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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0EB38EA794F for ; Thu, 5 Feb 2026 01:36:32 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.1221354.1529648 (Exim 4.92) (envelope-from ) id 1vnoI9-0002d4-0b; Thu, 05 Feb 2026 01:36:21 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1221354.1529648; Thu, 05 Feb 2026 01:36:20 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1vnoI8-0002ct-Sj; Thu, 05 Feb 2026 01:36:20 +0000 Received: by outflank-mailman (input) for mailman id 1221354; Thu, 05 Feb 2026 01:36:19 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1vnoI6-0002Qc-Ul for xen-devel@lists.xenproject.org; Thu, 05 Feb 2026 01:36:18 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.96) (envelope-from ) id 1vnoI6-003wQh-01; Thu, 05 Feb 2026 01:36:17 +0000 Received: from [140.209.201.102] (helo=localhost) by xenbits.xenproject.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1vnoI5-00HVXL-1b; Thu, 05 Feb 2026 01:36:17 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-ID:Date:Subject:Cc:To:From; bh=uMEQbYnd5xAAaBu981UD1vQcoXX8eKP0LOT3hk6YJ3Q=; b=mam4JDzfk/p6OWqgGA5SomxTJ1 kfYr2LSIJttLdq4REByJY0418pIva21EdHEZQIO78b3QA0GPewW29bZ0QHloo0DXgouG4vk2mrXcv mviqLNow7s48GtjqYemVl4uDFo1wfUx6XF4hlmHTfx54LHwxzj9LP/4Aocal7ROGpHfk=; From: dmukhin@xen.org To: xen-devel@lists.xenproject.org Cc: andrew.cooper3@citrix.com, anthony.perard@vates.tech, jbeulich@suse.com, julien@xen.org, michal.orzel@amd.com, roger.pau@citrix.com, sstabellini@kernel.org, dmukhin@ford.com Subject: [PATCH v5 4/6] xen/console: use memcpy() in console_init_ring() Date: Wed, 4 Feb 2026 17:36:04 -0800 Message-ID: <20260205013606.3384798-5-dmukhin@ford.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260205013606.3384798-1-dmukhin@ford.com> References: <20260205013606.3384798-1-dmukhin@ford.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Denis Mukhin Make console_init_ring() more efficient by using memcpy()'s, rather than copying the ring a byte at a time. Suggested-by: Andrew Cooper Signed-off-by: Denis Mukhin --- Changes since v4: - new patch --- xen/drivers/char/console.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c index ef9131439bba..3ad86fd436e2 100644 --- a/xen/drivers/char/console.c +++ b/xen/drivers/char/console.c @@ -463,7 +463,7 @@ static void cf_check conring_dump_keyhandler(unsigned char key) void __init console_init_ring(void) { char *ring; - unsigned int i, order, memflags; + unsigned int start, size, chunk, order, memflags; unsigned long flags; if ( !opt_conring_size ) @@ -479,11 +479,23 @@ void __init console_init_ring(void) opt_conring_size = PAGE_SIZE << order; nrspin_lock_irqsave(&console_lock, flags); - for ( i = conringc ; i != conringp; i++ ) - ring[i & (opt_conring_size - 1)] = conring[i & (conring_size - 1)]; + + start = conringc & (conring_size - 1); + size = min(conringp - conringc, conring_size); + chunk = min(size, conring_size - start); + + memcpy(&ring[0], &conring[start], chunk); + if ( size > chunk ) + memcpy(&ring[chunk], &conring[0], size - chunk); + + /* Data is moved to [0..size), re-position conring pointers. */ + conringc = 0; + conringp = size; + conring = ring; smp_wmb(); /* Allow users of console_force_unlock() to see larger buffer. */ conring_size = opt_conring_size; + nrspin_unlock_irqrestore(&console_lock, flags); printk("Allocated console ring of %u KiB.\n", opt_conring_size >> 10); -- 2.52.0