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 45F16C433EF for ; Mon, 10 Jan 2022 16:17:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237217AbiAJQRI (ORCPT ); Mon, 10 Jan 2022 11:17:08 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:44971 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237199AbiAJQRF (ORCPT ); Mon, 10 Jan 2022 11:17:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1641831423; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+YjTLY75U3Rr/IBjHhdFVsX4vnS2z8mb10E/ypAsx9o=; b=PbcmDbWHRMMQLyCXCr9uvOmvsHV8pR9MRroSlXczTyoKWOh4CAMd7oZUodO7FLYs/FTYiy LI+TCy1bBe2lvHwNgm64P45nx+gOwaXFYl0j4+L5X+UrR0WW0mBS/ScSN8QC1M4CqHyO/s jT40xCu2oY4Hf52eECufsxuGKj77GTE= Received: from mail-qv1-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-504-S8NcOPgDO2qG0R2GITO4zw-1; Mon, 10 Jan 2022 11:17:00 -0500 X-MC-Unique: S8NcOPgDO2qG0R2GITO4zw-1 Received: by mail-qv1-f69.google.com with SMTP id jn6-20020ad45de6000000b004146a2f1f97so12141335qvb.19 for ; Mon, 10 Jan 2022 08:17:00 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=+YjTLY75U3Rr/IBjHhdFVsX4vnS2z8mb10E/ypAsx9o=; b=xiM4lwHU+Df5Ut1W8NiwbsRLZiSwP3JXDhDJtlQ9VdMqP32R/kxKYpHARg69J8Q+ZE LhVuCLB4S6/GAbb7VtMcgt4pGKzVpBJd0yc/UA/3tfAeSVbKuiGP9qju17ZyxmBom9kX EzaCFQgeU5J3gcVU0Q4c6Bd7uRpou9DiZWIczF7+dBD7tn+A2WwceqvrhNdPf3HSgPgb fdK/wuOyEznnntnhe13O46Ne0gULVxSWBu7UsoTxvk6Do0WnTl73Nv0R1R3gJm19xmqe gacT0zyGtGS7FMa65iAwo/a/3xinFlI8sqG9eRDsujssl8QtwOs4yaBcTJuyGsWFiYSe G50w== X-Gm-Message-State: AOAM533NTg3GYi7QaDU3fEy/s9lW2gN1yhnDyRIJdAdKQj+LsCK37oSG cOjkBWETqTyWgXD44Ou744mShmqf/mVKx53o864jneheNXLnLuSHpLEQdUXWN7ooBMaBEDPWdvw dV0p3s3kvzmAEv3GRmtBZ6edn5w== X-Received: by 2002:ac8:5f4e:: with SMTP id y14mr377041qta.620.1641831420240; Mon, 10 Jan 2022 08:17:00 -0800 (PST) X-Google-Smtp-Source: ABdhPJyAUtzH3EEX9Ff3ydZLCMZTFVjkkVjbUCwm51dfml+s1g3fpFnx//1UUzWe5M/akiYa/jS9DA== X-Received: by 2002:ac8:5f4e:: with SMTP id y14mr377024qta.620.1641831420013; Mon, 10 Jan 2022 08:17:00 -0800 (PST) Received: from [192.168.1.9] (pool-68-163-101-245.bstnma.fios.verizon.net. [68.163.101.245]) by smtp.gmail.com with ESMTPSA id v13sm3080842qtk.93.2022.01.10.08.16.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Jan 2022 08:16:59 -0800 (PST) Subject: Re: [PATCH] livepatch: Avoid CPU hogging with cond_resched To: Song Liu Cc: David Vernet , live-patching@vger.kernel.org, open list , jpoimboe@redhat.com, pmladek@suse.com, jikos@kernel.org, mbenes@suse.cz References: <20211229215646.830451-1-void@manifault.com> <1f1b9b01-cfab-8a84-f35f-c21172e5d64d@redhat.com> From: Joe Lawrence Message-ID: <4df1f9a0-3b26-903b-fe63-af5e75ed98d4@redhat.com> Date: Mon, 10 Jan 2022 11:16:58 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On 1/7/22 11:46 AM, Song Liu wrote: > On Fri, Jan 7, 2022 at 6:13 AM Joe Lawrence wrote: >> >> On 12/29/21 4:56 PM, David Vernet wrote: >>> For example, under certain workloads, enabling a KLP patch with >>> many objects or functions may cause ksoftirqd to be starved, and thus for >>> interrupts to be backlogged and delayed. >> >> Just curious, approximately how many objects/functions does it take to >> hit this condition? While the livepatching kselftests are more about >> API and kernel correctness, this sounds like an interesting test case >> for some of the other (out of tree) test suites. > > Not many patched functions. We only do small fixes at the moment. In the recent > example, we hit the issue with ~10 patched functions. Another version > with 2 to 3 > patched function seems fine. > > Yes, I think this is an important test case. > Thanks, Song. If you can share any test setup details, I'll pass those along to our internal QE group. And once merged, we'll be adding this one to the list of backports for our distro. -- Joe