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 82905C4332F for ; Tue, 16 Nov 2021 15:41:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 700F061502 for ; Tue, 16 Nov 2021 15:41:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238410AbhKPPos (ORCPT ); Tue, 16 Nov 2021 10:44:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:50948 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238631AbhKPPnw (ORCPT ); Tue, 16 Nov 2021 10:43:52 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D1BF160F38; Tue, 16 Nov 2021 15:40:53 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mn0Zn-005s77-F7; Tue, 16 Nov 2021 15:40:51 +0000 Date: Tue, 16 Nov 2021 15:40:50 +0000 Message-ID: <877dd885x9.wl-maz@kernel.org> From: Marc Zyngier To: Paolo Bonzini Cc: kvm@vger.kernel.org, linux-mips@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linuxppc-dev@lists.ozlabs.org, Huacai Chen , Aleksandar Markovic , Anup Patel , Atish Patra , Christian Borntraeger , Janosch Frank , David Hildenbrand , Claudio Imbrenda , Juergen Gross , Nicholas Piggin , Sean Christopherson , Paul Mackerras , Michael Ellerman , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: Re: [PATCH 0/5] KVM: Turn the vcpu array into an xarray In-Reply-To: References: <20211105192101.3862492-1-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: pbonzini@redhat.com, kvm@vger.kernel.org, linux-mips@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linuxppc-dev@lists.ozlabs.org, chenhuacai@kernel.org, aleksandar.qemu.devel@gmail.com, anup.patel@wdc.com, atish.patra@wdc.com, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, jgross@suse.com, npiggin@gmail.com, seanjc@google.com, paulus@samba.org, mpe@ellerman.id.au, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Tue, 16 Nov 2021 15:03:40 +0000, Paolo Bonzini wrote: > > On 11/5/21 20:20, Marc Zyngier wrote: > > The kvm structure is pretty large. A large portion of it is the vcpu > > array, which is 4kB on x86_64 and arm64 as they deal with 512 vcpu > > VMs. Of course, hardly anyone runs VMs this big, so this is often a > > net waste of memory and cache locality. > > > > A possible approach is to turn the fixed-size array into an xarray, > > which results in a net code deletion after a bit of cleanup. > > > > This series is on top of the current linux/master as it touches the > > RISC-V implementation. Only tested on arm64. > > Queued, only locally until I get a review for my replacement of patch > 4 (see > https://lore.kernel.org/kvm/20211116142205.719375-1-pbonzini@redhat.com/T/). In which case, let me send a v2 with the changes that we discussed with Sean. It will still have my version of patch 4, but that's nothing you can't fix. M. -- Without deviation from the norm, progress is not possible.