From nobody Tue Nov 30 11:53:20 2021 X-Original-To: freebsd-hackers@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 66E9D18B3F82 for ; Tue, 30 Nov 2021 11:53:25 +0000 (UTC) (envelope-from se@freebsd.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4J3LFx1DJvz4d7c; Tue, 30 Nov 2021 11:53:25 +0000 (UTC) (envelope-from se@freebsd.org) Received: from [IPV6:2003:cd:5f2e:2500:fc0c:6aa2:fcd3:b0c3] (p200300cd5f2e2500fc0c6aa2fcd3b0c3.dip0.t-ipconnect.de [IPv6:2003:cd:5f2e:2500:fc0c:6aa2:fcd3:b0c3]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: se/mail) by smtp.freebsd.org (Postfix) with ESMTPSA id 97B0951D7; Tue, 30 Nov 2021 11:53:24 +0000 (UTC) (envelope-from se@freebsd.org) Message-ID: Date: Tue, 30 Nov 2021 12:53:20 +0100 List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: Call for Foundation-supported Project Ideas Content-Language: en-US To: Joseph Mingrone , FreeBSD Hackers References: <861r36xzpe.fsf@phe.ftfl.ca> From: Stefan Esser In-Reply-To: <861r36xzpe.fsf@phe.ftfl.ca> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------8X4XvH4ckeU4gxW3O270aypK" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1638273205; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=eVy0aVIE1mERytOkkU1P79PIx36MoUgZiPIx9aKygd8=; b=MCOH5XkN2f56wvRiq7WaMpqxDHB3x/ZzOUZV5eEKF4TPX6qfzYoyI6fS/P7f7SMxJFX1Eb ULR6AKKHJ5Iiqn471WesMYBgrG3GscKM8ZphKLqywCRR/dScijro/4ISsCDdE0SKRhn2ii lIZsfbv7Xkq2avRLZJbjW9PbBXxLYLv5Ph3vfCJ+Qm9KFO+bKpy4epv0R4t6okwVDEHwfl skUxuHMhLnLNp71jtlfrqa07HIe2w9HUCDb72glP3QGi44Bhd13endjoJDFfKM7cGs1M6m l+aiXihO0iYQEHPRsaC9RZ3H6C4aAoYyAMHZ3r+I7hHozcd73PnoK0yfK75TVA== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1638273205; a=rsa-sha256; cv=none; b=xEft1qAg4bYw2i9EC7uA1UPHsi8xu5pQK0AlI2oy5eVufNUP6C2CIgSxhTlsVKnjbosvmA milHLcdLmDJJ7RthIbOw15q4wKN78+PbC5a1Qoyhz7I4fvWCBTggstZN4kJ1xcblNGq9Ep /errL8JWFvH4MOSQ24kyrcF+++ztDa6mjSOcr4GWA+pmWvi+f+AezGJIp7wnZ1eF78Un+5 +2f/SyL73sZjSwiHj9tkTcKTNpi891tVIKO0RYNb537niCMbAw689c32X2wR5JqggppgDb s3OK1ue5/HeFh82X7/9Xfsc6iK8znD+RTqYEp8uhv/XyWoei8v/KvmOY6MevOA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------8X4XvH4ckeU4gxW3O270aypK Content-Type: multipart/mixed; boundary="------------SB1EV19uYbJkmCPSY0AgS0xL"; protected-headers="v1" From: Stefan Esser To: Joseph Mingrone , FreeBSD Hackers Message-ID: Subject: Re: Call for Foundation-supported Project Ideas References: <861r36xzpe.fsf@phe.ftfl.ca> In-Reply-To: <861r36xzpe.fsf@phe.ftfl.ca> --------------SB1EV19uYbJkmCPSY0AgS0xL Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Am 23.11.21 um 23:41 schrieb Joseph Mingrone: > Hello FreeBSD community, >=20 > The Foundation is seeking suggestions for new projects to support. Wha= t > gaps in the Project are not being addressed by the broader community? The "new" ULE scheduler has a number of well-known issues, which leads to the "old" BSD scheduler giving better performance on many systems and loads, but is based on concepts that made sense in pre-SMP times. ULE suffers from pathological behavior in many scenarios, and it does not know how to best deal with simultaneous multi-threading, big/little architectures, or the effects of virtualization. ULE does not care for the "niceness" of a process and lets nice -19 processes run with hardly any reduction of the share of CPU cycles granted compared to competing nice 0 processes, for example. Virtualization gives a number of additional requirements and restrictions= in both the host and client. Schedulers in other operating systems have been modified to reduce the risk of side-channel attacks by running only processes for one user at a time on the virtual processors of an SMT core= =2E Within a virtual machine, the real topology of the underlying hardware may be hidden and scheduling effects by the VM host may need to be taken into consideration (e.g. clock variations and "time jumps"). There is a connection to bhyve, at least (perhaps also to other virtualization platforms) that has to be taken into account. Another aspect is optimization for performance vs. optimization for low power use, which both require a specific scheduling strategy on complex CPU topologies. IMHO, a scheduler design that is based on experiences gained by other projects and our knowledge of deficiencies of the currently available schedulers in FreeBSD under specific loads could be a huge win for the project. This would be a long-term project, and I do not see any developer currently working on designing or implementing a new scheduler. There have been minor changes to SCHED_ULE, recently, but I'd think that a completely new design will be required, based on knowledge gained in the last 1 or 2 decades and able to deal with architectural changes that have occurred in that time frame. Regards, STefan --------------SB1EV19uYbJkmCPSY0AgS0xL-- --------------8X4XvH4ckeU4gxW3O270aypK Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature" -----BEGIN PGP SIGNATURE----- wsB5BAABCAAjFiEEo3HqZZwL7MgrcVMTR+u171r99UQFAmGmELAFAwAAAAAACgkQR+u171r99UTs +wgAxxfH21oG1Z6P9YHXIvy2dg1IPWo9AvFmFq2NWF5wmqLkvymGSIcorsd0f0b5xNx1y7pWripl PmVRQgMobwNNNLLVWazOkAXEzHBPZJULwsCqLj0FvMwgQ5H6WSprs8I9C8WGwHUPMhhdEp4r+bYG X7IPHJZsfhS9KHdlX0+NvX4SD3C4jbz1fXaMYFb3rC1QoxSlnodmrnsAo7C+Oon4gGa/CLpTDhdj w9VxujPC/3SA/m80jl/z4MWVAu5RBorTv0j2Nskag524Zvr1YgznSCNwt0efgOnMyqo2my56PbMF PFBEiJqJEcAmjwf8gVdLknXqkEhDynB5sLHUPWUT7A== =fs4t -----END PGP SIGNATURE----- --------------8X4XvH4ckeU4gxW3O270aypK--