From patchwork Tue Feb 9 02:12:23 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 8257791 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 3058FBEEE5 for ; Tue, 9 Feb 2016 02:11:57 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 88F782022A for ; Tue, 9 Feb 2016 02:11:56 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CD2722021F for ; Tue, 9 Feb 2016 02:11:55 +0000 (UTC) Received: from localhost ([::1]:50858 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aSxmV-0007C0-52 for patchwork-qemu-devel@patchwork.kernel.org; Mon, 08 Feb 2016 21:11:55 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48736) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aSxmB-0006wj-Ta for qemu-devel@nongnu.org; Mon, 08 Feb 2016 21:11:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aSxm7-0000hH-RU for qemu-devel@nongnu.org; Mon, 08 Feb 2016 21:11:35 -0500 Received: from ozlabs.org ([103.22.144.67]:52519) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aSxm7-0000gs-GU; Mon, 08 Feb 2016 21:11:31 -0500 Received: by ozlabs.org (Postfix, from userid 1007) id E5B791409B7; Tue, 9 Feb 2016 13:11:26 +1100 (AEDT) From: David Gibson To: benh@kernel.crashing.org, aik@ozlabs.ru, agraf@suse.de Date: Tue, 9 Feb 2016 12:12:23 +1000 Message-Id: <1454983946-32073-5-git-send-email-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1454983946-32073-1-git-send-email-david@gibson.dropbear.id.au> References: <1454983946-32073-1-git-send-email-david@gibson.dropbear.id.au> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 103.22.144.67 Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, David Gibson Subject: [Qemu-devel] [PATCHv2 4/7] pseries: Add helper to calculate recommended hash page table size X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP At present we calculate the recommended hash page table (HPT) size for a pseries guest just once in ppc_spapr_init() before allocating the HPT. In future patches we're going to want this calculation in other places, so this splits it out into a helper function. While we're at it, change the calculation to use ctz() instead of an explicit loop. Signed-off-by: David Gibson --- hw/ppc/spapr.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index c315715..2a81e8f 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -1050,6 +1050,19 @@ static void close_htab_fd(sPAPRMachineState *spapr) spapr->htab_fd = -1; } +static int spapr_hpt_shift_for_ramsize(uint64_t ramsize) +{ + int shift; + + /* We aim for a hash table of size 1/128 the size of RAM (rounded + * up). The PAPR recommendation is actually 1/64 of RAM size, but + * that's much more than is needed for Linux guests */ + shift = ctz64(pow2ceil(ramsize)) - 7; + shift = MAX(shift, 18); /* Minimum architected size */ + shift = MIN(shift, 46); /* Maximum architected size */ + return shift; +} + static void spapr_alloc_htab(sPAPRMachineState *spapr) { long shift; @@ -1790,16 +1803,7 @@ static void ppc_spapr_init(MachineState *machine) /* Setup a load limit for the ramdisk leaving room for SLOF and FDT */ load_limit = MIN(spapr->rma_size, RTAS_MAX_ADDR) - FW_OVERHEAD; - /* We aim for a hash table of size 1/128 the size of RAM. The - * normal rule of thumb is 1/64 the size of RAM, but that's much - * more than needed for the Linux guests we support. */ - spapr->htab_shift = 18; /* Minimum architected size */ - while (spapr->htab_shift <= 46) { - if ((1ULL << (spapr->htab_shift + 7)) >= machine->maxram_size) { - break; - } - spapr->htab_shift++; - } + spapr->htab_shift = spapr_hpt_shift_for_ramsize(machine->maxram_size); spapr_alloc_htab(spapr); /* Set up Interrupt Controller before we create the VCPUs */