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 731A5C001DE for ; Sun, 23 Jul 2023 18:06:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229591AbjGWSGj (ORCPT ); Sun, 23 Jul 2023 14:06:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229597AbjGWSGi (ORCPT ); Sun, 23 Jul 2023 14:06:38 -0400 Received: from vulcan.natalenko.name (vulcan.natalenko.name [104.207.131.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E39BE4E; Sun, 23 Jul 2023 11:06:35 -0700 (PDT) Received: from spock.localnet (unknown [94.142.239.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by vulcan.natalenko.name (Postfix) with ESMTPSA id B39F1146A156; Sun, 23 Jul 2023 20:06:31 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=dkim-20170712; t=1690135591; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3/Q/y5BV8s5ndvdwgTPFAV48mdLYdi966EHVL5SMeGI=; b=Pv734e6/iyPncmGFhKp0bb4K4GsE9nFzNmu1Zua8pWm+5U43vGsYmnUwLaFUNIyWk0NUdS gwtAItr210eX8w/x2q504TDgN4bL9WhaHpwpU/DJMWM0tCDwU0kHiy1QRD1RfNZE+iIelB wV0dJ5KKNd1u0F5ktzk+YPQJE+xEFaI= From: Oleksandr Natalenko To: Jens Axboe , stable@vger.kernel.org, Genes Lists Cc: Greg Kroah-Hartman , Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, Andres Freund Subject: Re: [PATCH 6.4 800/800] io_uring: Use io_schedule* in cqring wait Date: Sun, 23 Jul 2023 20:06:19 +0200 Message-ID: <2691683.mvXUDI8C0e@natalenko.name> In-Reply-To: <70e5349a-87af-a2ea-f871-95270f57c6e3@sapience.com> References: <20230716194949.099592437@linuxfoundation.org> <538065ee-4130-6a00-dcc8-f69fbc7d7ba0@kernel.dk> <70e5349a-87af-a2ea-f871-95270f57c6e3@sapience.com> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart12252023.O9o76ZdvQC"; micalg="pgp-sha256"; protocol="application/pgp-signature" Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org --nextPart12252023.O9o76ZdvQC Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8"; protected-headers="v1" From: Oleksandr Natalenko Date: Sun, 23 Jul 2023 20:06:19 +0200 Message-ID: <2691683.mvXUDI8C0e@natalenko.name> In-Reply-To: <70e5349a-87af-a2ea-f871-95270f57c6e3@sapience.com> MIME-Version: 1.0 Hello. On ned=C4=9Ble 23. =C4=8Dervence 2023 19:43:50 CEST Genes Lists wrote: > On 7/23/23 11:31, Jens Axboe wrote: > ... > > Just read the first one, but this is very much expected. It's now just > > correctly reflecting that one thread is waiting on IO. IO wait being > > 100% doesn't mean that one core is running 100% of the time, it just > > means it's WAITING on IO 100% of the time. > >=20 >=20 > Seems reasonable thank you. >=20 > Question - do you expect the iowait to stay high for a freshly created=20 > mariadb doing nothing (as far as I can tell anyway) until process=20 > exited? Or Would you think it would drop in this case prior to the=20 > process exiting. >=20 > For example I tried the following - is the output what you expect? >=20 > Create a fresh mariab with no databases - monitor the core showing the=20 > iowaits with: >=20 > mpstat -P ALL 2 100 >=20 > # rm -f /var/lib/mysql/* > # mariadb-install-db --user=3Dmysql --basedir=3D/usr --datadir=3D/var/lib= /mysql >=20 > # systemctl start mariadb (iowaits -> 100%)=20 > =20 >=20 > # iotop -bo |grep maria (shows no output, iowait stays 100%) >=20 > (this persists until mariadb process exits) > =20 >=20 > # systemctl stop mariadb (iowait drops to 0%)=20 This is a visible userspace behaviour change with no changes in the userspa= ce itself, so we cannot just ignore it. If for some reason this is how it s= hould be now, how do we explain it to MariaDB devs to get this fixed? Thanks. =2D-=20 Oleksandr Natalenko (post-factum) --nextPart12252023.O9o76ZdvQC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEZUOOw5ESFLHZZtOKil/iNcg8M0sFAmS9bBsACgkQil/iNcg8 M0um0g//ajPoGUR8cLcGZ2a+l4uWXZyDdD8YMAzNwnb02ovSl7doi1V1z5BA9Kx6 Q64wfedIE5FNPHfVRoORIx29zbOWFOw7qXu4AGi5IR01teIvTfZhYtXoEahhUL8S hu+SCSqCR5mO6o99Nx+Zhen4dc41oOUKVEfPRv9w4CpZNN1ou+w7mMkaXM3S3pme cTSoBDW6ftKyVIpV0z3vDQXw1+dqPVTZJ9KAYgqeIsxrTYHY3kEdgjy2wcxKXo6u KHNyxc8jLfm2QQDBeX7iHTB3PH9H8+Ajes059DvBjqvG3Oe7tcxIKsRF6Q8mt/9F gKAs3vpJ7r/ORB0aFcTTOjteuN51nl6dsGpOay3ltT86+BmqJQaHuUc7whILXKIa qxzCZj7C+PaXQ7Q3agUAYWS6XNz4BYeqOkMFPpHYcESUpnVbJnNfs+1CuGWhelpy OuGQ/RafxbThkmoSUdX8mFM+WMYdVyQDSDZhqqrhENMgd2VxY17FkbWipMwQw4oT /yzQWGm4n+9YzWm8/bBLTo5A254ZuizIDIYsitSYPp1kd+wf+9NZkQ2+m3Z1b/mQ nvp04Xs0XCgu8LxVe3Gfr+ri4axrIC1xkYrxdiPH/hroKdFpLuuh/yg4BG52OrSW u/oFkF9FvwbMwcixWJy8mrGVcwyQzn1XtDOBxyNaKhgdJfoMVgc= =bqKi -----END PGP SIGNATURE----- --nextPart12252023.O9o76ZdvQC--