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 77D89C4332F for ; Mon, 30 Oct 2023 12:56:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 06BA56B01F1; Mon, 30 Oct 2023 08:56:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 01B966B01F2; Mon, 30 Oct 2023 08:56:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E4C8A6B01F3; Mon, 30 Oct 2023 08:56:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id D64F86B01F1 for ; Mon, 30 Oct 2023 08:56:35 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 8FA45120944 for ; Mon, 30 Oct 2023 12:56:35 +0000 (UTC) X-FDA: 81402126750.30.0E861AE Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) by imf26.hostedemail.com (Postfix) with ESMTP id A294C14000A for ; Mon, 30 Oct 2023 12:56:33 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=efficios.com header.s=smtpout1 header.b=fE3NbRc9; spf=pass (imf26.hostedemail.com: domain of mathieu.desnoyers@efficios.com designates 167.114.26.122 as permitted sender) smtp.mailfrom=mathieu.desnoyers@efficios.com; dmarc=pass (policy=none) header.from=efficios.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1698670593; a=rsa-sha256; cv=none; b=wJNo33mHiTUYUqNH3jfs2jAxddV+cHkjiwGOkFfYq+nxs87JAlj59ivouc19ejV95afwBl V3BLdpPJN3htxAS15IODZjlTSqY3O58KmoumyA66tPGjpSW+Wk6WQZWEIl6XgARnJ9RrN4 um92HyfVkc1lq87QeGIffdUC8VWkPr0= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=efficios.com header.s=smtpout1 header.b=fE3NbRc9; spf=pass (imf26.hostedemail.com: domain of mathieu.desnoyers@efficios.com designates 167.114.26.122 as permitted sender) smtp.mailfrom=mathieu.desnoyers@efficios.com; dmarc=pass (policy=none) header.from=efficios.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1698670593; h=from:from:sender: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:dkim-signature; bh=yTEaEQCCt25IJ50qTmOgK4mpdEgdJaxM+ZjLXFOA6tg=; b=LrmGZGkuoWnaKPpWcKzlHwLFEySuxrOu7WUn3V8JIKS1EtprXeSds9gaNESGKWj+i0roKh 6L/NlklKz8TVPk1cCRIH5BkWEuYbwCXdPUpGDn53SBmwbcslFDwS4wc30GxSzhxTV8ODqD sMcCK8dWCv/os2J8EsVTVlP5GWKFeJ8= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1698670592; bh=sTuGSzxlodREgxcS2UWzIxTYJ0GN5DcFjE0VtX76IPs=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=fE3NbRc9/1Qae9xJ15f2b8QPi3Jz7XjazZFaXa7xTg/aPoR5Pa2E5+Ibx/akSB1Gx 9IDAnNU9lfazAasXyaIbFdcXYC27nZiqy/Tb0zgMAtedAVZ68OZBs3CofgdZ92T66F Fh2N73pltZ7zros/GUN/mqYl3qR756zzawajm2xO6/6cmdafuYqmRss9VgaDmUkWEr OaKd5Vn9vlvtyadkFqVOo2SCX+17pDDB1ft6PCLf+T/bonkze/qJ/+LngEcmIzROkb 3Y/zkZG/4hODUOHZyyL9OXY7tILFfZIqKcBCSEIllQMFbJMhpZy4vFVq+vnqMvlJXb sxbld5/DpSrvg== Received: from [IPV6:2606:6d00:100:4000:2d85:44b8:ccb0:e487] (unknown [IPv6:2606:6d00:100:4000:2d85:44b8:ccb0:e487]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4SJtZ82FF0z1Zr7; Mon, 30 Oct 2023 08:56:32 -0400 (EDT) Message-ID: Date: Mon, 30 Oct 2023 08:56:50 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [POC][RFC][PATCH v2] sched: Extended Scheduler Time Slice Content-Language: en-US To: Steven Rostedt Cc: Linus Torvalds , Peter Zijlstra , LKML , Thomas Gleixner , Ankur Arora , linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, willy@infradead.org, mgorman@suse.de, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com, Joel Fernandes , Youssef Esmat , Vineeth Pillai , Suleiman Souhlal , Ingo Molnar , Daniel Bristot de Oliveira References: <20231025235413.597287e1@gandalf.local.home> <20231026105944.GJ33965@noisy.programming.kicks-ass.net> <20231026071413.4ed47b0e@gandalf.local.home> <7871472b-a0c4-4475-9671-69a3244f956d@efficios.com> <20231026164549.14d45c60@gandalf.local.home> <644da047-2f7a-4d55-a339-f2dc28d2c852@efficios.com> <20231027122442.5c76dd62@gandalf.local.home> <20231027124930.3753cdd4@gandalf.local.home> From: Mathieu Desnoyers In-Reply-To: <20231027124930.3753cdd4@gandalf.local.home> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A294C14000A X-Stat-Signature: 8tdfn39u5i3bj8nstzpmcngocebqnss1 X-Rspam-User: X-HE-Tag: 1698670593-817876 X-HE-Meta: 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 nV1127f/ tZE/dpgZgo0k9F9eg3t9bX8VLAsUMBF8IFkE2opxs8gO7Anzuzbuusja5bbConE6UQqOH6tvv513so02fILbbFv8D4/fXvGJxChbecLBHV+rur2Ne8fZFPLxVBUTuPPJMqcXQZDPGO07y6bycHytON++nf5P1qLq8iVAxyrLUOVsBUeq8QqaUNyUf7eOjlGAKXQA40rCDVvvKdfc6uFjCUt3k+3lOhHhD6ATO0Sj0ZreViJdCj9cKj3X0yivF28zMJmnV99wb8wL+6KX3pPDd+5eKZ5AHyx7ohxrL4D9RA5q4eayE51BY8GssjgKwy1CTN6A8 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: List-Subscribe: List-Unsubscribe: On 2023-10-27 12:49, Steven Rostedt wrote: > On Fri, 27 Oct 2023 12:35:56 -0400 > Mathieu Desnoyers wrote: > >>> Does that make more sense? >> >> Not really. >> >> Please see my other email about the need for a reference count here, for >> nested locks use-cases. > > Note, my original implementation of nested locking was done completely in > user space. > > int __thread lock_cnt; > > extend() { > if (lock_cnt++) > return; > ... > } > > unextend() { > if (--lock_cnt) > return; > ... > } This only works if "your" lock implementation is the only user of this RSEQ feature within a process. RSEQ requires that multiple libraries can share the facilities. Therefore, the rseq field should include the nesting counter as part of the RSEQ ABI so various userspace libraries can use it collaboratively. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com