From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Seth, Rohit" Date: Fri, 07 Sep 2001 17:01:08 +0000 Subject: RE: [Linux-ia64] IA64 Linux Kernel Page Sizes Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org I have an early prototype of super large page(256MB) implementation. This is only a proof of concept for large apps (and configurations) to use super large pages. The use is for apps that need large data regions (Instructions and regular data still use regular page size). Current implementation is through shared memory calls (shmat) with either SHM_LPAGE (a new flag) or size of requested segment >=LPAGE_SIZE(256MB). In either case the size has to be multiple of LPAGE_SIZE to get a large shared memory segment. Further the whole physical memory is divided in two parts, one that is seen by kernel and the other that is only used to fill in large page requests. And there is no moving of memory between two parts (in case of shortages). This implementation is based on 2.4.5 kernel. Currently IA-32 apps don't work in this environment, but that can be fixed. Let me know if this fits in your requirements and you want to give this a try. I can send you a cut of (modified)tar files out of my source tree early next week. rohit -----Original Message----- From: Donny Cooper [mailto:dcooper@atcc.necsys.com] Sent: Thursday, September 06, 2001 9:23 AM To: linux-ia64@linuxia64.org Cc: Cooper (E-mail) Subject: [Linux-ia64] IA64 Linux Kernel Page Sizes (1) Below is a previous mail, from David M., responding to page size questions for IA64 kernels. > As for the future: I'd like to start playing with superpage support > fairly soon (once I get some spare time on my hands... ;-). With > superpages, physically contiguous regions of memory could be mapped > with a single TLB entry, giving you most of the benefit of (very) > large page sizes. --david Are there any updates on these plans? (2) Below are current available kernel options (from config). 4KB For best IA-32 compatibility 8KB For best IA-64 performance 16KB For best IA-64 performance 64KB Not for Itanium. What is "IA64 best performance" based on? We have a large memory system (32GB), and are not concerned with wasting memory during certain benchmarks. Are 64KB pages truly not functional on Itanium, or just not recommended because of memory waste. To my knowledge, HP-UX seems to benefit from 64KB pages on ITANIUM. Any input or recommendation on these items is appreciated. Thanks. ----------------------------------- Donny Cooper NEC Systems, Inc. Advanced Technical Computing Center dcooper@atcc.necsys.com www.necservers.com ----------------------------------- _______________________________________________ Linux-IA64 mailing list Linux-IA64@linuxia64.org http://lists.linuxia64.org/lists/listinfo/linux-ia64