From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fl1YxtP0" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90385136 for ; Tue, 21 Nov 2023 04:26:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700569615; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ae4ycoDofu+C26tPS9A9NfrBD29puf5F6yHlPPACb1Y=; b=fl1YxtP0nwcXtUhnyEPLfP37Rixwd257FZNvDUKpT0Dcs+dmQVsWR9qu62Ad3q34LW+WQr Trt3292Y8AaPTkpQZ8nTCyGBF81DQMR/rVEO0sIeTIpbhgUJG0sNbGFVNaM/U7lyo+e3S/ tNuEdeVokC3VNCDtlCHhXtFVEXqfO68= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-686-1jJhdz0jNDmQnmM1D_I5_w-1; Tue, 21 Nov 2023 07:26:52 -0500 X-MC-Unique: 1jJhdz0jNDmQnmM1D_I5_w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2FEDC3C0F68C; Tue, 21 Nov 2023 12:26:52 +0000 (UTC) Received: from fedora (unknown [10.72.120.14]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D5ED31C060AE; Tue, 21 Nov 2023 12:26:48 +0000 (UTC) Date: Tue, 21 Nov 2023 20:26:44 +0800 From: Ming Lei To: Yu Kuai Cc: Jens Axboe , linux-block@vger.kernel.org, Jan Kara , "yukuai (C)" Subject: Re: [PATCH] block: move .bd_inode into 1st cacheline of block_device Message-ID: References: <20231121101156.378105-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 On Tue, Nov 21, 2023 at 07:36:34PM +0800, Yu Kuai wrote: > Hi, > > 在 2023/11/21 19:21, Ming Lei 写道: > > On Tue, Nov 21, 2023 at 07:12:44PM +0800, Yu Kuai wrote: > > > Hi, > > > > > > 在 2023/11/21 18:11, Ming Lei 写道: > > > > The .bd_inode field of block_device is used in IO fast path of > > > > blkdev_write_iter() and blkdev_llseek(), so it is more efficient to keep > > > > it into the 1st cacheline. > > > > > > > > .bd_openers is only touched in open()/close(), and .bd_size_lock is only > > > > for updating bdev capacity, which is in slow path too. > > > > > > > > So swap .bd_inode layout with .bd_openers & .bd_size_lock to move > > > > .bd_inode into the 1st cache line. > > > > > > This patch looks good, do you want me do take it for a v3 for the > > > other patchset? > > > > Yeah, please take it. > > Ok > > > > > > > > And by the way, can we also move 'int bd_writers' to near 'atomic_t > > > bd_fsfreeze_count' to save 8 bytes(int 64bit platform)? > > > > > > diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h > > > index 07abd0165226..a47ab9249bdd 100644 > > > --- a/include/linux/blk_types.h > > > +++ b/include/linux/blk_types.h > > > @@ -63,11 +63,11 @@ struct block_device { > > > int bd_holders; > > > struct kobject *bd_holder_dir; > > > > > > + int bd_writers; > > > atomic_t bd_fsfreeze_count; /* number of freeze > > > requests */ > > > struct mutex bd_fsfreeze_mutex; /* serialize freeze/thaw > > > */ > > > > > > struct partition_meta_info *bd_meta_info; > > > - int bd_writers; > > > > Which tree are you talking about? I don't see 'bd_writers' in both > > linus tree and block-6.7, and for-6.8/block isn't open yet. > > This is introduced from commit dc85fbc92365 ("block: Add config option > to not allow writing to mounted devices") from linux-next by Jan. Patch isn't supposed to be against linux-next, and either you need to base the change against maintainer tree(fs) or block tree when Jan's change lands linus tree. Thanks, Ming