From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] xen: increase static dmesg buffer to 64K Date: Mon, 18 Jul 2011 09:33:22 +0100 Message-ID: References: <20110718081628.GA22448@aepfle.de> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110718081628.GA22448@aepfle.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Olaf Hering , Jan Beulich Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 18/07/2011 09:16, "Olaf Hering" wrote: > On Mon, Jul 18, Jan Beulich wrote: > >>>>> On 17.07.11 at 17:43, Olaf Hering wrote: >>> # HG changeset patch >>> # User Olaf Hering >>> # Date 1310917380 -7200 >>> # Node ID c6cade90d47f32e19f529930ba9f9acfa69f065f >>> # Parent 31dd84463eece20bd01c7aee22b52a0c06c67545 >>> xen: increase static dmesg buffer to 64K >>> >>> On large systems the static dmesg buffer will overflow the 16K buffer, early >>> messages are lost. Increase the size to 64K to capture all lines on systems >>> without serial console. >> >> Please don't - on small systems it's a waste, and on even larger >> systems it still won't help. If anything, the dynamic allocation may >> need to happen earlier. As you probably saw, console_init_postirq() >> already sizes the buffer dependent on the number of CPUs in the >> system. > > I think conring_size= should be evaluated very early. Is there a way to > allocate a range of mfns very early which can then be used for the dmesg > buffer? Are you actually losing messages because you can't allocate the larger console ring early enough? It seems a bit unlikely, but possible I suppose. Anyhow, the normal memory allocator is available plenty early enough. You'd just need to do the allocation earlier than console_init_postirq(). Sometime soon after the call to end_boot_allocator() would work nicely. -- Keir > Olaf > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel