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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EDB19C433F5 for ; Tue, 9 Nov 2021 16:32:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D223361215 for ; Tue, 9 Nov 2021 16:32:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235468AbhKIQex (ORCPT ); Tue, 9 Nov 2021 11:34:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235804AbhKIQex (ORCPT ); Tue, 9 Nov 2021 11:34:53 -0500 Received: from mail-lj1-x22f.google.com (mail-lj1-x22f.google.com [IPv6:2a00:1450:4864:20::22f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8D9DC061764 for ; Tue, 9 Nov 2021 08:32:06 -0800 (PST) Received: by mail-lj1-x22f.google.com with SMTP id 1so37427992ljv.2 for ; Tue, 09 Nov 2021 08:32:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=M/8dhRfwJVa4DbGul2wXDZMaW1G+0u9Zho02c+0fbvg=; b=i1zsHWvak0Z48bvXbSLAUT9qTUMXTZ/9dt4BWp0/Q5HLRsomYkzEeQm2ZeJhdLWGCv Gs9JaLDadSe+Zj5Jy3m5Y12u+A80/Qko0FnXeWbpwqvcxei2dfio3K6a0wLJi9PLR+MD tPFd57zm+C6gXyXBKIxRFhG6NL7YkBV+JXggQGswjgXIuhL0iMK82zv6Fa+lvA5iDu3d bJrm67+kGoOb7M0RqYvkhRgXePsjif9FZhUzQ0Tc34ssVGmWyMDFg+vPoG1ZWZETxPjj rX5ke2p7xfpXQDLbQyYyNXn7fR5Wwn6Gs8A9vp2kO1C/C0caI4YqRTvYHSQ7Qwt6ZoFL eH/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=M/8dhRfwJVa4DbGul2wXDZMaW1G+0u9Zho02c+0fbvg=; b=ZeVHPETjjunXRShHsx14XRH/13DB5zK3FnvofEatxPK12VBuLgSSUt/Wotek4NpGnK YAv3QoUyWMtxw736HiBfEey68e4SKDlMz0Qi14vd2snJOJPNBCb+2LR2tA4h/gR8AY7s Xy7/06cyqUvsZjhiLWxqFrPDs2EHgH8mRX/b8F95HeUptyZj4Glxw1W7WHjb1wl5O5kH V6cj9gCJiiLwb151ItcFCMTyCAWbSIkfcNdmRh3iLHBvspa1D9cyILBvP8NsubPXy6px BEHg279qYCmBOWmDR/h1If5w1q83E5kiBWrHppG2aKTiP5+OSmGC2xUG54WfZzcpgbFm yGFw== X-Gm-Message-State: AOAM530XQN0kpZfUcFB7xKHFcCHMIdaPuaagnZpMtuE64v4stliiOt7X mtDaRoVnJ9bMun6GDR0Sw3xWa1gWQDu6wk7Nlamifw== X-Google-Smtp-Source: ABdhPJzlzPHziQ7RTqVxchkRg4XOW7Q7HSp1BAF/VSiFuVRmTDjCPXv+cBjfftIRsY+yBCXKUVkRTXptkfRPlKkrijM= X-Received: by 2002:a05:651c:1101:: with SMTP id d1mr9135458ljo.373.1636475524928; Tue, 09 Nov 2021 08:32:04 -0800 (PST) MIME-Version: 1.0 References: <20211104195804.83240-1-posk@google.com> In-Reply-To: From: Peter Oskolkov Date: Tue, 9 Nov 2021 08:31:53 -0800 Message-ID: Subject: Re: [PATCH v0.8 0/6] sched,mm,x86/uaccess: implement User Managed Concurrency Groups To: Barry Song <21cnbao@gmail.com> Cc: posk@posk.io, Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Andrew Morton , Dave Hansen , Andy Lutomirski , Linux-MM , LKML , linux-api@vger.kernel.org, Paul Turner , Ben Segall , Andrei Vagin , Jann Horn , Thierry Delisle Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Hi Barry, [...] > > Do you have a real workload or an example application using UMCG? > [...] A google-internal variant of UMCG kernel patches is used extensively to enable user-space scheduling of heterogeneous work items. The main use case is services that need to ensure user isolation; in addition, latency vs throughput workloads served by the same service are also well addressed by user-space schedulers. For example, a DBMS needs to ensure that one "hungry" user does not adversely affect other well-behaved users; but at the same time if the overall load is relatively low, users are allowed to go ahead and consume as much CPU as possible, as long as this does not affect other users negatively. Services that treat their work uniformly, and care only about raw throughput, usually do not benefit from custom user-space scheduling that UMCG, or similar, enables. Thanks, Peter