From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 7 Feb 2002 14:58:44 -0700 From: Val Henson To: "Mark A. Greer" Cc: Benjamin Herrenschmidt , linuxppc-dev@lists.linuxppc.org Subject: Re: Highmem on PPC? Message-ID: <20020207145844.F19569@boardwalk> References: <20020205115618.D6834@boardwalk> <20020205193316.19866@smtp.wanadoo.fr> <20020207144308.C19569@boardwalk> <3C62F74F.DE090C2C@mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <3C62F74F.DE090C2C@mvista.com>; from mgreer@mvista.com on Thu, Feb 07, 2002 at 02:53:19PM -0700 Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: On Thu, Feb 07, 2002 at 02:53:19PM -0700, Mark A. Greer wrote: > > Val Henson wrote: > > > Also, I don't think this was a particularly good test of highmem since > > I don't think many bounce buffers were used, or that the kernel had > > much reason to map/unmap many highmem pages. Unfortunately, my SCSI > > controller isn't working quite right and I can't test with a hard disk > > as a result. Any ideas for stressing the system harder? > > You could try lowering max_low_mem. You can do this by setting "Code > maturity level option"/"Prompt for advanced kernel configuration options" > and then going under where you selected HIGH_MEM and setting max_low_mem > size to something small. > > It will likely take some trial and error to get it stressed enough. > You'll have to start a bunch or processes and look at where they're > getting their memory See, I don't think that user processes using highmem pages is testing highmem much. So we have user pages mapped by PTE's - what's changed? Not a whole lot. It's when we use bounce buffers in the kernel or ask the kernel to map user pages or otherwise trigger the kmap/kunmap code that I'm interested in. -VAL ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/