From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sun, 16 Oct 2005 12:59:53 +0100 (IST) From: Mel Gorman Subject: Re: [PATCH 0/8] Fragmentation Avoidance V17 In-Reply-To: <20051015195213.44e0dabb.pj@sgi.com> Message-ID: References: <20051011151221.16178.67130.sendpatchset@skynet.csn.ul.ie> <20051015195213.44e0dabb.pj@sgi.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Paul Jackson Cc: akpm@osdl.org, jschopp@austin.ibm.com, kravetz@us.ibm.com, Linux Kernel Mailing List , Linux Memory Management List , lhms-devel@lists.sourceforge.net List-ID: On Sat, 15 Oct 2005, Paul Jackson wrote: > Mel wrote: > > +#define __GFP_USER 0x80000u /* User and other easily reclaimed pages */ > > +#define __GFP_KERNRCLM 0x100000u /* Kernel page that is reclaimable */ > > Sorry, but that __GFP_USER name is still sticking in my craw. > > I won't try to reopen my quest to get it named __GFP_REALLY_REALLY_EASY_RCLM > or whatever it was, but instead will venture on a new quest. > > Can we get the 'RCLM' in there. Especially since this term appears > naked in such code as: > __GFP_USERRCLM is the original name and the motivation for changing it to __GFP_USER no longer exists. However, __GFP_EASYRCLM would also make sense as it flags pages that are (surprise surprise) easily reclaimed. Would __GFP_EASYRCLM be the best choice? __GFP_USERRCLM may imply to some readers that it is reclaimed by the user somehow. The flags would then be; __GFP_EASYRCLM - Allocations for pages that are easily reclaimed such as userspace and buffer pages __GFP_KERNRCLM - Allocations for pages that may be reclaimed by the kernel such as caches No flag - Page cannot be easily reclaimed by any mechanism. I would be happy with __GFP_USERRCLM but __GFP_EASYRCLM may be more obvious? > > - page = alloc_page(GFP_HIGHUSER); > > + page = alloc_page(GFP_HIGHUSER|__GFP_USER); > > where it is not at all obvious to the reader of this file (fs/exec.c) > that the __GFP_USER term is commenting on the reclaim behaviour of > the page to be allocated. > > I'd be happier with: > > > +#define __GFP_USERRCLM 0x80000u /* User and other easily reclaimed pages */ > > +#define __GFP_KERNRCLM 0x100000u /* Kernel page that is reclaimable */ > > and: > > > - page = alloc_page(GFP_HIGHUSER); > > + page = alloc_page(GFP_HIGHUSER|__GFP_USERRCLM); > > Also the bold assymetry of these two #defines seems to be without motivation, > one with the 'RCLM', and the other with ' ' four spaces. > > -- Mel Gorman Part-time Phd Student Java Applications Developer University of Limerick IBM Dublin Software Lab -- 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/ . Don't email: email@kvack.org