From mboxrd@z Thu Jan 1 00:00:00 1970 From: "William J. Earl" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14416.15954.354222.915088@liveoak.engr.sgi.com> Date: Thu, 9 Dec 1999 15:42:10 -0800 (PST) Subject: Re: Getting big areas of memory, in 2.3.x? In-Reply-To: References: <14416.10643.915336.498552@liveoak.engr.sgi.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Alan Cox Cc: mingo@chiara.csoma.elte.hu, jgarzik@mandrakesoft.com, linux-kernel@vger.rutgers.edu, linux-mm@kvack.org List-ID: Alan Cox writes: > > That is not the case for loadable (modular) drivers. Loading st > > as a module, for example, after boot time sometimes works and sometimes does > > not, especially if you set the maximum buffer size larger (to, say, 128K, > > as is needed on some drives for good space efficiency). > > Dont mix up crap code with crap hardware. Scsi generic had similar problems > and has been fixed. There are very very few non scatter-gather scsi controllers I only mentioned st as example of the inability to get a large page long after system startup. Large pages are good for a variety of purposes. For example, large pages for programs with large code or data footprints can dramatically reduce TLB misses. If the I/O system learns to do direct I/O, the overhead of setting up large I/O operations, whether for disk I/O or for OpenGL operations such as writing a large image to the screen (via DMA), is much reduced when the I/O is done from large pages. The CPU overhead of setting up I/O operations is pretty minimal when you are doing file I/O to and from a single IDE disk, but far from minimal for higher-bandwidth targets, such as a graphics controller or a HDTV camera. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/