From mboxrd@z Thu Jan 1 00:00:00 1970 From: Erich Focht Date: Mon, 10 Sep 2001 20:31:46 +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 Dear Rohit, I'd like to try the super large pages which you mentioned in your mail. I tried the 64k pages with IA64 Linux but the performance advantage was less than expected (at least with the applications I used)... Thanks a lot in advance! Best regards, Erich --- Erich Focht NEC European Supercomputer Systems, European HPC Technology Center On Fri, 7 Sep 2001, Seth, Rohit wrote: > 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 > -----------------------------------