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 D50AAC433FE for ; Tue, 10 May 2022 01:48:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234344AbiEJBwn (ORCPT ); Mon, 9 May 2022 21:52:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231989AbiEJBwl (ORCPT ); Mon, 9 May 2022 21:52:41 -0400 Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 88B78140F8; Mon, 9 May 2022 18:48:45 -0700 (PDT) Received: from imladris.surriel.com ([96.67.55.152]) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1noEzN-0001Mi-5T; Mon, 09 May 2022 21:48:37 -0400 Message-ID: <5c3b6c2fc875708f1452b32416235247e11296af.camel@surriel.com> Subject: Re: [RFC] sched,livepatch: call stop_one_cpu in klp_check_and_switch_task From: Rik van Riel To: Josh Poimboeuf Cc: Song Liu , linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, jpoimboe@redhat.com, joe.lawrence@redhat.com, kernel-team@fb.com Date: Mon, 09 May 2022 21:48:36 -0400 In-Reply-To: <20220509200949.vzx4g5xpebomkok4@treble> References: <20220507174628.2086373-1-song@kernel.org> <20220509115227.6075105e@imladris.surriel.com> <20220509180004.zmvhz65xlncwqrrc@treble> <68f91fb233d5bf82e29cc5c6960a62863b297db3.camel@surriel.com> <20220509191745.yk2txsa4cv3ypf6k@treble> <1f94c48b4e0e7d73a689a076f78f0892095b4d89.camel@surriel.com> <20220509200949.vzx4g5xpebomkok4@treble> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-ilNaoEj4DrmQCmIflEKz" User-Agent: Evolution 3.42.4 (3.42.4-1.fc35) MIME-Version: 1.0 Sender: riel@shelob.surriel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-ilNaoEj4DrmQCmIflEKz Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2022-05-09 at 13:09 -0700, Josh Poimboeuf wrote: > To prevent patching, it would need to be some kind of sustained CPU > activity, rather than a burst.=C2=A0 I guess we haven't seen that show up > as > a real-world problem until now. >=20 It's amazing what you see when you have a few million very busy servers. The problems you think of as "one in a million" happen all the time :) > If you're able to identify which kthreads would be problematic, then > yeah, defining a "transition point" in their outer loops could be an > option. >=20 I'm in the middle of creating some scripts to gather kpatch output from all the systems, and then sort and count the results so we can easily see what the main pain points are. We'll be back with patches once we have the data in hand :) --=20 All Rights Reversed. --=-ilNaoEj4DrmQCmIflEKz Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAmJ5xHQACgkQznnekoTE 3oMARAf+N4u8+luoI5PmUGF85x4q2r/nIulQtv/wREpq0T4vUkHesfPH78VUZfAg GdYTkWEDSX4o5GRR9txs7aAoPUYy+H87YEiAWzwmmRsiuQVlu56NbqY4KK2pbspz 9BexZN15oC4yh2MEBGX/1BptB0JK0vgJNlDzzvBmXaQcBMvESgZ5A+Cg4NYCpY+u 0PQtmAaza3sKR63aNEllqwPJ9gGzE1fdnMsjDftKLIquX6ebR3Nju/yYkiNwWKup BL4ij2MtwrbgA4Z5fLfObhxL6bi4dmyLHjM3aVWpgJuOWtphUDSgO8th8yV/9ylw uLH+GwSAznoGRnqjYHwL85LAjqP68A== =Mhxs -----END PGP SIGNATURE----- --=-ilNaoEj4DrmQCmIflEKz--