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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44DC0C432C0 for ; Tue, 19 Nov 2019 12:18:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22B832230F for ; Tue, 19 Nov 2019 12:18:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727859AbfKSMSI (ORCPT ); Tue, 19 Nov 2019 07:18:08 -0500 Received: from mga05.intel.com ([192.55.52.43]:64330 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725280AbfKSMSI (ORCPT ); Tue, 19 Nov 2019 07:18:08 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2019 04:18:08 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,322,1569308400"; d="scan'208";a="209179842" Received: from unknown (HELO [10.239.13.7]) ([10.239.13.7]) by orsmga003.jf.intel.com with ESMTP; 19 Nov 2019 04:18:06 -0800 Message-ID: <5DD3DF17.9050504@intel.com> Date: Tue, 19 Nov 2019 20:24:55 +0800 From: Wei Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org CC: Khazhismel Kumykov , Jason Wang , virtualization@lists.linux-foundation.org Subject: Re: [PATCH 2/2] virtio_balloon: divide/multiply instead of shifts References: <20191119102838.39380-1-mst@redhat.com> <20191119102838.39380-2-mst@redhat.com> In-Reply-To: <20191119102838.39380-2-mst@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/19/2019 06:29 PM, Michael S. Tsirkin wrote: > We managed to get confused about the shift direction at least once. > Let's switch to division/multiplcation instead. Add a number of pages > macro for this purpose. We still keep the order macro around too since > this is what alloc/free pages want. > > Signed-off-by: Michael S. Tsirkin > --- > drivers/virtio/virtio_balloon.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index b6a95cd28d9f..dc1ebd638e9b 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -36,6 +36,7 @@ > /* The size of a free page block in bytes */ > #define VIRTIO_BALLOON_HINT_BLOCK_BYTES \ > (1 << (VIRTIO_BALLOON_HINT_BLOCK_ORDER + PAGE_SHIFT)) > +#define VIRTIO_BALLOON_HINT_BLOCK_PAGES (1 << VIRTIO_BALLOON_HINT_BLOCK_ORDER) > > #ifdef CONFIG_BALLOON_COMPACTION > static struct vfsmount *balloon_mnt; > @@ -765,11 +766,11 @@ static unsigned long shrink_free_pages(struct virtio_balloon *vb, > unsigned long blocks_to_free, blocks_freed; > > pages_to_free = round_up(pages_to_free, > - 1 << VIRTIO_BALLOON_HINT_BLOCK_ORDER); > - blocks_to_free = pages_to_free >> VIRTIO_BALLOON_HINT_BLOCK_ORDER; > + VIRTIO_BALLOON_HINT_BLOCK_PAGES); > + blocks_to_free = pages_to_free / VIRTIO_BALLOON_HINT_BLOCK_PAGES; > blocks_freed = return_free_pages_to_mm(vb, blocks_to_free); > > - return blocks_freed << VIRTIO_BALLOON_HINT_BLOCK_ORDER; > + return blocks_freed * VIRTIO_BALLOON_HINT_BLOCK_PAGES; > } > > static unsigned long leak_balloon_pages(struct virtio_balloon *vb, > @@ -825,7 +826,7 @@ static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, > unsigned long count; > > count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE; > - count += vb->num_free_page_blocks << VIRTIO_BALLOON_HINT_BLOCK_ORDER; > + count += vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES; > > return count; > } Reviewed-by: Wei Wang Best, Wei