From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from neon.transmeta.com (neon-best.transmeta.com [206.184.214.10]) by kvack.org (8.8.7/8.8.7) with ESMTP id NAA17072 for ; Wed, 26 May 1999 13:44:43 -0400 Date: Wed, 26 May 1999 10:44:02 -0700 (PDT) From: Linus Torvalds Subject: Re: [PATCH] cache large files in the page cache In-Reply-To: <19990526094407.J527@mff.cuni.cz> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Jakub Jelinek Cc: "Eric W. Biederman" , linux-kernel@vger.rutgers.edu, linux-mm@kvack.org List-ID: On Wed, 26 May 1999, Jakub Jelinek wrote: > > I have minor suggestion to the patch. Instead of using vm_index << > PAGE_SHIFT and page->key << PAGE_CACHE_SHIFT shifts either choose different > constant names for this shifting (VM_INDEX_SHIFT and PAGE_KEY_SHIFT) or hide > these shifts by some pretty macros (you'll need two for each for both > directions in that case - if you go the macro way, maybe it would be a good > idea to make vm_index and key type some structure with a single member like > mm_segment_t for more strict typechecking). Indeed. An dI would suggest that the shift be limited to at most 9 anyway: right now I applied the part that disallows non-page-aligned offsets, but I think that we may in the future allow anonymous mappings again at finer granularity (somebody made a really good argument about wine for this). Thinking that the VM mapping shift has to be the same as the page shift is not necessarily the right thing. With just 9 bits of shift, you still get large files - 41 bits of files on a 32-bit architecture, and by the time you want more you _really_ can say that you had better upgrade your CPU. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm my@address' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/