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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FAD9C433F5 for ; Wed, 24 Nov 2021 17:20:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 148996B0075; Wed, 24 Nov 2021 12:20:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0F8FE6B0078; Wed, 24 Nov 2021 12:20:39 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F04676B007B; Wed, 24 Nov 2021 12:20:38 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0051.hostedemail.com [216.40.44.51]) by kanga.kvack.org (Postfix) with ESMTP id E26E46B0075 for ; Wed, 24 Nov 2021 12:20:38 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A435E184E6425 for ; Wed, 24 Nov 2021 17:20:28 +0000 (UTC) X-FDA: 78844487694.24.32B3E55 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) by imf26.hostedemail.com (Postfix) with ESMTP id 3451C20019EE for ; Wed, 24 Nov 2021 17:20:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=90tBr9ISWVQ5VDnzn6BH4Jf8y5Ik/rvCK0jtS5q55bg=; b=T7x+cr74AzzFRTsIXSBUlC1rKX LEa1lEVdZsUkgySFF41gbe3HBB0rK5KLFnC+g6oTXxChVVuJzDf+9qeRu8H7Y6tGtWUTHDvWQL/Qf +FHGxt8YnkRa9VPidqhxPCd/YpEd6Fdqy2nbaN7VnuytIXlzhI+qGmL5Mu8yJevyiKMRAo4amvsqz /NrGH6raItx9mDtEl46I3ozPT5allOhkyCPkd5/QGI986JQU5TNPfO0RNa837MvmofcDnsAhNN/em W3UXw7LfiWAO9M6gG7KdgiSBWceGMPIPsyhiRCd0kkGjRetF1R6016ZZk9daXvDZADZoz07/ms33L NvuyILgg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mpvwS-000I2u-Af; Wed, 24 Nov 2021 17:20:20 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (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) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id A24C3300093; Wed, 24 Nov 2021 18:20:18 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8BD202DABEF09; Wed, 24 Nov 2021 18:20:18 +0100 (CET) Date: Wed, 24 Nov 2021 18:20:18 +0100 From: Peter Zijlstra To: Peter Oskolkov Cc: Ingo Molnar , Thomas Gleixner , Andrew Morton , Dave Hansen , Andy Lutomirski , Linux Memory Management List , Linux Kernel Mailing List , linux-api@vger.kernel.org, Paul Turner , Ben Segall , Peter Oskolkov , Andrei Vagin , Jann Horn , Thierry Delisle Subject: Re: [PATCH v0.9.1 0/6] sched,mm,x86/uaccess: implement User Managed Concurrency Groups Message-ID: References: <20211122211327.5931-1-posk@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 3451C20019EE X-Stat-Signature: 9m18138npj4446n9m3ujxjw4kxuh1uqd Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=infradead.org header.s=desiato.20200630 header.b=T7x+cr74; spf=none (imf26.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.92.199) smtp.mailfrom=peterz@infradead.org; dmarc=none X-HE-Tag: 1637774426-1832 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Nov 24, 2021 at 08:28:43AM -0800, Peter Oskolkov wrote: > On Wed, Nov 24, 2021 at 6:06 AM Peter Zijlstra wrote: > > > > On Mon, Nov 22, 2021 at 01:13:21PM -0800, Peter Oskolkov wrote: > > > User Managed Concurrency Groups (UMCG) is an M:N threading > > > subsystem/toolkit that lets user space application developers implement > > > in-process user space schedulers. > > > > > > This v0.9.1 patchset is the same as v0.9, where u32/u64 in > > > uapi/linux/umcg.h are replaced with __u32/__u64, as test robot/lkp > > > does not recognize u32/u64 for some reason. > > > > > > v0.9 is v0.8 rebased on top of the current tip/sched/core, > > > with a fix in umcg_update_state of an issue reported by Tao Zhou. > > > > > > Key changes from patchset v0.7: > > > https://lore.kernel.org/all/20211012232522.714898-1-posk@google.com/: > > > > > > - added libumcg tools/lib/umcg; > > > - worker "wakeup" is reworked so that it is now purely a userspace op, > > > instead of waking the thread in order for it to block on return > > > to the userspace immediately; > > > - a couple of minor fixes and refactorings. > > > > > > These big things remain to be addressed (in no particular order): > > > - support tracing/debugging > > > - make context switches faster (see umcg_do_context_switch in umcg.c) > > > - support other architectures > > > - cleanup and post selftests in tools/testing/selftests/umcg/ > > > - allow cross-mm wakeups (securely) > > > > *groan*... so these patches do *NOT* support the very thing this all > > started with, namely block + wakeup notifications. I'm really not sure > > how that happened, as that was the sole purpose of the exercise. > > I'm not sure why you say this - in-process block/wakeup is very much > supported - please see the third patch. Cross-process (cross-mm) > wakeups are not supported at the moment, as the security story has to > be fleshed out. I seem to have gotten submit and update work confused. I'll go stare more. For some reason I find it very hard to read this stuff.