon, 24 Jul 2023 08:35:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=raspberrypi.com; s=google; t=1690212953; x=1690817753; h=cc:to:subject:message-id:date:from:mime-version:from:to:cc:subject :date:message-id:reply-to; bh=oKZv/rBmUS8jYpb20v0bLOMjZtXNWMA7dW9EuTAoCFk=; b=kXfW6CLF0OSdXza+/b10cNHYYi7dagRWPLZb23nfItK9QmOO0FcMPU1H66eUvcqi5m bVsNXcfUT4MsQ6YXPWMS+dUmtY8E8GTiNz5KEBVJZMIF3LF/ruzurtduAsbiDsowpTGP 2d/VlfNHqamUE4ayamTMkT/jzy39DAKXe0idnmfQ8OhhqCRYoI8CQNDMtO2QY57bHYDb RQ26AYVeyU+meLr02jrmMkgcpae0j3wVXw5OEriXC4X5Mz46RTCz+KAAWauCYacpIh0y iHZe1DrQRBC9GJT8z2t89iuj1ihdutxQUec4Hqi4y1stF472GRok/pziJAu7mjqljp1T FJLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690212953; x=1690817753; h=cc:to:subject:message-id:date:from:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=oKZv/rBmUS8jYpb20v0bLOMjZtXNWMA7dW9EuTAoCFk=; b=SwbdoQ9tdIIBcTe821zciHv7+IVuomoAocy7xGzYccgKbBz0ffb9DR6wrPwECn5/9U Bwq8Cj+TXE8WSpHkSyIw659CdvKdmgEb1gbtS3GuNvpfpVlQozK1dtHIfpAMhBzAiqDB obC5QQ3W1FuYAUBg3gQJSMZXyAlGiKdcIdo13G4T4tY12W6gOwOwAVYcJmbbJNey6Slw 5IVx9HJJDXfj213+2xPZOghvVyIxWshJPWYtN99k/m9p2H3d32WX+pBhF+QqgOsCwAEZ UbAnKHoOy1U04Ttg66MTSVdLPHoBv9ke/7y0iZ9mc6vGXbu4cKKlAQxm9G4g/pNaQ9Pe 0xBw== X-Gm-Message-State: ABy/qLanykS1rJrj7/Zcyrouljf5X+2v0ZSrvcrKK0IPX9AKe3uSFaLT InUqwa2HSYSwMZVV/gV7UedSVwsJxv3BOQP6dqrvSA== X-Google-Smtp-Source: APBJJlFC27Fs2FQEX6/uDWYX3uVjauBNtGtTmosdOo0LpcFraWNWeDabeLTKObjIMXvb/cfgKzxEeXkoh90w1rflBig= X-Received: by 2002:a05:6808:f01:b0:398:34da:daad with SMTP id m1-20020a0568080f0100b0039834dadaadmr13502844oiw.51.1690212953373; Mon, 24 Jul 2023 08:35:53 -0700 (PDT) MIME-Version: 1.0 From: Phil Elwell Date: Mon, 24 Jul 2023 16:35:43 +0100 Message-ID: Subject: Re: [PATCH] io_uring: Use io_schedule* in cqring wait To: axboe@kernel.dk Cc: andres@anarazel.de, asml.silence@gmail.com, david@fromorbit.com, hch@lst.de, io-uring@vger.kernel.org, LKML , linux-xfs@vger.kernel.org, stable Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Hi Andres, With this commit applied to the 6.1 and later kernels (others not tested) the iowait time ("wa" field in top) in an ARM64 build running on a 4 core CPU (a Raspberry Pi 4 B) increases to 25%, as if one core is permanently blocked on I/O. The change can be observed after installing mariadb-server (no configuration or use is required). After reverting just this commit, "wa" drops to zero again. I can believe that this change hasn't negatively affected performance, but the result is misleading. I also think it's pushing the boundaries of what a back-port to stable should do. Phil