From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 9 Jul 2001 15:18:43 +0100 (BST) From: Hugh Dickins Subject: Re: [wip-PATCH] Re: Large PAGE_SIZE In-Reply-To: <3B49AE09.CE19FBAC@mandrakesoft.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Jeff Garzik Cc: Ben LaHaise , Linus Torvalds , linux-mm@kvack.org List-ID: On Mon, 9 Jul 2001, Jeff Garzik wrote: > Hugh Dickins wrote: > > On Sun, 8 Jul 2001, Ben LaHaise wrote: > > > > > > Hmmm, interesting. At present page cache sizes from PAGE_SIZE to > > > 8*PAGE_SIZE are working here. Setting the shift to 4 or a 64KB page size > > > results in the SCSI driver blowing up on io completion. > > > > I hit that limit too: I believe it comes from unsigned short b_size. > > That limit's not a big deal.. the limits in the lower-level disk drivers > are what you start hitting... Examples? Limits below 64kB with some drivers we happen not to be using, or limits >= 64kB we'd soon hit if we chose to do something about unsigned short b_size (e.g. short sizes in the drivers own code)? Limits in the disk drivers or limits in their firmware? If the limits are in the drivers, then they're probably PAGE_SIZE limits which raising PAGE_SIZE deals with automatically, but raising PAGE_CACHE_SIZE needs more edits to get working. (Whereas raising PAGE_SIZE needs edits where it's the vm_pgoff MMAP_? MMU_? PTE_? VM_? SUB? PAGE_SIZE that's needed.) Linus believes it would be no more than a few buggy drivers which would impose such limits; I don't know, I took little notice of the instances I didn't need to change in raising PAGE_SIZE. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/