From patchwork Mon Jan 7 15:38:48 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 210011 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 110162C00A6 for ; Tue, 8 Jan 2013 04:10:01 +1100 (EST) Received: from localhost ([::1]:58495 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TsGD1-0000xi-2J for incoming@patchwork.ozlabs.org; Mon, 07 Jan 2013 12:09:59 -0500 Received: from eggs.gnu.org ([208.118.235.92]:41255) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TsEnR-0005D2-Lx for qemu-devel@nongnu.org; Mon, 07 Jan 2013 10:39:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TsEnJ-0007CR-Jw for qemu-devel@nongnu.org; Mon, 07 Jan 2013 10:39:29 -0500 Received: from cantor2.suse.de ([195.135.220.15]:39908 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TsEnJ-0007C8-BC; Mon, 07 Jan 2013 10:39:21 -0500 Received: from relay1.suse.de (unknown [195.135.220.254]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id C2D53A51D9; Mon, 7 Jan 2013 16:39:17 +0100 (CET) From: Alexander Graf To: qemu-devel@nongnu.org Date: Mon, 7 Jan 2013 16:38:48 +0100 Message-Id: <1357573140-8877-20-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.6.0.2 In-Reply-To: <1357573140-8877-1-git-send-email-agraf@suse.de> References: <1357573140-8877-1-git-send-email-agraf@suse.de> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x X-Received-From: 195.135.220.15 Cc: Blue Swirl , Scott Wood , qemu-ppc@nongnu.org, Aurelien Jarno Subject: [Qemu-devel] [PATCH 19/31] Revert "openpic: Accelerate pending irq search" 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Scott Wood This reverts commit a9bd83f4c65de0058659ede009fa1a241f379edd. This counting approach is not robust against setting a bit that was already set, or clearing a bit that was already clear. Perhaps that is considered a bug, but besides the lack of any documentation for that restriction, it's a pretty unpleasant way for the problem to manifest itself. It could be made more robust by testing the current value of the bit before changing the count, but a later patch speeds up IRQ_check in all cases, not just when there's nothing pending. Hopefully that should be adequate to address performance concerns. Signed-off-by: Scott Wood Signed-off-by: Alexander Graf --- hw/openpic.c | 11 ----------- 1 files changed, 0 insertions(+), 11 deletions(-) diff --git a/hw/openpic.c b/hw/openpic.c index 19e6280..2c238fb 100644 --- a/hw/openpic.c +++ b/hw/openpic.c @@ -183,7 +183,6 @@ typedef struct IRQQueue { uint32_t queue[BF_WIDTH(MAX_IRQ)]; int next; int priority; - int pending; /* nr of pending bits in queue */ } IRQQueue; typedef struct IRQSource { @@ -269,13 +268,11 @@ typedef struct OpenPICState { static inline void IRQ_setbit(IRQQueue *q, int n_IRQ) { - q->pending++; set_bit(q->queue, n_IRQ); } static inline void IRQ_resetbit(IRQQueue *q, int n_IRQ) { - q->pending--; reset_bit(q->queue, n_IRQ); } @@ -291,12 +288,6 @@ static void IRQ_check(OpenPICState *opp, IRQQueue *q) next = -1; priority = -1; - - if (!q->pending) { - /* IRQ bitmap is empty */ - goto out; - } - for (i = 0; i < opp->max_irq; i++) { if (IRQ_testbit(q, i)) { DPRINTF("IRQ_check: irq %d set ivpr_pr=%d pr=%d\n", @@ -307,8 +298,6 @@ static void IRQ_check(OpenPICState *opp, IRQQueue *q) } } } - -out: q->next = next; q->priority = priority; }