From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 15 May 2000 16:27:38 -0300 (BRST) From: Rik van Riel Subject: Re: [patch] VM stable again? In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Molnar Cc: "Stephen C. Tweedie" , Linus Torvalds , linux-mm@kvack.org List-ID: On Mon, 15 May 2000, Ingo Molnar wrote: > On Mon, 15 May 2000, Rik van Riel wrote: > > > I've thought about this but it doesn't seem worth the extra complexity > > to me. Just making sure that while our task is freeing pages nobody > > else will grab those pages without having also freed some pages seems > > to be enough to me. > > actually wouldnt it be simpler to always call > try_to_free_pages() when the zone is low on memory? This will > keep the pressure on the system to recover from the low memory > situation, and it reuses the low_on_memory flag. The new > free_before_allocate flag is a 'now we are really low on memory' > flag. This would disturb the balancing between zones. We do not want to have this flag per-zone since it would return us to the "16/64MB unused" problem (and I believe you've seen it too with highmem). > > Furthermore, the "SMP locality" you talk about will probably be > > completely overshadowed by the non-locality of the VM freeing code > > anyway... > > But it would be a performance optimization for sure, a > __free_pages() + __alloc_pages() is saved - this can make a big > difference if (a mostly clean) pagecache is shrunk. But we shrink 'count' pages at the same time. It would only save 2 operations out of a *lot*. A much bigger win could be had if the list operations in shrink_mmap() would be made simpler or lower overhead... regards, Rik -- The Internet is not a network of computers. It is a network of people. That is its real strength. Wanna talk about the kernel? irc.openprojects.net / #kernelnewbies http://www.conectiva.com/ http://www.surriel.com/ -- 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.eu.org/Linux-MM/