From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Thu, 26 Feb 2004 05:18:57 +0000 Subject: RE: HUGEPAGE SIZE a boottime option Message-Id: <16445.33217.472790.188648@napali.hpl.hp.com> List-Id: References: <20040220010731.GA28820@sgi.com> In-Reply-To: <20040220010731.GA28820@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Wed, 25 Feb 2004 17:26:25 -0800, "Chen, Kenneth W" said: Ken> We believe we have resolved all the remain issues, all critical Ken> speed path has been taken care of, i.e., vhpt hander and Ken> context switch. There should be no performance penalty with Ken> this dynamic hugetlb page size feature. What about huge-page page-faults? Before, HPAGE_SHIFT, HPAGE_SIZE, and HPAGE_MASK all were constant, now they have to be fetched from memory/recalculated each time. I suppose it's rare enough that it's not worth worrying about but did you verify that there is at least not anything really gross going on (like someone doing a modulo operation against HPAGE_SIZE)? How about replacing 0x8000000000000000 with (REGION_HPAGE << REGION_SHIFT) or a manifest constant defined to this value (perhaps HUGETLB_REGION_ADDR)? Why does the region register get initialized both in mm/init.c and hugetlb_setup_sz()? Couldn't this be done once in hugetlb_init()? Other than that, the patch looks good to me. --david